ZMFheadphones Caldera

Introduction​

Hi Guys,

Today we are talking about the current Flagship headphones from ZMF, the Caldera. This is ZMF’s first entirely in-house designed and built planar magnetic headphone, and although ZMF has become mostly known for their high impedance dynamic driver headphones, the company’s roots are in providing modifications of Fostex T50 planar magnetics. Sadly, I’ve never actually heard any of ZMF’s older T50 modifications, but they had a bit of a cult following and there are still many people using them out there to this very day. Thankfully I do have some experience with other ZMF headphones, which I reviewed a few years ago on this blog. Those two headphones were the Eikon, a bio-cellulose closed-back dynamic driver headphone, and the Verite, an open-back beryllium-coated dynamic driver headphone. I really enjoyed both of those headphones, so I was very curious how things had evolved in the time period since those reviews, and also very curious what Zach (owner of ZMF headphones) had come up with in terms of his first proprietary planar magnetic driver-based headphones.

Aged Oak with Coffee Gold Hardware (from ZMF website)


In terms of looks, the Caldera is incredibly similar to other ZMF headphones. Artisan wooden earcups being the main visual feature, of many different types. The pair of Caldera that I have here for review is the current stock option, natural oak wood with black hardware. This currently retails for $3500USD, but there is another stock option at a $200USD upcharge which comes with an aged oak finish and coffee gold hardware. In the time elapsed since the last two reviews of ZMF headphones on this blog, Zach and the team at ZMF have massively increased the number of cosmetic options available. These come in the form of the usual limited edition wood runs, but also stabilized wood runs and stabilized/resin combo runs. These headphones vary massively in terms of colours and figuring of the wood, and also have various hardware colour combos, resulting in some truly spectacular-looking builds. I would never be able to fully feature all the different looks of these runs, so I will provide a link instead to ZMF’s YouTube. To be clear, this is not an affiliate link or sponsored in any way shape, or form, its just the easiest way to share some of the many looks now available from ZMF ()

The Caldera follows suit with the rest of the ZMF headphones lineup in that there are many different options in terms of pads to help tailor the sound to your personal preferences. There will always be traits that the headphones have across all pad options, but they certainly do vary widely, depending on the pads you choose. For the rest of this review, I will be speaking about the Caldera with the stock leather pads installed. I will then cover the individual pads and their specific sound traits in a separate section later in the review.

Sonic Impressions​

The bass of the caldera in terms of level is pretty much entirely flat, which is fairly characteristic of most planar magnetic headphones these days. That means that whilst they are definitely not bass light, or rolled off in the low end, if you prefer a more robust bass response (as I do) you can play about with boosting the low end via EQ. However, there are many people who I think will enjoy the bass in its stock tuning, and the tonal balance can also be tweaked with different pads as mentioned before. In terms of low-end impact, the Caldera was very similar to the LCD-5 I also had during the time of this review. This aspect did change quite drastically with the different pad options, but with the stock pads, the Caldera is not far behind the Abyss 1266TC, and again very similar to the LCD-5, providing a real amount of heft to kick drums, bass strikes, etc. In terms of speed and deftness of the bass response, the Caldera is right in the middle of the pack when it comes to top-of-the-line planar magnetic headphones. It isn’t fast, and it isn’t slow, it plays it straight down the middle. Overall, I was very happy with the low end of the Caldera, it is a standout in some areas, can be tweaked with the different pad choices, and increased easily via EQ to your preference if need be.

The mid-range of the Caldera was a change of pace from what I was expecting, and does show how ZMF doesn’t necessarily have a specific “house sound” these days, but individual headphones which all have their own characteristics and special qualities. I think in the past I have incorrectly associated ZMF with a slightly thicker warmer presentation, but that is not the case with the Caldera. Of course, this is with the stock pads and as I mentioned things can change with the pad choices, but with the stock pads, I would describe the lower mids as pretty much neutral, and the upper mids as being quite forward, in part. There isn’t any warm, gooey thickness in the low mid-range. They aren’t scooped out, or cold, leading to a v-shaped signature, but they definitely don’t come across as being boosted in any way. In the recent Audeze LCD-5 review I did, I spoke of the 3khz peak, and how it was problematic for me. With the Caldera, it is actually around about the 2khz range that there is a peak to my ears, and that 3khz is actually pulled back. I really like this take on upper-mid tuning. That increase in the 2khz region helps with things like rim shots on snare drums, stabs of synthesizers, and crashes of cymbals. When it is combined with that 3khz peak being pulled back, for me and my personal preferences, it sort of gives you the best of both worlds. The impact, and forwardness that helps keep things exciting, with just enough of the area that can make things harsh and grating reduced. Overall, the mid-range of the Caldera is one of my favourites out of all headphones in its stock tuning. There are no areas that annoy me or peaks that are too harsh, and the low mids aren’t too pulled back and sucked out, or overly increased and warm, losing perceived detail and technical performance.

The treble of the Caldera, using the stock pads, is very, very, slightly north of neutral. For me personally, I do prefer a tiny bit more high-end presence, but I could very happily listen to the Calderas treble in its stock form with no issues whatsoever. Compared to the LCD-5 which I felt really lacked treble energy and level, the Caldera is much more in line with my personal preferences. Having the treble slightly increased over being neutral helps keep things lively and also helps with perceived detail levels and technical performance, whilst not being overly boosted also helps provide a frequency response that isn’t bright, grating, and difficult to enjoy for long periods. Of course, as mentioned previously this can be tweaked with the various pad choices, but with the stock pads, it is just very slightly increased over what I would call a neutral treble response. The speed of the treble is very similar to the speed of the low end, in that it pretty much finds itself right in the middle of the pack compared to other flagship planar magnetic headphones. It isn’t fast and zippy like the Susvara, but it is quicker and has a better transient response than the Meze Elite’s.

Technical Performance​

The overall technical performance of the Caldera is very solid, and I do think it is the best of the ZMF headphones that I have been fortunate enough to hear. The Caldera seems to excel at the “macro” side of things more than the “micro” side of things (in terms of detail,) but isn’t a slouch at either. In terms of micro detail, the Hifiman HE1000se which was originally also priced at $3500USD, does provide more information and low-level detail, but in terms of the larger details, I would say that they are fairly close to each other. The soundstage of the Caldera is fairly mid-sized (with the stock pads), but where it excels is depth and 3D holography within that mid-sized soundstage. This depth and holographic nature is most noticeable with the stock pads, though the other pad options bring other qualities whilst lessening that aforementioned one. The Caldera isn’t the fastest or most detailed driver out of the current TOTL planar magnetic headphones (which also cost significantly more money, which cannot be understated,) but it has a quality that I don’t find in those other faster more detailed drivers. It is hard to describe but there is a “meat on the bones” and toothsome nature to the Caldera, entirely unrelated to frequency response, that I find incredibly compelling. They are just fun to listen to, and sometimes that is worth more than any detail or driver speed ever could be. With all of that being said, I have to make myself clear here, the Caldera is not a slouch of any sort when it comes to technical performance (detail, speed, etc..) it is incredibly competent, the best from ZMF that I have heard, and only slightly trailing behind headphones like the LCD-5 in these areas. I suppose I am trying to convey that the Caldera has other traits that I feel also fall under this area of the review which are harder to quantify, but very important to the overall experience and enjoyment of the headphones.

Build Quality​

The Caldera follows suit with other ZMF headphones in terms of fit, finish, and build quality. That is to say, excellent. Since I reviewed the Verite and Eikon, the ZMF headband has been slightly improved. It is now wider and seems to distribute the weight of the headphones much better. I found it very comfortable for long listening periods. The Calderas weight will depend on the wood used but this pair I have for review in the stock option comes in at around 500 grams. Although the Caldera is not as comfortable as the Meze ELITE, which is a class leader in this area, I had no problems with the Caldera’s comfort over the review period. The 500 grams isn’t too much, and it is distributed nicely with the new headband design. The Caldera comes with the ZMF stock OFC cable, a pair of stock pads, and a pair of your personal choice of pads. The Caldera have a 60ohm impedance, and 95 dB/mw, so they are really quite easy to drive, especially compared to something like the HE6 or the new Modhouse Tungsten’s. One thing to mention is that if you have other headphones in the ZMF lineup which are high impedance dynamic driver based, and also have an amp specifically for them (say a low power OTL Tube amp) and want to acquire a pair of Caldera, it may be worth trying out other amping options with the Caldera. Sadly I do not have any tube amplification currently, but I did experiment with a few different solid-state options, and the Caldera seemed to enjoy a healthy amount of power and current. With that being said, I must note that the Caldera is fairly easy to drive overall, and will work with a large amount of amps. Some experimentation here is worthwhile, but it doesn’t need to be a power monster as it might with some other current flagship planar magnetic headphones.

Pad Options and Mantle Mesh​

Now, let’s talk about the various pad options for the Caldera. For this review, I had pairs of the following

-Caldera Stock Leather

-Caldera Thick Leather

-Caldera Thin Cowhide

-Caldera Suede

-Caldera Thin Ultra Perforated

-Mantle Mesh (not a pad, explained below)

Caldera Stock Leather: The stock pads ended up being my favourite out of all the options I tried. They provided the best impact and slam, whilst also dialing up the soundstage depth and holographic 3D nature of the Caldera. Their negatives were that they shrunk the soundstage slightly, and also the overall image size shrunk slightly. The stock pads also provided my favourite tonal balance, being mostly neutral with a good balance overall. I also preferred a slightly low-shelf increase applied via EQ with the stock pads, but that is entirely personal preference-based, so I would recommend a bit of experimentation to find what works best for you.

Caldera Thick Leather: These pads actually ended up being my least favourite out of all the options. They slightly increased the low mids area and perceived warmth of the Caldera. I felt they didn’t really add anything of note to the soundstage and imaging of the headphones, but caused a loss of that depth of soundstage and holographic 3D nature I enjoyed so much with the stock pads. With all that being said, I read an impression on a forum thread recently that someone prefers the Caldera Thick pads, so as always, personal experimentation is key here, and finding what works best for *you.*

Caldera Thin Cowhide: The Caldera Thin Cowhide pads were my second favourite pads out of the ones I had here for review. They opened up the image size and made everything sound slightly larger and grander. You lose some of the depth of soundstage that you have with the stock pads, but it is a trade-off for the larger overall image. I also found the cowhide helped bring out some of the detail in the treble, whilst not increasing the perceived amount of treble, which I found surprising due to how thin the pads are. You do lose a slight amount of perceived low end with the thin cowhide pads, but again I increased this with EQ so had no problems with that.

Caldera Suede: The Caldera suede pads off the bat are the most comfortable of the pad options, which is pretty standard for me as I always seem to enjoy the feel of suede vs leather. In terms of sonic performance, the Suede Caldera pads reduce the resonance of the Caldera sound, making everything sound slightly more dry and well separated. You lose some low-end impact and slam with these pads, but the soundstage does open up and the overall image size is larger, similar to the cowhide pads. I don’t think I would choose the suede pads as my main pair of pads for the Caldera but they would make a very compelling secondary option if you plan to only have two pairs of pads (the stock being the other pair.)

Caldera Thin Ultraperforated: The ultra-perforated pads are interesting. You definitely lose a lot of what the stock pads bring to the table, in terms of that holographic nature and soundstage depth, but they open up the airyness of the treble, whilst also increasing the image size. They don’t sound as dry as the Suede pads but do seem to very slightly increase the perceived amount of detail present. I went back and forth about these pads more than any of the others. I don’t think I would choose them as a primary or even secondary pair, but if you are curious they do offer some interesting qualities if you are looking for a good third option.

Mantle Mesh: The Caldera can also use what ZMF has called the “Mantle Mesh.” This is a $20 dollar extra which is applied directly over the driver by the user. What the Mantle mesh does essentially is create an effect of extra dampening of the driver, reducing the upper mids and treble frequencies. When I received the Caldera, I hadn’t realized that the Mantle Mesh was installed, and I found the upper mids and treble overly attenuated and thought it was a fairly dark stock tuning. Of course, once I realized the Mantle Mesh had come installed stock, I removed it and was greeted by a much more agreeable (to me and my ears) stock tuning. If you are someone who is particularly treble sensitive, this could be an absolute lifesaver of an upgrade, and would highly recommend it if you struggle with highs and upper mids of the Caldera. For the average person, I’m guessing it would simply blunt the sound too much, and make things too dull and smoothed over. The mantle mesh is a really great idea for certain people and could take the Caldera from an “ow! that’s so bright” to “this is awesome” experience.

Conclusion​

Overall, the ZMF Caldera are a really great pair of headphones. They seem to be the culmination of the entire history of ZMF headphones thus far. From humble Fostex T50 mods to a bespoke in-house designed planar magnetic driver-based headphone, it’s really been neat to watch ZMF grow and continue to innovate. The Caldera has all the hallmarks that ZMF has become known for – Artisan Wood cups and distinct tunings, All done in-house by a team of people who themselves headphone enthusiasts. I sadly haven’t every ZMF headphone, but I have heard a few and the Caldera is certainly my favourite thus far. It is the highest performing in terms of technical performance but is also simply fun and enjoyable to listen to. I found myself going back and listening to old favourites simply because they were great to hear again with the Caldera. The Caldera can be tweaked via pads, and the Mantle Mesh, to your personal preference, and if you don’t mind waiting for a release date and spending a bit more, there are all sorts of cosmetic options for the Caldera, so finding one that suits you in terms of looks shouldn’t be too hard. Personally, I really like the stock-aged oak with coffee gold, but the sheer variety of the woods in the stabilized releases is pretty amazing. The Caldera is less expensive than a lot of the top-of-the-line flagship headphones these days at $3500USD retail, but offers technical performance coming close to many of them. On top of that technical performance, it has its own unique sound signature that is incredibly enjoyable, whilst having some of the best build and support on the market. Overall, I really enjoyed my time with the Caldera, and I definitely give it a thorough recommendation, especially if you are looking for a planar magnetic flagship headphone, but want something a little bit *different.* Awesome job Zach and the team at ZMF!

Disclaimer:

I approached Zach Mehrbach, the founder and designer of ZMF to ask if it was possible for me to review the Caldera as these headphones really piqued my interest. I have been in the hobby for several years and heard almost all flagship headphones. The last 19 months I enjoyed my Meze Elite, which I prefer to several other, even more expensive headphones. After some emailing, Zach kindly lent me a Caldera for a few weeks. He said, in many ways he likes enthusiast reviews more as these are often more honest and more helpful. I hope this review will qualify as that.

