Audeze CRBN

Background

I’ve been following the Audeze journey since their inception back in 2009, as a primarily planar magnetic company the CRBN was quite a departure from their usual tech. I won’t go into specs and even the background of their carbon nanotube film drivers since that has been covered heavily elsewhere.

I’m also late to the party as the CRBN2 has been announced at the time of writing this! but i wanted to write about the original CRBN as I have had the pleasure of spending the past year with it, trying it with various amps and have compared to quite a lot of other relevant stats.



Build:

Great built quality, especially so vs nearly all other electrostats on the market. The marbled graphite cups exude class, whilst the overall quality feels a step up from the usual LCD range, and better than most other electrostats including TOTL ones. The overall design is well done, I especially like the tesseract style grille pattern.



General Sound

CRBN is very different in sound to most major brand electrostats out there. This is probably partly due to the design, with a combination of felt driver damping (Stax has none), highly sealing earpads and the rear grille design.

This results in a large departure from the typical Stax sound (ethereal, ultra open, wide, trebles which are very extended but can get a little spicy at times ) to a much more full-bodied sound. The sound also slightly tapers off at the upper and lower frequencies extremes.


Bass quality superb, full of texture and detail and warmth, which is not always there in an electrostat, but a hint below where I like it in amplitude(I am kind of a bass head!).

Mids are super clear with body, I find the timbre on this much more natural than most Stax (Lambdas etc) I feel a sense of listening to the ‘real’ much more than with most Stax. Upper mids have a slight elevation, which adds some presence but might be a touch overemphasized for some tastes.

Treble is smooth and non-fatiguing, which is a blessing for those (like me) sensitive to sharp highs. However, there’s a slight roll-off in the upper treble, which reduces the sense of air and openness.
Soundstage is medium to small, but what it lacks in size it makes up for in 3-dimensionality and textural layering, which are a step above most stats other than the very TOTL.
Overall it beats most stats for me, and whilst having a different signature, is on the level of the TOTL stats for comparison (SR-007, X9000 etc. More on this later).


I now use it with EQ, basically based on Bob Katz eq (google it) slightly modified. To give it that extra bass and then I end up spending way too long into the night enjoying music.


Amps

Audeze recommends a very strong amplifier, and I now realise why. These are less sensitive than even the difficult to drive SR-007. Additionally these are more amp sensitive than any other stat headphone I’ve heard so far. With weaker solid state amplifiers they will sound a bit dulled. With most powerful solid state amps (e.g. KGSSHV) it becomes a little bit hard in the upper mids and just overall.

Once you go to a reasonable tube amplifier, they suddenly transform, quite dramatically into a world class headphone. I have had good results with SRM-T1, 006t, 007t/A, BHSE, T2, Viva Belva, ifi Phantom. Tube amps that weren’t my taste (a bit too lean and made the elvated upper mids too prominent) were LTA Z10e, Viva STX, and to a lesser extent KGST.

To me the CRBN comes most alive with tubes. The exception being the Mjolnir Carbon CC, which is a tubey sounding solid state amp. To me it paired best with the BHSE or Mjolnir Carbon CC. Both endgame level pairings IMO.



Headphone comparisons

Quick comparisons, CRBN vs;

Stax SR-X9000: Compared on BHSE and Viva STX. The X9000 offers greater openness, soundstage width, and extension at both frequency extremes. It has a slight diffusion and upper mids recession (vs the CRBN slight elevation). However, the CRBN delivers better body, timbre, and 3D stage imaging, making both equally compelling and enjoyable performance wise from the BHSE.


Stax SR-009S: the 009S is also slightly rolled off on the extremes, but unlike the CRBN, the 009S sounds a bit dead. It sounds more open but I prefer the CRBN in nearly all aspects

Sennheiser HE90: The HE90 sounds incredibly open, smooth and has more apparent extension. The CRBN upper mids elevation is evident in comparison and the less open nature makes it lose out here. Actual overall performance isn’t actually too far apart. But the HE90 just has all the boxes ticked and does everything so well it wins.


Sennheiser HE60: HE60 is hard sounding, trebles too harsh , both compared on a Kerry T2. CRBN sounds much more natural and smooth, much more musically engaging. I understand many may disagree, but this is how I felt.

Hifiman Shangri-La Sr: Compared on Viva STX (which is a bright amp) the Shang Sr was unlistenably bright, completely lacked bass and body. Even compensating for the amp, the CRBN, whilst not sounding ideal on this amp, sounded much better, much more even and neutral, better body, bass, smoothness, etc. CRBN only lost out on resolution, and that is probably due to the excess treble in the Shang Sr.


There are many more, but basically it wins out vs pretty much all non TOTL stats here.