Allow me to skip ZMF history, and topics that were covered hundred times in other reviews and are easy to google. I will only focus on my experience with the Caldera, in a slightly more subjective, but occasionally objective way.



Background:

I love my Meze Elites for their easy-going nature, big soundstage, exceptional comfort and sweet, natural tonality. I enjoy the Elite more than I enjoyed the otherwise excellent Final D8000, fantastic T+A Solitaire P, the famously perfect HiFiMan Susvara or the fast and neutral Audeze LCD-5. Some of these headphones edge out the Meze Elite in certain technical aspects like speed, bass definition or resolution, yet as a whole package I enjoy music through the Elite more. To me, on the right audio chain the Elites are resolving, fast and technical enough, especially with the new angled earpads, while they offer a rare level of musical engagement. This is what the Caldera came to face and challenge.



My audio chain and other amplifiers with the Caldera:

After owning several good delta/sigma DACs like the Chord TT2, RME ADI-2, and great solid-state amplifiers like the HeadAmp GSX Mini, BrystonBHA-1 or iFi iCan Signature, I turned to R2R DACs and tube amplifiers. I find that both the ladder DACs and vintage tubes offer a more natural and lifelike sound making it difficult for me to go back and enjoy the more digital flavour of delta/sigma design or solid-state amplification. The caveat is, that you need to reach a certain level of R2R DACs and tube amps in order to avoid a significant loss of resolution, detail retrieval and speed that entry level models suffer from.

My current audio chain: the EverSolo DMP-A6 is the cleanest sounding streamer I heard. I run Qobuz which I find superior sounding to Tidal. The EverSolo feeds my Musician Pegasus R2R DAC which has been upgraded with a SR Purple Fuse. The upgrade to me enhances clarity. Balanced silver cables lead to my Cayin HA-3A transformer coupled tube amp with NOS tubes. I found the HA-3A a bit lean with stock tubes, so with my current vintage tube set I added warmth, a more natural tone and most of all better bass extension, bass definition, control and body. (Mullard M8136 CV4003 12AU7 (old logo); Brimar 6V6GT Black Glass D getter; GE 22DE4.) My headphone cable is the Effect Audio CODE23 flagship copper cable which to me is the most detailed and clean sounding copper cable I have heard with excellent, clean and impactful low frequencies.



Some Caldera owners say that these headphones sound the 'best' on good solid-state amplifiers. Others say the sound is fabulous straight out of a simple DAP or portable amp. I had a chance to plug the Caldera into many great and pricey amplifiers at London CanJam, and found that they indeed change with different amps, but I would not always call the change an improvement as you spend more. Synergie is more important than the price tag.
I also think, it is untrue that the Caldera needs solid state amplifiers to shine. These headphones are equally phenomenal or even better out of some transformer coupled tube amps. OTL amps however are better to be avoided due to their high output impedance.

All that said, my favourite combo with the first planar ZMF was the Holo May KTE R2RDAC and Holo Bliss amplifier. They do a fabulous job in achieving a natural sound without tubes. I actually preferred this stack to the three times more expensive dCS Lina. On the Holo combo there was great spaciousness, fantastic weight, speed and impact with a pitch-black background. The Caldera on this stack offers one of the best bass experiences you can have with any headphones on any amps including the Abyss 1266TC.

While my favourite pairing was the top Holo stack, I personally prefer my fine-tuned little tube system versus other popular and pricier d/s and solid-state combinations like the Ferrum OOR/Wandla or the HPA4/DAC3 stack for example. I am not missing out on bass in my system and the sound is just more natural.



ZMF Caldera vs. Meze Elite:

This review will be a close comparison to my Meze Elite, so let us start with the main similarities and differences. They are similarly tuned headphones in a way that they both aim for ultimate musical enjoyment instead of chasing the last five percent of details or pre-set frequency targets. Both headphones are on the warmer side of neutral, at least when it comes to flagship level headphones. They are both musical and engaging with good bass.

That said, to me they are a lot more different than similar, unalike to a much higher degree than expected. The biggest difference is in their nature; the way they represent and portray music. The Elites are the ultimate long-term listening, kick back & relax kind of headphones, the Caldera is a lot bolder and more dynamic, offering a more colourful and more intense listening experience. As we progress with the review, I will shed more light on these differences.



Build and comfort:

Build quality and comfort are exceptional on both of these headphones. ZMF has a more rustic style while the Elite is a modern beauty. Different schools, equally impressive results. The Elite (Empyrean) set a new standard in headphone comfort which is hard to beat and they are often labelled as the most comfortable headphones on Earth. The Caldera is comfortable too, but the Meze wins here. The biggest aspect of this better comfort is sheer weight. The Elite officially weighs 430g, my set is 435g on the kitchen scale. ZMF declares the stock Caldera weight between 490-550g depending on wood variety and headband material. My aged-oak Caldera is 525g. This 90g (~20%) weight increase is noticeable, so unlike the Elite, the Caldera will not disappear like a cloud around your head. They are comfortable enough, and this 500-550g is still within comfort limit for most people who like to listen to music for hours in one go. To me the Caldera is comfortable, but I would not want it to be any heavier.

Sound:

Technicalities, general tonality:

I think, it is safe to say that on technicalities these two headphones are quite even, yet there are some significant differences. When it comes to resolution and fine detail retrieval, they are on a very similar level, but I think the Elite has the edge there, at least with the new angled earpads. The Elites with their laid-back character sound softer, airier and lighter; more ethereal and delicate. The Caldera is lively, energetic and a lot more forward.

The Meze flagship has more air and as a result, the upper frequencies breathe better. Elite's soundstage is noticeably deeper and a lot taller. Width is great on both headphones; the Caldera might even sound a little wider. On all the ZMF earpads, except the thick leather pads, I found the presentation a little too forward, making me feel I am too close to the stage. To me this sensation becomes the strongest on the thin Caldera pads. I will go into the differences on earpads soon, for now let me just say that for my taste I find soundstage depth ideal on the thick ear-pads, but the Elite's perceived stage is still a little deeper.



Within the illusionary space, created by our brains, the notes are exceptionally well-placed on both headphones providing a nice 3Dexperience. Imaging is great in both cases, although they do it in a slightly different manner. Elite's 3D space somehow feels a little more coherent, while the Caldera separates, pulls sounds apart a bit more. It is not that there is not great separation on the Elite, but the Caldera's separation somehow feels more obvious and clearer. This can be good or not that good, depending on the music genre and recording. (Examples for this in the 'example tracks' section.) On psychedelic ambient, trance and EDM tracks this separation is a win for the Caldera, on small acoustic music groups sometimes this can sound a tiny bit overdone.

Tonality is similar on both headphones, slightly warmish neutral. The Caldera is more coloured and intense, the Elite in comparison can sound more neutral and almost slightly drier in a way. The Caldera's most neutral tuning is with the stock pads, all other pads add some extra colour. This colouration is tastefully done, never intrusive and very enjoyable. Just mind, these are not neutral studio headphones (nor are the Elites).

Another big difference between these two contenders is the body, weight and impact of sound. The Elite is smooth, airy, polite, delicate, easy. Caldera is punchy, energetic, the notes have more weight and they hit your eardrums with more impact. This I find very entertaining, satisfying and enjoyable. I think, this is one of the main characteristics that helped to find a fitting name to the headphones: a caldera on a volcano is colourful, alive, energetic, powerful, warm.


Photo of a caldera. Source: Dreamstime

With the right earpad choice this vibrant nature can be tamed a little bit (thick pads for me or suede pads for others), making the Caldera suitable for long-term listening even for those with more sensitive ears. With the stock pads or the thin pads, I always needed a rest after a couple of hours, but with the thick pads I am fine all day. This liveliness is a big positive for a lot of listeners, but the Elite's softer and more gentle presentation will be valued by many as well. With the Elite you can just relax, and for late night listening it might be the better, more ear-friendly choice. The Caldera grabs your attention and entertains.



Speed is a win for the Caldera, pace, rhythm and timing is just sharper (in a good way) and more precise on the ZMF. When these precise notes have weight and impact, that can lead to a whole lot of fun, as the Caldera's tone is warm and organic; unlike some more neutral/brighter speed and detail monster flagships where this sharpness combined with brighter upper frequencies can quickly become bothering. The Caldera is dynamic without trying to stab your eardrums.

This dynamic and lively nature makes the Caldera the most dynamic sounding planar headphones in my experience. I love planar headphones, but many of them can sound a bit weightless, less focused lacking true body and impact. Up to now, for me the Final D8000 was the most dynamic sounding planar with its circular AFDS drivers. The bass on those is excellent and have some dynamic driver characteristics. The Caldera for me exceeds that experience as the whole sound is just a lot closer to dynamic drivers while offers all the positives only planar transducers are capable of reproducing at this level: bass extension, bass presence, clarity and speed.

Earpads:

ZMF at present, offers five different earpad choices for the Caldera. These are advertised as 'fine-tuning' options, but to me they actually change the sound quite significantly. Of course, you are still listening to the same headphones, but many of the characteristics can be altered. It is absolutely worth experimenting, as if you did not like the Caldera with one pair of pads, you might like them with others. There is not one best option, you have to find what suits your taste and ears the best, these are my impressions.



Stock:

these are the safest, best balanced and also the most neutral option. They show off the Caldera's strengths perfectly: punchy, dynamic, speedy and clear. Soundstage feels adequate in size, although it is a lot more forward compared to the Elite. After a couple of hours, depending on the music, I find that the upper-mids/treble can become just a little too intense on them.

Thick:

these bring a bit of extra warmth with ever so slightly elevated mid-bass. Mids and vocals benefit from this, resulting in a slightly richer texture. Treble is politely smoothed out to a very comfortable level. Soundstage feels the biggest: widest, deepest. There might be a slight loss of a few percentages of clarity and punch compared to the stock pads, but those qualities are there in abundance, so it does not feel like a compromise at all.

Suede:

these smoothen and soften the whole sound. Soundstage size is comparable to the stock pads. To my ears with these earpads we lose too much dynamics, speed and punch; the note edges become too rounded and soft. Bass punches lose some energy like putting a blanket on drums.

Thin (cow hide):

to me there is a significant soundstage loss with the thin pads, especially on depth. These are the most forward sounding pads, almost like I was standing on the edge of the stage. Bass punch is great, but somehow the upper frequencies feel more uneven and the whole sound a bit flatter.

Thin (lamb):

these are very similar to the cowhide thin pads, but they do everything in a more polite way, they are not as drastic.

I quite like the stock pads, but eventually settled down with the thick pads. All other pads to my ears take away too much from the Caldera's stock character and/or capabilities.



Mantle mesh:

The mantle mesh is a simple and affordable extra dampening layer that the user can easily apply under the earpads. They meant to dampen treble frequencies for those who find them too pronounced. Zach said, 95% of people are fine without them, but one in twenty might find the mesh useful. Our anatomically different ear-canal shape means we do not hear high frequencies the same way, there can be a 20 dB (!) variation.

I found that the mantle mesh with the stock pads does exactly what it says on the tin. The highs are dampened, toned down, but lower frequencies are unaffected. This might be the ticket for those who want to love the Caldera but just found the upper frequencies slightly too pronounced. For me, the mantle mesh with the stock pads did bring some benefits but took away too much treble detail and liveliness. I still found it an enjoyable sound, just not my choice.

On the other earpads (thick) to my ears the mantle mesh just took away too much from the experience, this combination is not something I would want to listen to.

My ultimate choice after trying all the combinations was the thick pads without the mantle mesh. My number one reason for this is the enhanced soundstage, especially depth. I like a bit of distance between me and the musicians, to remain in the audience and not to climb up on the stage. I also enjoy the slight bass emphasis on the thick pads, while it is hardly taking away anything from the excellent and clean bass impact of the stock pads. Upper mids and treble are a little bit smoothed out, but they still have some sparkle and more details compared to the stock pad/mantle mesh combination.



Bass

Bass is wonderful on both the Elite and the Caldera, but I will not tease you here too long, it is a win for the Caldera. My biggest criticism towards the Elite was always that slightly softer and more politely presented bass which is inherent from the Elite's natural and more laid-back tuning. Do not get me wrong, there is bass quantity and punchy impact on the Meze flagship, just in a more sophisticated and less 'muscular' manner: a little bit like how a Bentley accelerates versus a Lamborghini.

Caldera's bass has more weight and speed. I always enjoyed bass weight and impact more on the LCD4 or Final D8000 compared to the Elite, but those do not have the spacious, airy and natural upper-mid/treble of the Elite. The problem is, you cannot have everything, so eventually I chose the Elite as I very much enjoy this airy, natural and lifelike sound with still a very good bass and exceptional engagement factor. This airy and natural sound usually comes with a soft, diffuse, less focused and/or less impactful bass presentation, like on some oval HiFiMan headphones. The best balance for me between a weighty, impactful bass and natural, airy upper frequencies has been the Elite so far.

Caldera's bass is punchier than the Elite's, it is more physical, more visceral, yet not overblown. Bass is flatter but very speedy and impactful on the stock pads. The thick pads add a little more mid-bass to the picture. In both cases overall bass performance edges out the Elite for me, and even surpasses the fantastic D8000. Being a 'dynamic flavoured' planar, the Caldera does this with natural, open and relatively airy upper frequencies. Not as naturally airy and not as open as the Elite, but enough for me to equally love the overall balance and presentation on both headphones.

Psychedelic ambient or trance is an otherworldly experience on the Caldera: 3D sound with visceral bass impact as if you had the cleanest subwoofers attached to your head.



Mids:

Mids sound organic, they have an excellent warm and lifelike tone; but they are not as shockingly outstanding as the bass performance. Compared to the bass and treble, mids are ever so slightly recessed. This becomes apparent, when on certain tracks the background instruments have as much or even more emphasis as the solo singer in the centre. It is never to a bothering level, but present when comparing the same track on the Elite. (See 'example tracks' section.) On the Elite the focus stays on the singer and the supporting instruments remain more in the background. Everything is audible on the Elite too, just the emphasis and focus feel slightly more accurate for certain genres on the Meze. That said, not always the most accurate presentation is the most entertaining.

Both the Elite and the Caldera have beautiful mids with a good sense of realism and lifelike tonality. To my ears vocal and fine intrument texture, micro-resolution are somehow a bit better on the Elite, but speed and clarity are superior on the Caldera. Caldera sounds more forward and is more intimate due to the slightly less air and smaller stage in comparison. I can enjoy both mid presentations, ultimately to my ears they are equally good, a little bit like roasted or fried potatoes.

Treble:

While treble is smooth and natural on the Caldera with some sparkle, to me the Elite is winning here. The airy and open nature of the Meze flagship helps the upper frequencies to come across even more naturally; perhaps a little brighter but more ear-friendly and less intense. While the treble on the Caldera is still neutral/warm, there is a little more 'bite' to it due to the more energetic nature of the ZMF planar. The treble presentation can be a win either side, depending on the listener's taste. I am relatively treble sensitive, but never really had a problem with the treble on the Caldera, at least not with brightness or sharpness. It is a natural and rounded sounding treble.

On the stock pads, the upper-mid and lower-treble area can become a little overwhelming after a couple of hours, but not because it is sharp or bright, simply due to the sheer energy and intensity this headphone has in general. This for me was completely solved with the thick pads. Others might find the mantle mesh or the suede pads helpful. For the vast majority of people, the stock treble will be absolutely fine.



A few example tracks:

Gaudium– How can I tell: the bass on this track with the Caldera is something to experience, especially what comes after the fourth minute. (If you liked it, try this one too: Gaudium– Nn.) This is where the Elite or pretty much any other headphones (maybe with the exception of the 1266TC and D8000) cannot really hold a candle.

Offspring– Smash: I used this track for treble testing as it gets very intense. This is what I find too much with the stock pads, but fine on the thick pads (or with the mesh under the stock pads).

Aurora– Conqueror: another example for treble intensity.

Hans Zimmer – Mountains: an example track for grand spaciousness. This I find more enjoyable on the Elite, Caldera's space feels a little more limited in direct comparison.

Sowulo– Wyrd Webba: while both headphones are very good here, the Elite to me somehow gives back a slightly more resolving, a little more natural texture to instruments and voices, perhaps partly due to the bigger space/reverbs. The Caldera's intensity and energy is closer to the track's true nature though.

Telepopmusik– Genetic World: percussion is airier and more natural on the Elite, but bass is more focused on the Caldera.

GiulianoCarmignola II.Allemande Bach Violincello Suit: with this track I find that staging and instrument timbre is a little better on the Elite. It is true nitpicking between two great choices, but the slightly richer reverbs make the sound of the violincello a bit more believable to me on the Meze, while it is still very good on the Caldera. Imaging also becomes a little bit strange on this particular recording. While I see a coherent image on the Elite, Caldera pulls things apart a bit, namely the violincello itself and the breathing of the musician. On the Elite the musician breathes in the centre of the stage as he should, but on the Caldera the breathing somehow comes more from the two sides, while the violincello is in the centre: just a little odd.

Norah Jones Come away with me album (192kHz/24bit): both headphones are beautiful, but what I found is that the vocal on the Elite is more in the spotlight while the instruments are supporting the singer. On the Caldera somehow the instruments become equal participants to the singer.



Conclusion:

What is my conclusion then? In a nutshell, these are my two favourite headphones on today's market. The negatives I mentioned about either of these headphones were nitpicking between two champions in direct comparison.

Zach Mehrbach and Antonio Meze are both brave enough to diverge from mainstream trends, remain unique and follow their own paths. These two headphones have a bit of a character, but for me that is what makes them loveable, enjoyable and engaging. To my ears they both do everything well, and they do different things exceptionally well. Bass, energy, liveliness, organic sound, speed, impact are the Caldera's strengths. Easy listening, coherence, fine texture, natural and airy sound are the strengths of the Elite. I could live with either of them as my only headphones and would pick them over pretty much any other flagships in August 2023.
If it was possible, I would try to combine the Caldera's sublime bass performance with the Elite's natural openness and also find a middle ground between the ZMF energy and the Meze delicacy. For now, I am enjoying both and delaying the tough decision: which one to own long term.



In the Caldera, Zach has managed to combine the magic of his popular dynamic driver headphones with the advantages of planar technology, namely a deeper bass extension, higher overall clarity and superior speed. The Caldera is a true masterpiece with character and personality that many will find endlessly enjoyable. Thank you, Zach, and I hope you will gift us many more wonders in the forthcoming decades!

The Caldera has been reviewed often and in detail since its launch, so consider this my "update" on the Caldera, focusing on the sound of the new Mantle mesh; the sound of various ZMF earpads for this headphone; and a comparison of the Caldera with another open-back planar, the Final D8000.

Background: My first planar headphone (my first serious headphone, period) was the ZMF Ori. The Ori suited my tastes perfectly and introduced me to great planar bass. When open-back headphones became a priority, I assumed it wouldn't be difficult to find an open-back planar as good as the Ori. I was so wrong. Five years and six open-back planars* later, I finally landed the Final D8000 with the D8000 Pro's "G" pads. It's a keeper. Then the Caldera launched (an all-new ZMF planar!) and I had to hear it. My first loaner didn't work out (medical issues), so a couple months ago I purchased a coffee-stain oak Caldera, the subject of this update. Since then this beautiful Caldera has been shaking up my audio world.


Comfort
The comfort of ZMF headphones has become consistently excellent in recent launches, thanks to the redesigned headband. Yes, the Caldera has large wooden earcups with metal screens and hardware. And yes, it's relatively heavy. But thanks to this headband's padding and comfy, spacious earpads, the Caldera is one of the most comfortable headphones I've ever used. I just don't feel the weight of it.

Visual Design
ZMF's earcup screens have steadily become more interesting and aesthetically pleasing to me in recent years. I think the Caldera's screens are the best ZMF ever did, allowing the Caldera to compete favorably with the Meze Empyrean and Elite, which also have large, beautiful screens. I commend ZMF for designing the Caldera screens with a gentle but noticeable concavity (inward slope) at the center. This restrains what would otherwise be a larger exterior radius of these (already large) earcups. It's a subtle touch that visually streamlines the earcups and makes them somewhat easier to handle.

Beyond its screens, the Caldera is the first open-back planar I know of that marries cutting edge planar design with ZMF's classic, heirloom wood craftsmanship. A number of high-end open-back planars are handsome; this one is simply beautiful to look at.

The Caldera Sound
With the sturdy, comfortable stock pads (the best earpads I've ever encountered), the sound of the Caldera is impressive, often surprising and always involving. The Caldera does four things about as well as any other planar (any other headphone, period): resolution; soundstaging; dynamics; and timbral accuracy. I suspect we can thank ZMF's ADS (Atrium Damping System) for the soundstaging, which outdoes every other planar I've heard by a wide margin. And we can probably thank ZMF's CAMS (Caldera Asymmetrical Magnet Structure) for the rest.

• I've heard other TOTL planars with high resolution, a few maybe even more than the Caldera's, but sometimes resolution brings brightness and a lack of musical realism, sounding unnaturally, excessively detailed (at least to my ears). The Caldera's resolution is very high, with impressive "technicalities," but there's little if any sonic toll. There is a dash of warmth here, supported by deep, foundational bass that gives the sound natural weight, pulling it back from the top-lit, edgy tonality that sometimes accompanies high resolution. I hear the Caldera as "ZMF neutral" done right: it facilitates analytical listening (for those who want that), but always lets the music through.
• Soundstaging is not a quality many planars excel at. Dynamics tend to pull ahead here. But the Caldera is different. Its soundstaging is mind-bendingly good. I never once put on this headphone without noticing how well it renders acoustic space. I've heard two other headphones that use the ADS, the Atrium Open & Auteur Classic; the Atrium has the best soundstaging I've ever heard, period, while IMO the AC and Caldera are neck and neck for next best. Most planars don't come anywhere near the Caldera in soundstaging, although some TOTL planars produce a large, diffuse soundstage that is quite pleasing.
• Dynamics often are a strength of planars. I find the Caldera has better macro- and micro-dynamics than any other planar I've heard except possibly the big Abyss. The Caldera has "jump factor" to spare. This brings to mind the ZMF Eikon, one of the most dynamic headphones I've heard. I think the Caldera is even better. With music that gets loud and crazy, I really need a seatbelt and roll bar to use this headphone.
• Timbral accuracy isn't something I noticed much in planars. It didn't seem like one of their strong points. However, I consistently notice excellent timbre in the Caldera; it nails the inherent sound of every instrument and voice, making them sound like they do IRL. That is exceptional performance by a planar driver.

Considering all four of these things, what I hear from the Caldera is an advance in the evolution of planar sound: the deep, pressurized bass, excellent dynamics and high resolution of the best planars, along with soundstaging and timbre that are usually the province of top dynamics.

Hearing Into the Mix
Hearing familiar tunes with the Caldera, I discovered its high resolution and accurate timbre synergized, allowing me to easily "hear into the mix" and distinguish each track's particular tonal values: warmth vs cold, bass-rich vs not, compressed vs not, natural ambience vs EQ'd ambience, etc. I've never heard these sonic cues so clearly before. The Caldera definitely changed how I listen to studio recordings.

Examples: On the superbly engineered "Morph the Cat" by Donald Fagen, the Caldera makes it evident that Fagen constructed a dense, thick, bass-rich sound, anchoring each track from the bottom up, with the concussive title track employing multiple bass instruments of different types to do it. By contrast, 1960s Blue Note jazz dates deliver slight warmth and bell-like midrange clarity, ideal for conveying instrumental tone. And minimally miked & mixed classical recordings put instruments and voices in large, reverberant spaces with little if any sonic manipulation.

With the Caldera, I can appreciate not only the performance and the music, but also the quality of the mix itself. If I was a music studio pro, I'd prize the Caldera for how it reveals the mix without sounding "forensic" or cold.

Tonality
The usual bass/midrange/treble discussion is simple with the Caldera. I hear it as relatively flat from bottom to top with no significant dips or peaks. Because the typical shallow dip in the mids to upper mids isn't present here (at least, not to my ears), the Caldera has a somewhat midrange-forward sound. That's OK because these mids are so expressive and detailed. Note that the Caldera's bass capabilities are so good that with music having strong baselines, it a borderline-bass monster … but only when the music calls for it.

The Caldera's straight-ahead, neutral sound means any peaks in components or music (upper mids or lower treble) come through clearly. That can be problematic for me because I'm more treble-averse than most. That's where the new Mantle mesh comes in:

• My first Caldera (a loaner received late last year) had the original mesh. When there was a lot of energy in the upper mids and lower treble of music, I really heard it. Not a constant thing by any means, but it could become too much of a good thing by interrupting this headphone's otherwise smooth and engaging sound profile.
• My new Caldera shipped with the Mantle mesh installed. I'm not able to directly compare the 2 meshes, but my ears tell me those periodic energy peaks are smoother and less abrupt with the Mantle mesh. Not a huge difference, but a meaningful one for me (I'm more treble-averse than many).

Earpad Rolling
I have four sets of ZMF earpads made for the Caldera. All are perforated. The sonic results of pad swapping were intriguing (and in one case, a revelation) without flat-out ruining the sound, as I've done rolling aftermarket pads on other headphones. The availability of high-quality OEM pads is an real value-add for users inclined to explore different flavors of Caldera sound without resorting to EQ:




Amps & the Caldera
The Caldera is no HE6 or Susvara. Any reasonably powerful amp will get it going. The three solid state amps I tried it on (Violectric V281; Monolith Liquid Gold X; Cavalli Liquid Carbon v2) did very well with the Caldera, as they do with every other planar. The real surprise was my transformer-coupled tube amp, the Icon Audio HP8 (with NOS tubes), which handled the Caldera perfectly and nosed out the V281 for best sound of all four amps.

As with every other planar I've had here, the challenge isn't reaching the desired volume; it's getting the headphone to lift-off, to sound as good as I know it can sound. The Caldera makes this relatively easy. It's not a particularly amp-picky headphone. However, its very high resolution can cause surprises. I heard differences between these four amps more clearly than usual.

The Caldera does scale to a degree with increasing amp power and design sophistication. But it sounds so impressive with all the amps I tried, that I suspect it'll work well with any amp having decent power. This is not a headphones that forces you to 2nd-mortgage the house so you can afford the one unicorn amp it actually sounds good on. For a headphone with such obvious TOTL sound quality, this as a very user-friendly quality.

Caldera vs Final D8000 ("D8K")
For this comparison I used my favorite pads (lambskin thicks) for the Caldera. The Final D8K is Final's former TOTL planar, recently replaced by the D8000 Pro, which is said to have a bit less bass and more energy in the upper mids and treble than the D8000. I replaced the D8K's miserable-feeling stock "F" pads with the Pro's "G" pads, which have perforated alacantra-type material on the face that touches the face. I found the G pads increased both the comfort and sound quality of this headphone. I'm laying all this out because my pad selections may have skewed the results of this comparison to an extent

(Caldera)

• Instrumental separation on Caldera is outstanding. Yet at the same time, the Caldera fully conveys the cohesion of multiple instruments playing together in real time and space. To hear the parts so clearly conveyed as well as the organic whole is something special.
• Caldera bass is a thing of beauty. When you listen to music with little or no deep bass, you'd never suspect how much power this headphone has in the tank. But then cue up a tune with a strong bass part (any bass instrument), and there it is: bass with a heavyweight punch as well as great tonal fidelity, making it easy to distinguish the timbre of upright bass vs electric bass; synth bass vs string bass; etc.
• The Caldera's soundstaging is really bonkers: wide, tall, in front of my head, though my head, sometimes even behind it. There's nothing "stretched" or unreal about the soundstaging. It sounds quite natural, albeit more "present," spatially separate, and distinct than other headphones.
• The Caldera can do "pretty" tone all day long. As great as the dynamics and bass are, this is a headphone that will fully convey the sheer beauty of a string section, a choir, or a solo instrument. When the music is beautiful, the Caldera lets the listener hear the beauty. This is not a characteristic I associate with headphones having as much resolution and clarity as the Caldera, but there it is, easy to hear.
• With stock pads, the Caldera is a powerful, detailed, dynamic headphone that also has real soul. It really swings when the music does. Dynamics with the thick pads are slightly less, but still more than most headphones can manage.

(D8K)

• The D8K requires a little less power than the Caldera. The D8K's perspective is somewhat more distant overall.
• The D8K's soundstaging is in another world from the Caldera's. It pleases me and doesn't sound deficient, but it can't compare with the instrumental separation and spatial clarity of the Caldera. The D8K creates more of a Left/Center/Right soundspace.
• The D8K's dynamics are well above average. This is a very punchy sound. But the Caldera is simply better, with true "jump factor" dynamics. If I'm not expecting this or that loud transient from the Caldera, it might lift me out of the chair.
• D8K's bass is outstanding, absolutely competitive with the Caldera's. D8K's bass sounds a touch "thicker" and weightier (probably due to the "G" pads), though both headphones have killer bass.
• Though I consider the D8K a very resolving headphone, it's not quite equal to the Caldera there.