Closing comments

The CRBN is not perfect. But it is a beautiful headphone to listen to music and let it disappear (once you have the right amp and EQ the bass up a bit). It very quickly made it difficult for me to listen to nearly all of my other headphone and electrostats. Is it the best sounding headphone in the world? No, to me that title belongs to the Sennheiser HE-1 (unfair), but is it a great headphone in the TOTL leagues? Yes very much so, one of the best stats made. And with a very different flavour to the other stats and totl out there. Certainly much better than the middle range stats out there, and a matter of taste in the high end stats world.

With slight bass EQ I love it. If it had extra bass and a bit more air. Then it would be killer. Interestingly this is what the CRBN2 teases, hence the future is very exciting!

Introduction​

Today we are taking a look at a very interesting headphone from Audeze. Now, the immediate assumption is that if a headphone is an Audeze, it’s a Planar Magnetic. In this case, however, The CRBN is an electrostatic pair of headphones, Audezes first foray into this product category. The CRBN, and more specifically their driver technology, is slightly different from traditional electrostatic headphones and is derived from a driver that Audeze made for use in MRI machines. This meant that no metal could be used within the driver’s makeup. Audeze has instead used carbon nanotubes throughout the driver (to provide conductivity as far as I understand) and as such, this is where the name CRBN comes from. Overall, whilst it’s a very neat concept, I’m more concerned about how an individual pair of headphones sounds, vs. being worried about the technologies used to create it. With that being said, I give Audeze a ton of credit for continuing to try and improve and innovate, and coming up with creative solutions for headphones.

Past History vs. Now​

Now, I have a bit of a history with the CRBN itself. Both positive and negative. I’d recommend reading through the entire review, as the CRBN has seen a change over its lifetime, and this directly impacted my overall opinions about the product. I originally purchased a pair of CRBN a few months after their initial release, and they were delivered a few months later. That first pair was entirely broken, but no worries, headphones.com swapped it out for another unit they had in stock, which was great. This pair was entirely functional and what was to be expected from a CRBN at that point in time. The problem was that…..it wasn’t really usable in an overall sense, at least not easily or as you would expect, even from a typical electrostatic headphone. Audeze made a statement that the drivers were tensioned slightly more loosely than other electrostatic headphones in order to provide a more full and robust bass response. The CRBN did have a slightly more robust low end, but in my opinion, it wasn’t that much more than neutral, and the trade-offs in terms of usability of the headphone were not worth the payoff in terms of low end.

The main problem was that due to the looser driver tension, the drivers would stick to the stators when listened to at a medium-high volume level or above, and distort. Now, due to the way the driver is made with the carbon nanotubes, no damage will occur from it sticking to the stators, but it will directly impact the sound and distort. Not good. In addition to that, any air pressure change inside the extremely well-sealed cups would cause the CRBN drivers to stick to the stators, and again distort. Again, due to the extremely good seal the CRBN pads provide, even slight head movements, could cause this to happen. I usually do my concentrated listening lying in bed at night, and any small movement of the headphones against the pillow would cause a loud driver flex noise, usually a loud cracking type of noise, and the driver would stick to the stators. Each and every time the driver of an electrostatic headphones sticks to the stators, you have to unplug the headphones, short the pins on your thumb or similar to de-charge the diaphragms and then plug them back in to go back to listening. With the CRBN in its original form, this was happening every couple of minutes or so. It was incredibly frustrating. Audeze has great customer support, but as the headphones were functioning within their expected performance at that point in time I ended up selling them to someone who could make better use of them, as they might listening differently than I do.


Over time, there were many similar reports to mine of people struggling with the same issues on various headphone forums, head-fi in particular. Around April of 2022, some rumours began circulating, that Audeze had made some changes to the CRBN and how their drivers perform. I was never able to receive direct confirmation from Audeze whether this had happened or not beyond a statement saying they had “streamlined the CRBN driver production.” Still, there were enough reports of it on Head-Fi, and users reporting that they had sent their headphones in to Audeze to be looked at, and received them back entirely absent of all the diaphragm sticking issues they had before, to make me curious. I ended up purchasing a pair of CRBNs that were a post-April 2022 manufacture date, to see if there was any validity to the claims of changes to the manufacturing of diagrams. My best guess is that slightly increased the tension of the diaphragm to avoid the issues of the early models.