Both headphones convet music with power and fidelity. Both sound musical, though in somewhat different ways; neither has a cold, forensic sound. Comfort is no contest. My Final D8000 has adequate comfort (better than the stock D8K)—but the Caldera is way ahead on comfort. The D8K's tone is slightly "wetter" than the Caldera, even with the thick pads. I happen to like that, but not everyone does…. The Caldera has a little more treble up top, a little more sparkle. The D8K's treble is shelved down a bit. I prefer that. But pads matter in this context: with the thick pads, the Caldera sounds closer to the D8K.

Both headphones please me to no end. These are TOTL planar designs, and while they look and feel rather different, they arrive at pretty much the same place—excellent, musical sound that pleases me greatly. I need both headphones.

Conclusion
The long wait for ZMF's first purpose-built planar was totally worth it. The Caldera is beautiful; has impressive, musical sound; and more or less laps the field with innovative visual and acoustic design elements. Just my 2 cents, but I believe the Caldera will be seen as the planar headphone design to beat, if it isn't already.

I've had the pleasure of an extended review loaner of the $3499+ ZMF Caldera that's been at times on my head and off-times off my head over the course of several months now. It is no fault of the Caldera at all, it just happened to be a rather busy period of holidays, being stricken with illness, recovering, traveling, and just a busy work schedule. But, every time I do reach out for the Caldera, it's been a nice, pleasurable listen that I am going to discuss more in this full review.

First off, I did provide my first few days of listening impressions way back in November prior to the headphone's launch. I was lucky to have been able to get my hands on the headphone to try out from Zach of ZMF himself, and have been holding on to it for quite some time, though sharing it with several members of the Seattle audio community in the months I've had this in my possession.

Each local audiophile auditioner loved what they heard, and I can go more on that later, as I did collect some notes to discuss.

The Headphone​

The ZMF Caldera is Zach's first foray into a custom-designed planar-magnetic driver. Previously, he started the ZMF company on the backs of modifications and improvements to the Fostex T50RP series of planar magnetic headphones. He introduced new internal mods, and his famous and unique wood-cup designs to the headphone and went through a few different iterations, before switching over to custom biodynamic driver-based headphones, and then the beryllium-based drivers of the Verite series.

The Caldera brings him full-circle back to his roots from 2011, when he made his first modded T50RP. The new design here is an 80mm planar driver that has an impedance of 60 ohms and headphone sensitivity of 95 dB/mW. It's not a hard to drive headphone, but it may push your portable gears to the other end of its volume limits than the beginning.

The unit that was sent to me is the standard Oak wood cups with black grills, rods, and chassis. This is the basic model, but as with all ZMF headphones, there are upgraded color and metal options, and limited edition wood runs that are very popular and always look stunning. As I am writing this now, there is a limited run of Bocote and Redheart woods available.



Each Caldera order comes with 2 sets of pads of your choice, and a cable with the termination of your choice. Every order is customized for you, and because each wood piece is unique, you'll get a surprise of how it looks when you open the box. Each one I've seen, in real-life or online, have been spectacular looking, and owning ZMF headphones previously, I've never been disappointed in quality of the build, or appearances of the wood pieces. The Caldera is no different.

The new headband design is more padded than ever and is designed in a way that makes the weight of the headphones feel much lighter than the scale will tell you. For most headphones over 450 grams, I typically feel the weight of them pretty quickly. This one scales at well over 500 grams, but it still feels comfortable for long listening sessions.

The pad options included in this set were the Caldera leather pads and the Suede pads, as well as a cowhide pad that was a bit thinner than the other two. The Caldera leather and suedes were on the thicker side, but are both very comfortable to wear. Each of these have their own unique sound characteristics that I will describe in the sound section later.

The cable included is the new ZMF standard headphone, which is a black-cloth sheathed copper cable comes terminated in the connector of your choice, and meets the headphones with the standard mini-XLR jacks that are normal on every ZMF headphone.

Sources​

I primarily used the 1/4 inch cable with my listening sessions, although there was a balanced XLR cable available in this kit. I did try using that for quite a bit of time early on with my iBasso DX240 DAP, but for the most part, I used the standard unbalanced 1/4 inch cable with my Bakoon AMP-13R and Holo Spring 3 KTE set-up I use for headphones.

Sound Impressions​

Some of the following will be a bit of a re-hash of my prior impressions, but I'll try to add more detail and some sample impressions as I write this, along with some feedback from community members who have also had an opportunity to demo this specific set over the past few months.

The Caldera is a warm-tilted, and slightly-dark sounding headphone, but doesn't stray too far away from what I consider a neutral sound target, at least for a typical ZMF. It's easily the most traditional reference sounding headphone that I've tried in ZMF's lineup, but it also continues to feature a heavy dosage of the ZMF House Sound that has a warm and rich mid-range that is quite engaging and enjoyable, and a sweet treble range that is extended and smooth. The bass extends into the sub-bass fairly well, and is generally linear throughout with a little dip as you go further down to the sub-regions.

If someone took the tonal balance of an Audeze planar (e.g. LCD-4) and a Hifiman planar (e.g. Susvara), and split it down the middle, I'd say you'd land pretty close to what the ZMF Caldera sounds like. It takes the best parts of both, and gives a very well-balanced headphone in its tonality.



I enjoyed using the Caldera a lot with rock music. It's the stuff I grew up on and I always love listening to 90s alternative and this headphone does it quite well, and better than my "end-game" Hifiman Susvara. When I listen to Alice in Chains or Smashing Pumpkins, or even Radiohead or The Ataris, there's just more meat on the bones on a Caldera than a leaner, but more elegant Susvara. The Caldera has more body in the mids and a slightly darker treble range that eases off on the wailing guitars and crashing drums, and gives more thickness to vocals, bass guitars, and kick drums, that help give more raw power to these anthem tracks.

When I put on some Nickel Creek, and their brand of bluegrass music, I still found the Caldera to be quite enjoyable, with a good soundstage, imaging and instrument separation. The band's trio of string instruments sound defined, but don't necessarily have the crispness that they would sound on the Susvara, and trails just behind it on resolution for these very minute details such as the faint strings fading away in the background. But, the Caldera still does a commendable job on resolution and soundstage -- it's just not as open and resolving as the Hifiman flagship that also cost over 50% more.

In terms of planar magnetic headphones, the Caldera is one of the closest to a dynamic driver sound that I have heard. It's still "fast", but the weight of the notes, and the richness in its presentation, along with the longer decay give it a more natural sound than the typical Hifiman planar headphone that have stocked my collection through the years.

Pads​

The pad material options do play a role and a fairly significant one here.



The standard leather Caldera pads have the most neutral sound of the three I had, and provides the most dynamics and punch. The transient speed felt the fastest here, and most intricate.

The suede Caldera pads offered a smoother sound, with a little less emphasis in the upper-midrange and low treble, and more rounded edges and slowing down the overall transient speed.

The cowhide pads are quite a bit thinner than the other two in size, and with this, made a very different sound presentation. I found this one darker in the upper-mids with a treble lift that is similar to the Verite series. I thought this still kept the snappiness of the leather pads, but also gave a more holographic soundstage, but with a much more wonky tonal balance that I liked the least.

More Listening Impressions​

I took these out to a couple audio meets in the Seattle-area over the winter months, post-pandemic, and had a few people I met in the community try them out. For the most part, I think everyone enjoyed what they heard, with some seriously contemplating buying them. Some compared these to the Atrium, another ZMF headphone with a similar tonal balance, but in a dynamic driver configuration.

The Atrium is one of my favorite headphones, and I absolutely loved using them for rock music when I had them on loan from ZMF when they first came out. They were my favorite ZMF at the time, and now the Caldera has surpassed them for me, because the Caldera improves the resolution and its tonality fits my preferences more.



But that said, there were folks who preferred the dynamic driver sound on the Atrium over the planar sound on the Caldera. The Atrium is a little bit richer with a stronger note presentation and longer decay. It's ever slightly darker, and so there were people who preferred this thicker and more relaxing presentation over the Caldera.

There was another listener who really loved the Caldera and has been contemplating buying one for a while now, as an upgrade to the Hifiman HE-6. When this person first listened to it, he thought it was good with the Caldera leather pads, and was already thrilled with it. Then we swapped out the pads with the Suede pads and I quickly observed his smile grow as he listened to them. It seemed like a serious "A-Ha!" moment had occurred! At the time of writing this, he was still deciding whether to buy this headphone or not, but hopefully he'll get to demo this set again in a couple weeks and go from there.

Like I said, of the dozen or so people who tried it, I didn't see or hear any dislikes or even "so-sos". Everyone seemed to enjoy the Caldera. Some still preferred the sound of a dynamic headphone and leaned toward the Atrium or Verite, but all of them really enjoyed that ZMF sound, despite other top end headphones around.

For me, I don't necessarily care one way other the other if it's a dynamic or if its a planar. There's some characteristics that help kind of define the sound of the two, but I find that that is changing as we evolve headphone technology anyway. The Caldera has a lot of carry-over sound that reminds me of a ZMF dynamic headphone, more-so than most other planars. It is a great in-between, and does so with a good all-arounder sound.

Final Thoughts​

The Caldera is a great headphone. It has the ZMF DNA in it -- wonderful wood aesthetics, solid build quality, top notch customer service, and the typical warm and lush, engaging mid-range I've come to expect from their products. For folks that had hesitation on ZMF's tonality in the past, this one, along with the previous release, Atrium, should help provide a different outlook -- it sure did for me, despite being owners of other ZMF gears in the past.

ZMF's much anticipated and lauded first Planar is finally here, and it is a beauty. If you don't want to read this review, then you can stop right here. This is my first 5 star review of any product. Nuff Said! The Caldera is emotional, fun, intelligent, comfortable, gorgeous in white oak, has incredible transience, fast decay; and all while still maintaining the trademark ZMF smooth, and fun sound.

I have not been compensated for this review. I would like to thank ZMF for the opportunity to spend this time with the Caldera. All thoughts are my own, and as usual this review will be a mix of food, music and the full engagement of our senses.

You will not find any measurements, there are plenty of those already. Hopefully, you will walk away feeling a little bit better about your decision to either own or potentially own a Caldera. It is WORTH every penny!

Accessories:
The Caldera comes with the normal ZMF accoutrement. You get a seahorse or wooden case, the headphone, two sets of pads (The Caldera Lambskin Perforated and Caldera Suede Perforated), 2 cables ( I received 2 braided spec cables, but have an OFC and other cables at my disposal), an Ownership Card, Lifetime Driver Warranty and a nice little bag for the cables.

As always, the Caldera arrived without any issue. The packaging is perfect. The headphones are secure and you always feel welcomed to the ZMF family. I cannot understate how important a factor this is in purchasing for me. I don't need the best deal, I just need to feel that my business matters. ZMF exemplifies this! They make every customer feel as if they are their only customer.

Driver's and Damping:
ZMF's first Planar is equipped with an 80mm Planar Driver encased in a carbon fiber baffle to keep weight down. In addition, it is equipped with several traces and pathway patterns all that are gold plated copper instead of aluminum. This seems to have a positive effect on overall weight, and therefore overall comfort. The Caldera tops out at 60 ohm's. In addition, the Caldera comes with the patent pending Atrium Damping System. The ADS reduces back-wave which helps to push air towards your ears giving you a more informed and developed pocket and musical space. In short, it increases the soundstage width and depth exponentially. However, the Caldera does not possess the otherworldly soundstage size as the Atrium, it does work beautifully and helps to create and extremely developed and accurate stage and image. This would make the Caldera the first Planar that I know of to use a damping system from a dynamic headphone. I don't know this for sure, but the addition of the ADS gives the Caldera a very unique flavor and tuning. It makes the jump from dynamic to planar such a comfortable space for a company that started modifying Planar T50's and then became known for their high impedance dynamic designs. To revert back completely in their own way, on their own time and with their own ideas makes the Caldera all the more special.

Comfort & Pads:
Every ZMF comes with their customary strap and crescent strap. They have recently changed to the crescent strap making weight distribution that much better. I can wear the Caldera for hours without feeling any hotspots or discomfort. Weight distribution is even and I have no issues wearing my glasses free of discomfort. The Caldera comes with their new Caldera Pads. Lambskin Perforated and Suede Perforated. They are smaller than the normal Universe, Auteur and Eikon pads. However, they don't feel any less comfortable and as always, pad roll to your heart's content. I personally prefer the Lambskin, just as I do on all ZMFs, but the Suede's offer a compelling sound signature. Per my usual, I find that the Lambskin’s offer a bit more linearity through the bass, with less 150hz hump and a cleaner move into the lower midrange. I also find the Lambskins to provide a bit more sparkle in the treble. I hear this especially with cymbal hits, wind instruments and vocal harmonies. Whereas, the Suede's counter with a more romantic sound. A bit rounder, slower decay and a fuller bass with more emotive vocal presentation. I also find the Suede's to be a tad bit darker coming out of the presence region into the lower treble. As always with pads, YMMV. This is just how I hear it, and what I prefer. Honestly, I love the Caldera with both sets of pads. The Suede's are admittedly a bit more comfortable, compressing into my ears a bit better lending to a smidge better seal. However, I still prefer the overall tonality and voicing with the Lambskin's.


Are these not GORGEOUS? I don't have much to say here, just couldn't waste this amazing shot. The grain is spectacular, the aggregated whole is just on point to my taste and preferences.

Customizing your ZMF:
I would be remiss if I didn't bring up the customization of the Caldera and all ZMF's. You can get an aluminum or magnesium chassis (for an up-charge), different color rods and grills. And the White Oak can be stained to look like vintage coffee with copper, brass or black. As you can see, the pair I have here are the standard Natural White Oak with all black. Sexy! In addition, you can upgrade your cable package. I believe the Caldera sounds best with a silver cable, but the OFC or 2k Copper will still provide you an amazing musical tour de force. I know some complain about their stock cables, but I have not found them to be anything other than easy to use and extremely musical. I love the OFC cable, and in most instances believe that the OFC is enough for a ZMF. However, my Audio Sensibility Silver Statement was the perfect compliment for the Caldera. It let the bass flow a bit lower, opened up the lower midrange, and gave the treble a small dose of sparkle that made the Caldera even more complete. Was it needed? No! Did I love it? Yes! You can also keep an eye out for Limited Edition runs (Kingswood currently), Canjam specials, and the twice yearly special that sends out B-Stocks, Stabilized Variants and woods that might only have 1 or 2 in that form. I am quite fond of all ZMF's in Camphor Burl. I would personally wait and try to score a Camphor Burl during the summer special or ZMF November. As for Janka Ratings, while the wood density will make a small difference, buy what you like the look of first and foremost. All Caldera's are tuned exactly the same and so ultimately buy what you find aesthetically pleasing. I always buy my artisan bread when their is a bit of browning or even a smidge of darkness to the crust. I know that the flavor isn't much changed, but I love the look and it makes it taste better to me. ZMF wood is no different. Are there small changes with wood densities? Maybe. Are you buying something you like the look of first? Definitely! The most important part of the wood will be weight. The denser the wood, the heavier the headphone. A regular white oak will come in around 490 grams. However, they could go as high as 550-575 grams if using an extremely dense wood. So, take into account weight as well while you are deciding on your custom Caldera heirloom.

Sound Impressions:
The Caldera sounds huge, snappy, fast, and balanced. It isn't as fast as my Soltaire P-SE, or the Susvara, but it is also more emotionally charged. It is incredible with Psychedelic Rock, Jazz, Bluegrass, and good ole' Rock n Roll. It is powerful, and the ADS provides front to back depth that enables an incredible sensation, where instruments and vocals are separated within the sound field.

Image Specificity, especially instrumental separation is top notch. All instruments can be heard in their exact space on stage, with enough room and air to discern their exact location. If you have been to Red Rocks, the Caldera provides a similar feel to being at the Rocks. After the rain dissipates, and the stars come out, a warm wind swirls through the amphitheater creating resonance as the sounds bounce off the rocks and back at your ears. The Caldera is doing the same thing. Sounds are swirling around you, the image solidified by the resonance of the wood and the stability of the driver and ADS where the acoustic soundscape makes its way back to your ears accurately and oh so pleasantly.

Like most TOTL planars today, vocals remain upfront in the mix. They aren't as gritty as the Atrium, but they are still emotive with wonderful focus. This I imagine is helped by a treble presentation that is more uplifting than downward sloping.

As always, ZMF goes their own way when it comes to their version of the Harmon Target and Frequency Response. I wouldn't call the Caldera "ZMF Neutral", but it definitely goes its own way. They aren't trying to follow a curve, they are trying to create the most musical, enjoyable and fun headphone that you want to continue to pick up over and over. They do this on their terms, and with the Caldera it works as well as any headphone I have heard. It is not as detailed as the Soltaire P-SE, it is not as fast and ethereal as the Susvara, but I just can't stop listening to it. Their is a noticeable lift around 2-3k and a dip between 4-6 to my ears, which mitigated by a peak around 8k gives the Caldera that finishing touch of sparkle and openness.

The Caldera's most impressive feat is the move from bass to midrange. It is extremely linear all the way down to 20 hz or so, and so clean as it enters the presence region. I don't hear any scooping, just a smooth transition into the midrange. ZMF continues to impress with an articulate, open and beautifully rendered midrange. On Radiohead's "High & Dry" off their album Bends, the guitar is both subtle and gritty simultaneously. Vocals are extremely present, yet emotive. All instruments are placed perfectly and the sound is whole. The peaks and valleys of the song are paced perfectly. There is no slog. It is an effortless reading of a gorgeous song. The same can be said for the Roy Ayers tune "A Tear to a Smile", the titular song off this amazing album. Roy's vibraphone playing is impeccable, its tonality is spot on, and it sounds like a waterfall of sound coming out of every direction, firmly planted in the middle of my head. The sounds are coming from everywhere, yet the Caldera still anchors you to the pacing and rhythm of the bass and down beat drumming. Roy's vibraphone playing must be heard on the Caldera. It is so powerful, evasive and subtle; while remaining completely up front. It is so good, it is all you can discern.

I continue to move through my Roy Ayers collection with the Caldera. Next up was Mystic Voyage. Another song with a funky bass pocket, instrumental subtlety coming from left to right and front to back, and as always, you get a Roy Ayers Vibe's solo that will knock you out of your chair. Thank you Caldera for rendering Roy's Vibes perfectly. I can feel his hands moving, his mallets hitting the metal bars with perfect decay and transience.

Timbre/Tonality:
As with all ZMF's Timbre and tonality are right at the forefront. Timbral Coloration is slightly north of neutral giving the Caldera a beautiful harmonic balance. It is charming, rhythmic, with beautiful pace and timing. Tonality is accurate and the Caldera sounds like music. Is there any better way to describe a headphone than to say it sounds like music? I know when I make a new dish, all I want to achieve is for it to have balance, aesthetics and for it to taste like what it is. The Caldera sounds like how great food is supposed to taste. Accurate, with a bit of alchemy where the customer has to ask themselves; how did you do that? Generally the answer is easier than what people think. Good technique, and a connection to your senses. The Caldera's timbral abilities are exactly that. A bit of science and a bit of magic. All that matters is that the Caldera sounds right.

Staging and Imaging:
This has become my favorite part of all ZMF headphones since the inception of the ADS. There is so much room for the instruments to play patiently and within their own space, that the stage is accurate, lifelike and generally takes on the size of the room. What else can you ask for? I don't want my music to sound like it is being played at MSG when they are at the Fillmore in San Francisco. The staging must be able to take on the instinctive feel of the room size and the space between the musicians. Both the Caldera and Atrium do this in spades.

What I like even more is how well the Caldera handles image specificity. The Accuracy of the instruments, their location on stage, the accuracy of how they come out of each channel, and the balance which gives each instrument its own unique tone and the air necessary for it to have the proper decay and transient snap. Caldera, CHECK!

Select Comparisons:

Caldera vs. LFF Code X
I am going to compare the Caldera to my all time favorite headphone. The LFF Code X. I just recently picked up an original Code X. All is well in the world. Does this headphone compare to the Caldera from a technical standpoint? No! Does it compare with a natural tone and timbral quality? Yes! The Code X's super power is how incredibly musical it sounds. It doesn't have the most technically advanced driver, and the modification is 7-8 yrs old, but this oldie still stands the test of time. The Caldera counters with a faster sound, a better sense of stage presence and overall it is just a more proficient headphone. That being said, the Code X is so good I have a hard time picking a winner. So, a tie it is. This is more heart than head, admittedly.


The Caldera vs The T+A Soltaire P-SE
This one is tough. The Caldera is a more musical headphone with a more physical and enchanting sound. The P-SE is lightning quick, and resolves as well as any headphone I have ever heard. Every aspect of the P-SE is perfectly balanced. Its main fault being that the sound isn't as weighty, and I tend to like my music to be physical. However, when I switch the P-SE from the CFA3 to the Icon Audio HP8 a lot of that physicality becomes more present. It is tough to say which headphone wins. The Caldera has such an alluring sound, but the P-SE is so technically on point that saying one is better than the other is a futile effort. How do I decide if I like the food at The French Laundry better than a Roasted Chicken and Tuscan Bread Salad at Zuni? I can't, I can only appreciate each for their brilliance. Result : Tie!

Atrium & Caldera

I am not going to do a huge comparison between the Atrium and Caldera. They are so different, and if you want to read my thoughts on these two headphones, please read my review on the Atrium. I go in depth and give a detailed explanation of what makes each headphone so unique and great. I will say this. The Soundstage is bigger on the Atrium, but more accurate on the Caldera. Decay is slower on the Atrium and faster on the Caldera. Transience follows the same logic as decay. Which do I like better? The Atrium is my favorite headphone for every day listening. The Caldera is a better headphone technically.




Amplification Select Comparisons:
Before I begin, can you believe the grain on that Caldera on top of the Audio-GD R28? Wow, what a beautiful headphone.

CFA3:

As much as I love Caldera with my normal psychedelic rock, when you hear the Caldera on the CFA3 listening to the Terry Callier show Alive and his tune "Lazarus Man", I realize that the 5 star rating is more than adequate. Terry's vocals are emotive and the performance is transcendent. Flute and Sax solos have fantastic tonality and the song is supercharged by the strong bass, and full band articulation. This album still remains the seminal live work available to Terry Callier fans. This album, this song and the CFA3 with the Caldera is nothing short of spectacular.

The CFA3's dual mono design, golden reference power supply and 16 watts into 50 ohms is overkill for the Caldera. However, the pairing is perfect. The top end resolution is refined, bass is palpable, and the midrange opens up like an Orchid on a May day in San Francisco. Listening to Michael Kiwanuka's album "Love & Hate" is an absolute wonder. You realize what a talent Michael is. The Caldera and CFA3 perfectly render the somber mood, his cautious optimism, and political commentary. The song Love & Hate sounds so good I want to hit replay over and over. The CFA3 helps the Caldera open up, providing accurate ambience, perfect stage presence and the exact amount of air between instruments to evoke the full sensation of being in the studio as Polydor produced this amazing album. Bottom line, the CFA3 and Caldera are an absolute must hear. Top End Resolution is as good as I have heard.

Icon Audio HP8:
I was surprised how much I liked this combo. I felt the 60 ohm Caldera would prefer my SS amps. While the CFA3 is a study in Solid Stage perfection with the Caldera, the HP8 provides a beautiful, soulful, weighty, and powerful performance. Top end resolution isn't quite to the same standard, but the midrange and bass are hitting on all my preferences. I am using a pair of Sylvania 6SN7WGTA Brown Base 1955's and a RFT Rohre 12AT7 driver tube. A perfect compliment for the Caldera. Tonality and Timbral accents are slightly warm, and the music flows like a warm summer breeze. I keep using this sentence when describing the HP8 and it is borrowed from John Grandberg. But, the sensation is exactly how the HP8 sounds and the Caldera only further exemplifies why this pairing is worth a serious listen. They have phenomenal synergy.

Audio-GD R28 AIO:
This was the biggest surprise for me. The R28 is a wonderful balanced AIO. It has an R1 R2R DAC and a NFB-1 balanced headphone amp that is pushing 9.5 watts into 25 ohms and 8 watts into 40 ohms. More than enough power for the Caldera. The best part of the R28 is the R1 DAC inside. The sound is robust, weighty with just enough resolution to satisfy even the most discerning audiophile. I had about a 2 week period where the R28 was my favorite pairing with the Caldera. I love the sweetness of the vocal presentation, the physical nature of the bass, and the impeccable instrument placement. Especially with keys/piano and drummers. Listening to the Goose show from 1/15/2023 from Play Del Carmen with Bob Weir is a pure joy. Their new song Hungersite has phenomenal PRAT, and their reading of Peggy-O with Bob Weir is spectacular. Bob's voice sounds soulful, gentle and his ability to turn this Jerry tune into his own vocal experience is wonderful. Rick's voice counters with a more clean, young and reverberant experience. The R28 and Caldera are simply a special combination. I would say that a high end R2R DAC would be the best pairing for the Caldera.

Conclusion:
The Caldera is simply a phenomenal first planar by ZMF. It is powerful, subtle, emotional and technically adept. I cannot think of much that I would change, and that is rare for me. I have never given an audio product a 5 star rating, but the Caldera is worthy. The bass is deep and taut, the midrange is open and articulate, and the treble is sparkling without ever crossing over into sibilance. Pairings definitely change the headphone, and for those who like EQ, the Caldera takes very well to EQ. I, however, do not feel the Caldera needs EQ. I think ZMF nailed it and that is enough for me. There are a lot of options out there fighting for your hard earned dollars. You have several Planars that compete in the same price point, so what separates the Caldera? For me it is customer service, overall tonal balance, aesthetics, staging/imaging and a powerful sound. A most hearty recommendation.

​

ZMF Caldera Review: Thoughts After Two Months​

Opening​

A couple of months ago, ZMF’s new flagship, the Caldera, was launched. As per Zach’s explanation, Caldera is a pinnacle of accumulation of all the lessons Zach learned in his journey as a headphone developer: The Caldera incorporates a great deal of noble headphone design that is either new for this product (e.g., magnet structure) or proven in his previous works in moving-coil dynamic headphones (e.g., Atrium back damping system). Given how tastefully ZMF headphones performed to me, I don’t doubt that bodes well for the Caldera. However, with the highest price tag ever attached to a ZMF product, the new-born Caldera must prove itself in practice instead of riding on prior success. That brings us to this review where I’d like to discuss how much those advanced designs have added up based on my two months of intensive evaluations.

Disclaimers​

I’ve been a very enthusiastic ZMF owner for years (owned Eikon, Aeolus, Auteur, and Verite open; reviewed Atticus, Atrium, Auteur Classic, and Verite Closed) but I wanted a little high capability in terms of technicality as well as more neutral balance thus moved on. Then I entered a totl planar/ortho game a couple of years ago and settled down to the Stealth-Susvara swap.

Build / Aesthetics / Comfort​

I’d go brief about aesthetics, build, and comfort. I really don’t have much to say as Caldera shares a lot of design languages from other ZMF products. Excellent as usual ZMF. The same goes to comfort. The demo pair weighs 525g without cable in my scale. That’s more or less comparable to previous ZMF headphones. The weight was well distributed over the large surface and did not give me neck pain even with long listening sessions. It won’t be hard to find discussion about these points elsewhere.

Method and Associated Gears​

Below are gears I used in my Caldera evaluation

• DAC: SMSL M500 mk3 (usb in, xlr out), Gustard X18 (usb in, xlr out)
• Amp: SMSL HO200 (xlr in, 4 pin xlr out), Topping LA90 (xlr in, thorough banana-to-4p xlr adapter)
• Headphones: Hifiman Susvara, Dan Clark Audio Stealth

The demo pair of Caldera was made of American White Oak (stock wood). I also tried out lamb, suede, and cowhide perforated pads tailored for Caldera. I preferred and converged to suede pads eventually but my claims apply to any of these three pads I tested.

Caldera was mostly paired with M500.3 and HO200 for evaluation convenience -- easier to isolate headphone-specific effects from chain confounders and/or moderations. And because I didn’t focus on gear synergy much, readers should be aware that different pairings may draw different conclusions from my findings.

Subjective Analysis: Tonality​

While neutrality in tonal balance might be highly debatable and subject to various confounders, I’d confidently say Caldera has one of the most neutral tonal balances among the ZMF lineup both in perception and measurement. Let’s concentrate on the perception part in this section.

As usual for high end orthos, Candera’s bass extends down to the lowest register moderately. I might nitpick Caldera had mild attenuation in the lowest sub bass occasionally (e.g., audible with pipe organ tracks), which is alternatively perceived as a tiny hump around the upper subbass. It’s not a show stopper and likely attributable to my head’s sculpture rather than driver limitation because (1) I found the seal was very slightly broken behind the lobes and (2) bass extension was improved when I pushed both cups inward. So, how low Caldera can go must be a function of individual head shape, I believe. I also think that stronger clamping would result in better seal therefore better extension at a cost of sacrificing comfort a bit.