Thankfully, the more recent pair of CRBNs had next to no issues. I managed to get the drivers to stick two times, once was with a fairly substantial bass boost at higher volumes, and another was due to a random head movement that cause the seal to break. Overall, the CRBN was now an entirely usable functional electrostatic headphone, it acted as my other electrostats did, and had no real issues in terms of overall usability. Audeze now seems to have companies list the CRBN as being the “2023 update.” Someone on head-fi confirmed that this was in reference to the driver changes that appear to have been made around April 2022. Again, I’m not operating off of direct knowledge here, just best-guess dates based on others’ experiences and interactions with Audeze. Overall, I would have no hesitation recommending someone try the CRBN now, with regards to production quality and overall usability of the drivers. Also, I know that if you do have an old model, made near the beginning of their production, if you send it in to Audeze they will update it to the most recent specifications. For anyone out there reading this, if you have a pair of early CRBN, and are struggling with this issue, I would highly recommend sending it in to Audeze. The update made them much more pleasurable to use.

Now, with all that backstory and information out of the way, the real question is how does the CRBN sound?

Tuning​

The bass of the CRBN is certainly a slight improvement over some electrostatic headphones. In particular, the SR-009 comes to mind. Much more physicality to it, and a slight increase in terms of level. Still, I don’t want to give the impression the CRBN is a bass monster, because it isn’t. I always ran the CRBN with a 3db low shelve, as I always prefer a more robust bass response over the more neutral response from most electrostatic or planar magnetics. In some ways, the CRBN makes me think of planar magnetic bass, more than electrostatic bass. It is quick, fairly dynamic and hard-hitting, though not as much as something like the AB1266 from Abyss, or the HE6 from Hifiman. I think that part of the reason the CRBNs bass is as well done as it is due to the incredible seal achieved with the CRBNs pads. They are without a doubt the best sealing electrostatics I have experienced, and this might contribute to that real physical feeling from the low end.

The mids of the carbon are hit-and-miss for me. In the low and middle midrange, I’d say that the CRBN are pretty much dead on neutral. No real warmth in the low mids, and definitely no suck out in the middle. My issue is with the upper mids of the CRBN, and it is my overall biggest gripe with their stock tuning. The 3khz peak. It is way too forward for me personally. Gives everything a shout and bite to it that I just can’t get on with. Some people enjoy this forward nature in this area, but for me, it just makes things tough to listen to. Thankfully, EQ resolved the issue entirely for me and took the CRBN from a headphone I couldn’t really enjoy, to one that had a ton of good things going for it. I would highly recommend trying the CRBN prior to purchasing them if you can, and if not, be open to giving EQ’ing them a try. It made all the difference for me.

The highs of the carbon are what I would consider very slightly less than neutral. Not enough to consider them a dark headphone, but they are not bright or strident headphones. Again, I ended up boosting the highs entirely with a high shelve by about 2 dB, and that brought them into my personal preference range very nicely. In some ways, the highs in their stock tuning remind me of the HD600/650. If you tend to prefer a bit more air and sparkle from your headphones, I would again recommend trying the CRBN prior to purchase or be open to trying out EQ. Again, this was an area that after a little tweaking via EQ, took the CRBN from a bit of a “not for me” to a “this is actually really, really good” headphone.

Technical Performance​

In terms of technical performance, the CRBN is clearly high-end. I don’t think they reach the sonic heights that the Stax X9000 and Hifiman Shangri-la Sr. reach, but comparing them to other headphones in their price range, I think they stack up well. Overall detail levels remind me of the LCD-4 (I have not heard the LCD-5 yet) and the CRBN always seemed to do better with the “macro” than the “micro” both in terms of detail and dynamics. Again, this sort of reminds me of the characteristics of some planar magnetic headphones and contributes to my feeling that the CRBN is the most planar magnetic sounding electrostatic headphone on the market. The soundstage of the CRBN is very tall, perhaps due to the driver shape, and what I would describe as very slightly wide. It is not a large open soundstage like the X9000 or Shangri-la, but also not a very close up and front-row type of soundstage like the Focal Utopia. The CRBN has a good amount of punch and slam to it, but I would describe it as similar to the LCD-4 in this way, and not as hard and fast in terms of slam as the HE6 from Hifiman or 1266TC from Abyss.

Build Quality​

The build quality of the CRBN is next level. Really, and I don’t say this lightly, I think the CRBN is the best-built headphone I’ve come across so far. It just exudes class and quality. It feels incredibly solid and well put together, the pads are deep and sumptuous. Comfort levels are very good, and the clamp force is just enough to provide their great seal, but not too much to be uncomfortable. Overall the CRBN gets an A+ from me in this area. Really well done Audeze.

The CRBN is slightly difficult to drive in terms of electrostatic headphones. You will be well rewarded for providing them with an amplifier that can provide good, and consistent power. Things like the Headamp BHSE, Eksonic T2, KGSSHV Carbon are all good options. I think at the least I would recommend a KGSSHV for the CRBN (or similar.)