It is worth noting that other ZMFs I tested (Auteur Classic, Atrium, and Verite) have more audible roll-offs and stronger humps in higher frequency (100-120 hz). Caldera feels significantly more linear to me regarding bass responses.

Interestingly, compared to the energy level in mids and highs, I hear Caldera’s whole bass is gradually up-shelved, roughly by 3db or so. Put differently, Caldera’s bass sounds audibly warmer, which I believe makes Caldera sound more ZMF-ish.

While this differentiates Caldera’s bass from many other orthos (i.e., more ZMF-sounding) and I do appreciate it in many tracks, those coming from leaner orthos (myself included) may recognize it as being a bit too fat or thick. Fortunately, I found alternative ear pads or leaner-sounding amps could mitigate this to some extent.

Moving on to the midrange, I think Caldera leans toward the laid-back side. Its lower midrange is relatively recessed compared to its upper bass (as described above) and there's an even more energy cut around 1.5 kHz by a couple of decibels. This scoop is not as severe as that found in many HFM orthos including Susvara. I do prefer Caldera’s mids to Audeze LCD5/MM500’s forwarding presentation, too. But to my ears Caldera is not as spot-on neutral or full-bodied in midrange as DCA Stealth/Expanse, Seen HD6X0, or ZMF’s own Atrium.

The highs are surprisingly more present, refined and smooth than I typically expect for ZMF headphones. They maintain an appropriate energy level in presence as well as brilliance regions, and extend very well to the top octaves. I really like how crisply Caldera renders tenor sax overtones, female vocals, and hi-hats with good sparkles. While it took some learning curves (due to its elevated bass level), I found Caldera’s treble was more satisfying than LCD-5 which is mildly withdrawn, or Susvara which is a bit too sharp and edgy. It’s also easily the best ZMF treble I heard to date.

Subjective Analysis: Technicality​

Caldera is doubtlessly the most capable in technical prowess among all the products Zach has ever created. After two months of intensive listening, I am pretty confident to say Caldera is right up there and stacking well against any TOTL orthos money can buy today. Caldera surprises me in that it achieves an extremely high level of technicality without losing much ZMF-style presentation (which I believe somewhat conflicts with modern standards of high-fidelity).

When first putting on Caldera, the most immediate thing wowed me was soundstaging ability. Since Susvara joined my collection, it’s been very difficult to find headphones with acceptable soundstage in terms of both size and quality. Stealth was better in some areas (less distracting and more accurate spatial definitions) but slayed in the most areas that make headphones holographic. Caldera was the first pair of headphones that didn't make me feel relatively claustrophobic right after switching from Susvara: almost equally grandeur feeling, possibly better positioning for vocals and many core instruments, and great reproduction of characteristics of recording venues. I may nitpick Caldera is still more diffusing than Stealth and less airy/lively than Susvara. But none of those hurts enough for me to discredit Caldera’s holographic soundstages.

Caldera resolves tiny details (delta in frequency) and nuances (delta in amplitude) as superbly as any contemporary high end orthos costing 4k usd or more. Maybe a few ticks behind Susvara or Stealth on some occasions. But after carefully adjusting against perception tricks of tonal balance, it is nearly impossible to find out what specific components in tracks are unheard with Caldera over more revealing competitors. One may argue such a tiny difference is also caused by higher resolution and I don’t disagree. My point is they are pretty damn close in dealing with microstuffs. All the musical cues and information are equivalently resolved but presented differently across headphones.

Like many solid and matured high-end performers, Caldera’s weaknesses may be mostly a matter of gaps between personal preferences and intended voicing, rather than real performance issues. Nonetheless, I would like to point out a couple of Caldera’s behaviors where some buyers may feel disappointed.

I’ve recently seen an audiophile who found Caldera’s bass underwhelming. After listening to him explaining a bit more about why he heard that way, I realized people having a set of expectations about how orthos should sound used to look forward to hearing macrodynamics (dominantly characterized by tight, slamming, or hefty impacts) in certain ways. While I don’t think Caldera is shy of anything I listed, it’s also true that Caldera presents them with less squarer and less overshooting transients than contemporary high-end orthos. It’s possibly due to moderately damping on both sides with ZMF’s proprietary metal mesh and backwave damping system respectively. Or esoterically shaped magnets might play a role in air flow restrictions. These, confounded with thicker bass tonality, may not align with certain directions of expectation.

Also, I do think Caldera might not be the perfect replacement for other ZMFs like Atrium or Verite mainly because of timbre. While timbre might be an umbrella term for a set of multifactorial phenomena, I think one important factor in the technicality context is how sounding bodies excite mutl-order harmonics. ZMF’s prior drivers with biocellulose and Beryllium (vaporized) had their own respective harmonic excitation and Zach tastefully leveraged them to make reproductions sound more life-like, cohesive, and breathing -- which as a whole I often call ‘organic’. However, I don’t quite feel the same organic level with Caldera although it sounds more organic to me than any other orthos I experienced. Maybe Zach wanted to avoid making Caldera just an ortho-version Verite/Atrium or pursue different directions such as transparency (input signal fidelity) or less coloration. If so, I totally get it and it’s indeed one of the reasons I’d take Caldera over any other ZMFs for myself, but current ZMF lovers who want a full exclusive transition to Caldera should be aware of gains and losses before making irreversible decisions.

Subjective Analysis: Comparisons​

During my evaluation, I mostly compared them to the two TOTL orthos I had in the house: Hifiman Susvara and DCA Stealth. As I already made some comparisons in prior sections, I’d focus on noteworthy commons and differences.

Compared to HFM Susvara, I found:

• They both are excellent at emotional excitations.
• Caldera is thicker and richer but less delineated in bass. I often hear better details with Sus but notice finer volume gradation with Caldera in quiet but complicated passages. The difference is subtle for both aspects.
• Susvara’s midrange has been slightly ambiguous to me because of certain colorations and laid-backness (likely caused by acoustic designs such as cup interactions with minimal damping). Caldera’s midrange is also recessed due to different reasons but there’s not much evident ambiguity. As a result, vocals and main instruments are clearer and more articulate through Caldera.
• Soundstages are equally large and slightly diffusing on both. Instruments were separated more convincingly and understandably with Caldera. But Caldera is not able to reproduce as lively and open stages as Susvara.
• Overall, I like to pair Caldera with small ensembles, operas, and big band jazzes. Symphonies with large orchestrations are better enjoyed with Susvara. But they both have zero problem in switching genres I specified above. Needless to say, they’re also good at any other genres I didn’t refer to.

Compared to DCA Stealth, I found:

• Caldera isn’t as analytical as Stealth -- Caldera is more inviting and intimate in presentation while Stealth enables me to accurately and carefully capture sonic cues.
• Stealth’s complicated resonator array and overdamping enables almost zero coloration in both fundamentals and harmonics but introduces a sense of artificiality. Caldera opts out that route but is still well-controlled yet focusing on more entertaining, natural, and emotion-oriented sounding by comparison.
• Caldera is more holographic in soundstaging, exhibiting better lateral and depth sizes. Stealth is less diffusing and more accurate in layering and placements.
• Interestingly when I switch from Stealth to Caldera, everything sounds bigger and more organic. Reversely, switching from Caldera to Stealth feels like enhancing clarity and articulation.
• Stealth exposes me to the stream filled with overwhelming information and enforces me to maintain higher tension that leads me to relatively more fatiguing for longer listenings. Caldera let me take back, stay relaxed, still enjoy beautiful details.
• They both exhibit generally round and soft transients although Caldera sounds squarer between the two.

Notes on Amplifications​

I’m not chasing headphone amplification rabbit holes these days as much as I used to be. I still believe amps make differences.. But, beyond certain points, not proportional to the benefits I’d expect for the price deltas. I’m also a little disagreeing with general underpowering concerns when it comes to orthos/planars. I am rather concerned with overpowering cases because surplus current does more harm than good to me.

That being said, Caldera has not shown any hints of underpowering with moderate SS amps I hooked up with. Caldera required way less current than things like HE6 or Susvara. Hence, I believe Sonic synergies or flavor alignments should be prioritized in choosing amps for Caldera. I did try out a few exotic tube amps my friends had. Some sounded fairly impressive. But not enough listening to make bold claims. Anyway, I do recommend not to rule out Caldera solely because you don’t have monster-power amps.

Measurements​

My measurements were taken with the MiniDSP EARS at 95db SPL@300hz with the homebrew hybrid compensation target curve that mixed HPN, HEQ, and additional adjustments based on B&K Room Curve.

Please note that my frequency responses are averaged results based on 5 different positions (center/up/down/front/back) to control positional variance. Results from optimal positioning might differ even with the same measurement fixture/rig.

Highlights below:

• Slight sub-bass attenuation is attributable to suboptimal seals: I found the bottom of the pads was a bit loosely attached to EARS's silicon plate. As argued in the subjective analysis, I also had this issue with my real head although respective reasons for broken seals were different.
• The 4.5 kHz peak suggested by the graph is likely an artifact, too. It seems associated with internal resonance created by my ear coupler’s cylindrical ear canal, Caldera’s earcup geometry, or etc. Not very audible in the way it is presented.
• Slightly recessed region around 1.5 kHz is consistent with what I found in the tonality analysis. It looks like HFM scooping pattern but with a narrower bandwidth and less intensity. Fortunately, this relatively boosts 1 and 2 kHz separately to prevent too much loss in vocal clarity.
• Bass and lower midrange are slightly emphasized, which I believe is correlated with Caldera subjectively sounding closer to earlier (T50rp mod era) ZMF tone than more recent Verite or Atrium.
• The measurement confirms what I hear in highs: not overly bright but spot-on neutral.

I’m also attaching other measurements I took.

Conclusion​

While $3,500 is not a small sum of money for a single pair of headphones and there’s plenty of competition out there in cost-no-object orthos, Zach really surprised me with this fantastic debut product entering the summit-fi planar headphone market cluster. Surely in mostly good ways.

Caldera comes with a pack of great sound qualities (some being spectacular) that many other competitors with similar or higher price tags often fail to achieve: one of the two best treble responses I have heard through headphones, top-level soundstage and resolution excellence, and many many more. Of course this doesn’t mean Caldera is perfectly flawless. It’s actually not. There were some sounding behaviors such as midrange scoops that didn’t fully align with my preference. Nothing critical though.

All things considered, I can think of two clusters to recommend to shortlist or audition Caldera. One is the group of ZMF owners who want to add a solid technical performer to their collections. Caldera’s sheer detail-nuance retrievals and neutral tonality must be giving them a better chance to discover unheard sonic cues in many musics. The other is the group of hipster ortho buyers who pursue different sounding from mainstream high-end planars yet at the same performance level. As I claimed in this review, from technicality perspectives, Caldera does almost everything no worse than any other high end headphones I heard. And the presentation is drastically different from what I used to hear from orthos and rather close to ZMF moving-coil dynamic products.

Please let me know if you have any questions. Thanks for reading!

I’ll start as I usually do with sincere thanks to ZMF for allowing this amazing headphone to go out on loan. They were generous enough to allow a considerable amount of time in order to put it through it’s paces and I sincerely enjoyed my time with them. There’s a lot of info already out there about the Caldera's development and construction, I think it's worth reading & watching:

https://www.zmfheadphones.com/caldera-acoustic-design
https://www.zmfheadphones.com/measurements


Fit, Comfort and build

ZMF has a reputation for making headphones that are on the heavier side, and the Caldera is no exception (490 - 560 grams in current stock wood). IME ZMF also makes these headphones as comfortable as possible with their well padded headbands and suspension straps. Personally I've found that they never disappear on the head, but I've also never had an issue wearing ZMFs for hours at a time.

Like all ZMFs I've seen to date, the Caldera is simply beautiful for my tastes. The craftsmanship is impeccable, and the design is appealing. I'm always surprised how aesthetically pleasing I find each new ZMF release, but I probably shouldn't be. Zach and company have been at this for a while, and the quality of parts as well as the overall care in assembly is evident.
(Obligatory bad photo)


Review Details

Before I offer my listening impressions, I’ll start with a little about myself and other points of interest. I’m over 50 years old and have less than perfect hearing. I’ve been a music lover for as long as I can remember, and my preference leans toward the warm side of neutral. I’m a huge believer in the “my ears/your ears” axiom, and I believe the signal chain makes a difference. Feel free to liberally add as many mental IMOs and YMMVs as you want while reading.

My chain for playback is various WAV, FLAC, & MP3 files from my refurbed HP Elite Desk via USB to a Bifrost 2 to either my ifi Pro iCAN (1st version) or ZMF Pendant (also 1st version). The Caldera sounded wonderful from both the Pendant as well as the ifi, but I had a slight preference for the Pendant and did the majority of my listening utilizing that amp. No need to burn in during this go around since I have it on good authority that it has a couple of hundred hours on it already.

Sensitivity

For a planar the Caldera is fairly efficient with about 95db efficiency and 60 0hm impedance. As mentioned I only used my ifi Pro iCAN & Pendant which can drive them easily, but you can probably get decent results from many lower and mid tier priced rigs. I'd wager synergy will play a part here, but that is usually the case IME. If you're going to invest in a headphone of this caliber it makes sense to play it on a chain that'll maximize performance, but it's good to know that it's not a requirement for enjoyment.

Sound

When you hear the Caldera it is easy to hear the ZMF roots in the sound. I appreciate Zach's commitment to creating something unique with each headphone, which is evident when listening to the 1st fully in house designed ZMF planar. I only had one set of pads on hand which I can only assume were the stock lambskin pads, and I had no issues with them sound or comfort wise.

I think I understand why others have noted that the Caldera doesn't sound like a stereotypical planar. There is a recent trend (that seems to be thankfully changing) of utilizing the thinnest micro-nano-quark-sized diaphragm chasing the fastest transients and the lightest airiest sound. The stereotype speaks more to that trend than to planar technology itself. Obviously a planar can be tuned differently just as any driver out there. Hopefully the caldera will help to hasten the demise of this unwarranted bias.

Even though ZMF doesn't incorporate the thinnest most agile driver here, there is plenty of speed for my tastes. It is definitely faster than any beryllium drivers I've heard, but it's certainly not trying to sound like an electrostat. The flip side of that sonic coin is that there is a certain amount of heft & weight to the notes that you also wouldn't necessarily associate with the current crop of planars. Combined with the novel magnet structure and ADS (Atrium Dampening System, patent pending at the time of writing) the result is something fairly unique, which I believe was Zach's goal.

Bass

If you like the ZMF house sound I think there's a lot you'll like here. Being a planar, sub bass reaches low and it also has decent impact. More importantly there's texture and nuance to the bass; uprights don't sound electric, finger and pick plucking is audible, and electronic music is a joy.

Mid-bass is more subdued but is still full, rich and present. The emphasis is slight here, not bombastic, overblown nor bleeding into the mids. It's still a ZMF so probably more than many would describe as neutral, but Caldera sounds rather even throughout the spectrum to my ears.I found it easy to hear into busy passages, not just in the bass level, but I did notice it the most there.

Mids

The mids sound a bit more dry than I'd expect from a ZMF, but it's far from sterile or brittle. The slight recess around 1khz that others have mentioned didn't bother me in the least and wasn't particularly noticeable for me, unless that somehow contributed to the sense of dryness I noted. Either way vocals, both male and female, as well as all manner of brass & strings had plenty of detail and presence without edging into being perceived as shouty, shrill or overdone.

Treble

The treble is not your embellished over emphasized ear dagger by any means, however I found there to be more sparkle than I'm used to enjoying without fatigue. Despite this I has no issues listening to Caldera for hours on end without discomfort.There definitely could be a YMMV here given hearing loss. Also notably Caldera nails the timber of cymbals and such better than many other planars I've heard.

Detail

Detail retrial is quite good, I'd say among the best I've heard. It's not what I sometimes call hyper-revealing where the presentation is all about magnifying details, but I found plenty of sonic information when I listened for it. I found that if I did concentrate I could isolate many hidden gems in the music, but more often than not I found myself getting lost in the song itself. I think detail is important when it's lacking but at a certain point that emphasis can be distracting for me. Caldera straddles that line without ever crossing over.

Compared to Atrium

I don't have a planar on hand that would be a good comparison here (just the HiFiMan 400i & a memory of some time spent with the D8000 - not the pro) so I figured the Atrium would be a good side by side despite the drivers being different tech. Note I'm using the stock Universe pads with the Atrium & the solid mesh (I'll have to try the perforated mesh one day since many people I know that have heard both seem to prefer it).

Comfort

Despite being about the same weight (cherry Atrium is also supposed to be 490g), I found the Atrium to feel a bit lighter. IDK if it's because of clamp or weight distribution, but it was noticeable for me. Keep in mind I had no comfort issues with Caldera, but it's worth noting.

Bass

Caldera bass definitely reaches lower with a more even mid-bass, and the Atrium has a more pronounced mid-bass accentuation. Atrium sub-bass does roll off yet it is still audible if not as forceful. Caldera is tighter, Atrium looser though no where near flabby or indistinct. Atrium definitely slams harder though Caldera is no slouch.

Mids

Caldera mids are slightly dry and Atrium comes off as more lush yet both presentations I found extremely engaging. Caldera had a bit more lower mid presence and the Atrium a slight push in the upper mids in comparison. Neither sound too forward nor too recessed to my ears, though my mids preference seems to lean toward the Atrium overall. I'll note here that overall I found the Atrium to be more forgiving of sub-par recordings, and the mids may have a bit to do with that I think.

Treble

As mentioned treble is indeed not my strong suit, but from what I can hear Caldera is less rolled off and more even and airy up top. IDK if it's related to the treble but I found that Caldera was more resolving overall in comparison to the Atrium though not by a huge margin. Detail was easier to discern, and I found that especially so in the treble region.

Headstage

Headstage is wide deep & coherent. The Atrium bests it to my ears, but Caldera definitely has a great sense of width & definitely depth. Height isn't lacking, I just didn't find it to be on par with with the other axes, and I didn't find it to be distracting. There is still a great sense of space and "realness" that I don't often find with other headphones. Both headphones draw me in like few others I've heard, and though the Atrium does seem to have an advantage I wasn't turned off by the Caldera staging at all.

End Words

After comparing the two I'm not sure I could pick one over the other, both the Atrium & Caldera are an absolute pleasure to listen to for my tastes. When going back & forth comparing songs I found myself having a slight preference, but it was never for the same headphone. I always enjoyed what each headphone brought to the table, and it was always track dependent. If I didn't already own the Atrium I could definitely see myself saving for a Caldera since the sub bass reach and overall detail appeal to me. Owning the Atrium already I don't feel I'm missing anything, and the Atrium's strengths align well with my preferences. If I had the money, I would more than likely have them both in my stable. IMO Caldera is definitely worthy of it's co-flagship status and is worth checking out.

I always look forward to new headphones from the gang at ZMF. I was in the market for a new pair of planar magnetics and I asked Zach for a recommendation. Seeing as he started with modded T50's, I assumed he had probably heard most planars out there. I own two pairs of ZMF's, a pair of Cocobolo Eikons and a Walnut Burl Aeolus so I am reasonably familiar with the ZMF house sound and I trust Zach's opinion. Instead of recommending a one of the the headphones I had asked him about (Hifiman Arya or Audeze lcd X), he mentioned that he was developing his own High End Planar Magnetic headphone, and that he would be willing to let me try them out if I was willing to wait. I was, indeed, willing wait and a month or so ago a pair of ZMF Calderas showed up on my doorstep. Thank you Zach for the chance to try these out.




I have been listening to the Calderas for the last month connected to both tube (Cayin HA-3A, with Baldwin/Sylvania 12au7's and matched NOS 6V6GT Westinghouse tubes) and solid state (Audio-gd NFB-1) amps. Each connected balanced to Geshelli J2 DAC's via Blue Jeans Cables XLR cables. I also used only the balanced outputs on both amps.




While Zach made it clear that no review was necessary, I thought I would post my impressions anyhow.

Build quality and comfort – Long a hallmark of ZMF, the build on my Calderas is immaculate, no creaks, no loose nuts or bolts, nothing to indicate that these are hand assembled. By any visual measure, these are perfect. It is no lass than I have come to expect from ZMF, but I marvel each time I pick them up at how solid and sturdy they feel without feeling simultaneously heavy and awkward. The pads are soft and deep and my admittedly large ears fit comfortably with with only the bottom of my earlobes touching the bottom of the cups.

The new comfort strap and padded headband are a noticeable improvement over the previous stock headstrap while the rest of the hardware is reassuringly solid and allows for easy adjustment without fear of slippage.

One last note regarding the physical build. The slightly concave mesh grill on the Calderas is beautifully machined and sits perfectly flush with the wood. The concavity is, I assume either a function of the new drivers, or a nod to the name Caldera. Either way, the cups are approximately the same size as the Aeolus, and by definition smaller than my Eikons. The grill also lacks any visible mounting screws, which lends itself to a cleaner overall aesthetic than the Aeolus. I will have to note, for the record, that from a purely visual standpoint, I prefer the grill and wood of the Aeolus, with is marvelous gleam texture. The Caldera also sports 2 and a half pressure release vents around the grille. This is in contrast to the 5 full vents on my Eikons. As the Eikons are closed back, I assume these are necessary to relieve the pressure while the Calderas are open-ish and need less venting. I say open-ish because less sound escapes these than the Aeolus or, for example, the very open Dan Claek Audio Ether 2’s. The majority of my headphones are closed back so I have little frame of reference when it comes to open back units.

Finally, the sound. The ZMF Calderas are the best sounding headphones I have ever had the pleasure of listening to for an extended period of time. Their defining characteristic is how utterly engaging they are. The sound is full, lush and fast. Whether connected to a tube or solid state amp, the Calderas just make me want to close my eyes, smile, and enjoy my music. The sound is relaxed without being muffled in any way. On Stevie Ray Vaughn’s Mary Had A Little Lamb (Live Alive, 1986), Stevie Ray’s frenetic guitar playing floats seamlessly above Reese Wynans’ keyboard riffs. Both easily distinguishable from one another without losing any of their individual power.

Again, instrument placement and definition is excellent, to whit, Miles Davis’ Duran (Take 4) (The Complete Jack Johnson Sessions, 2005). The interplay between Davis and John McLaughlin and their relative placement in the virtual space really give the impression of two wily fighters sizing each other up. The instrument clarity is sublime while both the lows of McLaughlin’s guitar and the high’s of Davis’ horn manage to stretch the soundstage to it’s breaking point.

Female vocals are also handled with aplomb. Natalie Merchant’s San Andreas Fault (Tigerlily, 1985) is rendered silkily. Her voice, strong and smooth is conveyed flawlessly above the delicate keyboard backing track. No sibilance whatsoever.

Lastly, a bit of Electronic to round out the listening impressions and see how the Calderas convey bass. AtomHD’s I Love U (Like I Love My Drum Machine) (HD, 2013) brings the low end forcefully, making you feel like your eardrums are the synthesized drum skins.

All of this is to say that the ZMF Caldera is an exceptionally well rounded headphone. Base, mids, and treble are all handled masterfully and the overall experience is one of complete immersion in the music, regardless of genre. These are the most engaging and enjoyable headphones I have ever heard and I heartily recommend them to anyone looking for an end game headphone that will last for years and never lose it’s charm.

I have now had the Caldera in my hands for a week and, while it is obviously too short a time for a serious review, I am sharing my first impressions knowing that many community members are eager to learn more about the Caldera in advance of its upcoming launch.



TLDR

The most resolving ZMF to date, the Caldera offers a densely textured timbre with a palpable “weight” behind the notes. Most notably, it has an excellent bass, the kind that moves you both physically and emotionally, without being artificially elevated. ZMF signature mids. And a lower treble energy, in line with ZMF warmer tuning. The Caldera is energetic, snappy, and exciting. Overall presentation is more intimate and forward. It commands your attention.

The Caldera is extremely engaging and enjoyable. Every time I thought of taking some notes I blinked, and 3-4 hours passed by as I got lost in the music. There are a couple of more resolving (and expensive) headphones out there, but the Caldera’s presentation is entirely unique. It is engaging and tactile. Once you put it on, it refuses to come off.

In advance of my impressions, I am sharing some detailed notes below about my chain and personal reference points, as well as some notes on packaging, build and comfort. Skip down to “SOUND!” if you want to get to it, or to the “COMAPRISONS” or “CONCLUSION” further below for an even shorter read

BACKGROUND NOTES

My Tastes
I have an eclectic collection of music across most genres. I gravitate more toward acoustic and vocals in general, but I will mix jazz, classical, rap, rock, blues, R&B, and anything else that simply moves me.

My current favorite headphones are the ZMF Atrium, Audio-Technica ATH-L5000 (with ZMF Universe Lambskin solid pads), Hifiman Susvara, and Stax SR-X9000.

Chain Used
Roon Nucleus+ ➤ CAT 7a ➤ Audioquest Cinnamon RJ/E ➤ Bricasti M3h (power cable: Audio Sensibility Testament SE) ➤ Moon Black Dragon (XLR) ➤ Zynsonix custom switchbox (silver cabled) ➤ [1] Moon Black Dragon (XLR) ➤ Auris Nirvana (power cable: Nordost Heimdall 2) , [2] Kimber Kable Carbon Interconnect (XLR) ➤ Simaudio MOON 300A (power cable: Audio Sensibility Testament SE) | power conditioner: IsoTek EVO3 Aquarius

At Zach’s suggestion, I am listening to the Caldera with ZMF’s silver cable.

3 Caveats
(1) I have only had the Caldara with me for a week. Including two weekends, I’ve logged approx. 50 hours of listening time. My impressions may, and likely, will change further.

(2) I am not a professional reviewer. My knowledge and experience are limited to that of a deeply passionate consumer. I am a community member who enjoys headphones, and I am deeply passionate about discovering and listening to great music. If it sounds good to me, I like it. If it doesn’t, I don’t. Sometimes I can explain why. Sometimes I know why. Often, neither it true I will do my best to explain myself and offer examples wherever I can.

(3) I am typing this review in a single sitting. The NYC Marathon passes today a block away from our place, giving me the perfect excuse to stay home on this unusually warm and beautiful November day and to commit to this promised writeup. I may come back here later once or twice to fix a typo or correct any small error or omission I may have missed in this writing sprint.

Reference Headphones
When listening to the Caldera, I have mostly used the following headphones for comparative reference:

• ZMF Atrium (ZMF Letrik S cable)
• Hifiman Susvara (Linx Diamond silver cable)

I have made select comparisons to these headphones in various sections below to help draw contrasts and highlight Caldera’s unique presentation characteristics. I have also referenced one or more additional headphones. In my summary comparison notes, I have also included the Vérité Open.

Reference Tracks
I have drawn my impressions from tracks I am very familiar with that span a wide variety of genres. I included links to all the referenced tracks.

FIRST IMPRESSIONS

Packaging
The Caldera I received is the Kingwood LTD, which comes packaged in a beautiful wood crate. The unboxing experience is the usual ZMF affair, with great attention to detail and, as always, feels very premium.

Build
I am referencing the Caldera Special Kingwood LTD. Per Zach, these will be offered at launch as a limited edition alongside the oak and golden coffee stock models. The Kingwood are a stunningly beautiful, glossy, darker wood (a hint of reddish hue is seen under direct light and in photography; in real life, they are a more of a dark brown rich wood color).

The build is ZMF exceptional. Wood, leather, magnesium chassis. It’s a joy to hold in your hands. It feels what it looks.

The Caldera are identical in their excellent build and comfort to all other ZMF headphones. They feel perhaps a touch heavier than other equal weight ZMF headphones (my 609g Caldera feels similar to my 624g VO blackwood). I am guessing that the weight distribution has changed a little as a result of the driver magnet weight and the new pad design. After a week, I wear them happily and comfortably. But, if you are sensitive to weight, consider the stock models, which I believe Zach indicated will be running around the 500-550g range.

Pads
The Caldera’s new pads, per Zach, will be called (wait for it..) “Caldera” They are made of leather (lambskin?) which feels great. I have always loved ZMF leather pads. The Caldera pads seem to have a bit less surface area on my face compared to the Universe pads. They do however offer an excellent seal. Two additional pads will be available, including suede and cowhide. They will undoubtedly change both sound and comfort, but I have not had a chance to test them yet.

SOUND!
The Caldera shares the Atrium’s damping system, and they are both unmistakably ZMF-tuned headphones. But they do sound rather different from each other. Where the Atrium’s slow attack and beautiful decay offer a lush and organic presentation, the Caldera is distinctly faster and snappier (it actually reminds me much more of the VO in that regard). The Caldera mids are also more forward relative to the Atrium. The Caldera’s sound signature is definitely not relaxed... but I have certainly found myself relaxing and getting lost in the music.

Bass
The Caldera’s most distinct feature for me is its amazing bass. It may be my favorite, across all headphones. ZMF’s first planar offers a clear distinction here compared to its dynamic brethren, but it also stands apart from other planar headphones. The Caldera bass extends low. It is deep, textured, and physical. It moves you, figuratively and literally. It is not one of those cases where it is a “headphone feature”, like the Abyss 1266. It is neither exaggerated nor elevated. Bass quantity depends on what the recording calls for. Opinions about the Susvara’s bass differ, but I love the Susvara’s bass as voiced through my power amp. In comparison, the Susvara’s bass is a bit more “open” and effortless, while the Caldera’s bass is “denser” and physical. This distinction is generally representative of their respective voicing, which are distinctively different.

Caldera’s lower bass region is magical. This is notable in acoustic music. For example, in the deep and richly textured bowing of the double bass on “Blind-Hearted” by Sarak K. (Water Falls - https://open.qobuz.com/track/87979534), or in the beautiful classical rendition of Valenyn Sylvestrov’s “Wedding Waltz” performed by Hélène Grimaud/Camerata Salzburg (The Messenger, Extended Edition - https://open.qobuz.com/track/126195369) where the occasional vibrato of the double bass and the lower piano register notes are beautifully resolved. I particularly like the rich plucking of the double bass on jazz tracks, such as on Ron Carter and Houston Preston’s duo “Love Is Here to Stay” (Remember Love - https://open.qobuz.com/track/51156776).

For those who enjoy the planar slam of drums, the Caldera has it, in spades. For example, the fast attack of drums on Michael McDonald’s cover of “I Heard it Through the Grapevine” (Motown - https://open.qobuz.com/track/13650307) offers a very satisfyingly, crisp articulation; and the hard-to-resolve bass guitar in Boz Scaggs’s “Desire” (Dig - https://open.qobuz.com/track/96893171) rumbles beautifully.

Sub-bass
The Caldera’s sub-bass doesn’t extend as low as the Susvara’s, but it is a little bit more forward and physical. For example, on tracks such as “Blinding Lights” by The Weeknd (After Hours - https://tidal.com/browse/track/134858702) or “New Oldie” by Snoop Dogg/Usher/Eric Bellinger (Snoop Dogg Presents The Algorithm - https://open.qobuz.com/track/138711392) I felt the satisfying feeling of a subwoofer shaking my core. For those who enjoy that, you are in for a treat.

Relative to each other, the Caldera provides a more hard-hitting bass and sub-bass, while the Susvara provides a more neutral presentation and a lower extension. However, the more poignant comparison here would be between the Calendar and Atrium. The Atrium will highlight more the mid bass as its lower bass will naturally rolls off, while the Caldera will draw your attention to the lower bass register, extending deep into sub-bass with a more forward and linear presentation.

Mids
This is a ZMF, through and through. The Caldera’s unique trick is bridging the natural timbre that is normally associated with dynamic headphones with the speed and bass extension of planar headphones (perhaps it is the combination of its planar magnetic drivers with the Atrium damping system. I am sure there is much more to it, including pad design and a very painstaking driver tuning process).

I am a sucker for vocals. It is the main reason I have had several ZMF headphones. However, the Caldera and Atrium do sound different here. The Atrium voices female vocals softer and rounder. It is a sweet and caressing, velvety tone, the kind that wills you to close your eyes, lean back, exhale and lose yourself in the music. The Caldera “opens up” the sound with a more crisply resolving, clear, and forward presentation. It asks you to lean in, grabbing your attention.

When listening to Sabina Sciubba & Antonio Forcione’s vocal/guitar duo cover of “Estate” (Meet Me In London - https://open.qobuz.com/track/59943654), the Caldera separates the vocals and guitars with great clarity, while the Atrium soften the notes. The guitar plucking is better resolved on the Caldera. On the other hand, on Samara Joy’s cover of “Stardust” (Samara Joy - https://open.qobuz.com/track/151697608) I prefer the softer and more rounded presentation of the Atrium.

Compared to the Susvara’s more ethereal presentation of the mids, the Caldera’s mids are more densely textured and weighty. They are both beautifully and exquisitely resolved.

Treble
The Caldera is tuned a touch warmer than neutral and there is certainly less presence in the treble region. This may be welcome by those who are treble sensitive, and in this regard, it is similar to the typical ZMF tuning with a gentle treble roll-off. I noted that with its reduced treble energy, it is also less resolving in the treble region than the Susvara. For example, in Michael Frank’s “Now that the summer’s here” (Time Together - https://open.qobuz.com/track/121160413), the hi-hats and maracas are more clearly resolved and more distinctly layered on the Susvara which extends more linearly into the higher frequencies.

Soundstage
This is where I find the Atrium shines and has a distinct advantage over the Caldera. There is something special about the Atrium’s staging, a certain holographic presentation that surrounds you, which is entirely unique. The Caldera’s soundstage is done well but feels more traditional 2D (horizontal left to right).

For example, on a live track at a small jazz club, such as in Sheila Jordan’s rendition of “Comes Love” (Winter Sunshine - https://open.qobuz.com/track/168305625), the Atrium gives a sense of sitting inside that small jazz club in Montreal, surrounded by the soft echoes of the brick walls around. The Caldera here sounds great on this recording but presents the stage more like a perfectly mastered studio recording than a reflection of that live club setting.

In recordings from big wide venues, the Atrium offers a wider stage, whereas the Caldera is narrower in comparison. For example, in Eric Clapton’s live recording of “Wonderful Tonight” (Forever Man, Deluxe Edition - https://open.qobuz.com/track/23361774) or Sara Bareillles cover of “Goodbye Yellow Brick Road (live)” (Brave Enough: Live at the Variety Playhouse” - https://i.imgur.com/fGFaGiK.png) the Atrium’s presentation is placing you closer to the front of the stage with the sound surrounding you and dissipating around and behind you, while the Caldera puts you further back in the concert venue, perceiving the sounds coming from the stage in a narrower dispersion which would reflect such a perspective.

In the Oscar Motet Choir’s famous 1976 recording made inside the Oscarskyrkan church in Stockholm, listening to “Hossiana, Davids Son” (Cantate Domino - https://open.qobuz.com/track/4410172), the Atrium captures the height of the church, whereas the Caldera presents a more focused soundstage.

Imaging
While the Atrium provides more spatial cues within the soundstage, the Caldera’s speed results in much clearer and superior instrument separation.

On “Wild Women Don’t Have The Blues” by Cécile McLorin Salvant (Dreams and Daggers - https://open.qobuz.com/track/43459125), the Caldera offers a much better separation between Cécile’s vocals, piano, bass, and drums; at the same time, the Atrium creates a better image where in the space these instruments are positioned.

Resolution
Caldera is, notably, the best resolving ZMF headphone. It can also handle complex tracks with ease. I have benchmarked it against the highest resolving headphone I have on hand, the Stax SR-9000X, and I was surprised to see how well it has held its own. With the exception of treble frequencies (see above) where its detail is more recessed, the Caldera is otherwise a resolution monster. It almost matches the X9K resolution in the mids and is superior to the X9K in the bass(!). That is quite a fit. On a complex track such as Yoko Kanno’s “Tank!” (Cowboy Bebop - https://open.qobuz.com/track/96723118), the Caldera effortlessly renders the details, making for an incredibly enjoyable listening.

Amplification
Regarding how the Caldera is impacted by, and scales with, amplification, I can only offer very limited insight at this point. This requires much more listening time, as well as more gear than I currently have on hand. But I can offer the following anecdotes:

My Caldera listening was almost exclusively done on the Auris Nirvana, a powerful (6.5W) transformer-coupled tube amp characterized by very clean and linear power amplification (for those interested, currently rolled in are a 1974 Siemens 5814A drive tube, and two Sophia Electric EL34-ST power tubes). This has been my daily driver for all ZMF headphones, and the synergy with the new Caldera has been excellent.

I tried briefly two other options.

First, I tried using the solid state amp built into the Bricasti M3h (I otherwise use it purely as a DAC). It is not overly powerful. Based on a couple of available data points, I am guessing (very crudely) that it provides about 0.5W into 60 ohm, so not exceptional headroom. The amp is quiet and proficient. It drove the Caldera easily and well. Switching back to the Nirvana, I felt the expected richer tonality and weight on the notes, but this was not a massive change. The Caldera is not an exceptionally power hungry planar headphone. But it will benefit from improved amplification.

Which gets me to the juicy second anecdote.

I couldn’t resist the temptation of trying the Caldera on the power amp setup I use with the Susvara, plugged into my Moon 330A speaker outs (125W into 8 ohm, SNR 100dB at full power) with volume control through the Bricasti’s pre-amp. My experience to date on this specific chain has been that only my Susvara (83 dB) and Arya V2 (90 dB) were insensitive enough to work well in this chain, and with all planars in the high 90s and up, the noise floor became audible. At 95dB, the Caldera offered an edge case. I found that the Caldera soared! Soundstage expanded significantly, and the overall presentation became more dramatic and exciting than it already was. Yet, it is still borderline. When the music is paused, the noise floor is just, slightly, audible. It disappears with the music, but it is enough for me to likely continue using the Nirvana as my daily driver. But I suspect that much of the lore of Susvara owners, filtered through a different sensitivity lense with a much greater emphasis on exceptionally low noise floor, can lead to some interesting discoveries and exciting possible synergies. Entirely anecdotal and speculative.

COMPARISONS

Reminder, for those who have jumped down here skipping all the detailed notes above. These are first impressions only. With that, let’s get to it…

Caldera vs. Atrium
This question seems to be highest on everyone’s mind. Two new ZMF flagship headphones this year, one dynamic and one planar. If I already have one, should I get the other? If I have neither, which one should I get?

I wish I had the simple answer you are looking for, but I can only offer an “it depends”. Personally, I will definitely be keeping both as they are highly complementary and really quite different in their presentation.

The Caldera is more resolving (but when I listen to the Atrium on its own, I do not feel like I am missing any detail). The Caldera also extends better into the lower bass and sub-bass frequencies, where it is more visceral and outright physical. The Caldera is also a faster headphone, resulting in a much faster attack. For example, on Counting Crow’s cover of “Big Yellow Taxi” (Hard Candy - https://open.qobuz.com/track/61540069), the slam of drums is much crisper and more exciting than on the Atrium’s. And Terri Lyne Carrington’s quick drum beats on “Come Sunday” (The Mosaic Project: love and Soul - https://open.qobuz.com/track/54351500) are rendered with better speed and clarity.

If there were a single word to describe the Caldera, it would be “Exciting”.

The Atrium, in kind, offers a much more unique soundstage presentation. The slower Atrium offers an incredibly organic and lush sounding decay. Both of which can be heard on Aaron Copland’s famous “Fanfare for the Common Man” (Copland 100, Minnesota Orchestra - https://open.qobuz.com/track/5164109). On this track, the horns’ blast echo in the wide concert hall, and the low bass beat of the drum decays beautifully and naturally, giving a sensation of being present in the venue unlike any other headphone I know.

On “Deadwood” by Tony Braxton (Sex & Cigarettes - https://open.qobuz.com/track/47776201), each of these headphones highlights different strengths: the Atrium presents the lush decay from the bass, making the sound feel organic. While the Caldera’s voicing of the drums is crisper, with a clearer separation and a better layering of vocals and instruments.

If there were a single word to describe the Atrium, it would be “Analog”.

Put differently, the Atrium offers a more relaxed, lean back, lush sounding voicing. While the Caldera commands your attention, presenting you with highly resolved detail, speed, and physicality.

Caldera vs. Susvara
This seems to be the second most popular question at present. How will ZMF’s first planar fare in the uber competitive top-tier planar market? In specific, how would it compare against the Susvara?

The simple answer here is that these headphones are so far apart in voicing, it is almost an academic question. Except in technicalities, the Caldera is much closer in its presentation to its dynamic siblings than to other planars. Given they were tuned by the same ear, it makes sense.

Comparatively, the Caldera offers a warmer tuning, and its voicing sounds thicker and fuller, lending an extra weight to the notes. In contract, the Susvara offers its famous ethereal light touch and effortless resolution. The Susvara’s overall resolution still reigns, and it offers soundstage and imaging that (from the headphones I have experienced) can only be rivaled by the X9000K (note that both of these headphones retail at nearly double the Caldera’s price). However, if you like ZMF’s presentation of vocals and mids, you will likely gravitate to the Caldera.

These headphones simply offer a very different presentation.

It is a choice between the most dynamic-sounding planar vs. the most electrostatic-sounding planar.

Caldera vs. Vérité Open
This was somewhat surprising to me and a little counterintuitive, but I found the VO closer in its presentation to the Caldera than to the Atrium.

Where the VO is a bit more aggressive and faster than the Atrium, the Caldera is even more so. While I plan to keep both, I can see some folks viewing the Caldera as a possible upgrade path from the VO, especially those listening to more energetic music. In genres such as hip-hop/rap or rock, the physicality, bass extension, and planar speed of the Caldera may prove to be winning attributes.

However, if you have vocals and acoustics in high rotation in your listening, the VO may offer an edge in this comparison, providing the beautiful and more natural timbre of the ZMF dynamic sound, while still keeping you very satisfied with its bass and aggressive attack.

The Caldera’s resolution is superior (to that of all other ZMF headphones), while the VO’s timbre is a bit more organic. Both ways, I am close to splitting hairs.

For example, on Haley Reinhard & Jeff Goldblum enjoyable rendition of “My Baby Just Cares For Me” (The Capitol Studio Sessions - https://open.qobuz.com/track/131263909), I prefer the VO’s vocal presentation, and find the spatial cues to be more natural, while the Caldera offers better instrument separation and a more mid forward presentation.

If I were to keep only a single ZMF headphone, it would probably be the VO, as it offers a perfect middle point between the classic ZMF organic timbre, and the attack and speed of the Caldera.

If I could keep two, I would take the best of both worlds, which for me are the Atrium and Caldera.

Either way, you can’t go wrong!

CONCLUSION

If you paid attention earlier and noted that I have logged 50 hours of listening time on the Caldera in a week (including 2 weekends, to be fair) and have done some mental math, you may have realized that the Caldera have been on my head for pretty much most of my waking hours this past week. This wasn’t for the purpose of this writeup (to which I committed solely this beautiful Sunday), but entirely for my personal pleasure. The Caldera is just one of those extraordinarily enjoyable headphones that once you put them on and start the music, you realize that bedtime was a few hours ago…

The Caldera is a really unique headphone. It shares the beloved ZMF sound signature, warm tuning, and beautiful mids. To that, it adds excellent speed and resolution, and a truly exciting, well extended, visceral bass.

I suspect that, in the long run, the Caldera will gain a massive following. Count me as one of its very first…

…and now, please let me get back to the music