Comparisons​

Compared to the headphone it is directly competing with, the Stax SR009S, the Audeze strikes an entirely different sonic signature. The Stax sounds like an electrostatic headphone and does all those typical traits very well. The CRBN has a better more robust low end and does not have the typical electrostatic air and sparkle in the high end. After a bit of tweaking via EQ, I think the CRBN would be my overall preference between these two headphones.

Compared to the LCD-4, the CRBN is similar in some ways but very different in others. The LCD-4 has “old Audeze” tuning, and the CRBN has “new Audeze” tuning if you will. The LCD-4 is much more laid back and relaxed, it is a warm hug of a headphone compared to the CRBN in its stock tuning. I think the CRBN wins in terms of overall detail levels and technical performance, but the LCD-4 is the right choice for someone who wants a laid-back listen that remains well detailed. I would be really curious to see Audeze continue to develop on the electrostatic side and perhaps do a CRBN Classic, which is tuned like the classic Audeze models. I think that might sell very well for them. Only time will tell if the market wants that product I suppose.

Conclusion​

Overall, the Audeze CRBN has been a bit of a saga for me. It didn’t really start out all that well, but Audeze has put the CRBN right and really has a good headphone on their hands now. Though the stock tuning isn’t personally for me, with some tweaking with EQ, the CRBN becomes an immensely enjoyable headphone to listen to. It is also the best built and high-quality feeling headphone I have come across so far, whilst remaining very comfortable for longer listening sessions. Nowadays, I can definitely recommend the CRBN if you either enjoy a mostly neutral tuning with forward upper mids. Also, if you are willing to EQ to your preference, the CRBN takes well to it, whilst retaining very good overall technical performance. The CRBN had a rocky start, but I definitely would recommend it these days, if you take into account the aforementioned points about tuning and personal preferences.

The workmanship of the headphone is really absolute top class. You immediately have the feeling that you are holding a high-priced object in your hand. It cost 4500 USD. The CRBN is light as a feather and very comfortable to wear, although the contact pressure could be minimally lower. Even then, it would still sit perfectly on the head. The leather pads have a very high-quality finish and are velvety soft, so they contribute to a pleasant wearing comfort. The pads have very wide edges. Nevertheless, there is still enough space for the ears due to the diameter. I think Audeze chose a smaller cutout here to create more bass pressure, which has also succeeded! Electrostatic typical, you can also create the "Stax fart" with the CRBN. Strangely, more often when putting the headphones down than when putting them on. Once I put them on, I could not create the effect even with rapid head movements. You have to press hard on the ear cups from the outside, which does not happen in practice during a listening session.



Funnily enough, when my CRBN arrived, I spoke of the LCD-5's "brother". After the first listening session, it was clear: these two have more in common than I thought! If you compare both you think you are comparing two electrostats. The LCD-5 sounds so little like a orthodynamic, like no other of its kind. The cleanliness, speed and resolution of both is on a level that currently marks the top class. I can't pick a winner here.

First, I compared the two without EQ. The CRBN has more bass volume and minimally more illumination in the treble. However, less in the highs than the measurements suggest. The LCD-5 probably makes up for this with the somewhat leaner bass range. Both are very midrange-focused. When I first heard vocals with the CRBN I was stunned. Patricia Barber, Steven Wilson with such a realistic, goosebump-authentic representation that is already great. The LCD-5 can't quite keep up in this discipline, although vocals are reproduced very cleanly, clearly and genuinely. Before I put on the CRBN, I didn't miss anything here. But when the CRBN got going, I noticed what was missing before.
In terms of stage, I see slight advantages with the LCD-5, which is a bit more airy and spacious. Left and right seem wider than on the CRBN. However, the CRBN has an insanely suggested depth for a headphone. Amazing! Both have absolutely razor sharp pin point localization of individual sound sources. I suspect that Audeze had to compromise on "airiness" to achieve this strong bass range.



For an electrostatic, the CRBN has a very punchy bass that also reach really deep. Even if you change from a 1266 TC to the CRBN, you miss nothing. The CRBN reach even deeper, but doesn't have the visceral impact of the 1266 TC. No Stax can do it like the CRBN, not even my 007, which has more midbass. But breaks further down, where the CRBN does not even batting an eyelash. For me, the CRBN has the very best bass I've ever heard in an electrostatic! Without EQ, the LCD-5 seems slimmer in volume, but it still punches a bit tighter in the midbass range. It lacks a bit of subbass, which the CRBN has in abundance.

I then compare the LCD-5 with EQ (Resolve v2) against the CRBN, I don't see any other discipline where the CRBN comes close to the LCD-5, except for the insanely well-rendered vocal range and the better depth staggering. The LCD-5 is then tonally perfect with bass volume, as the CRBN brings from home, but with a punch that clearly adds to it, downright noticeable. The CRBN is then a bit too warm in comparison, too superficial in the mids. The LCD-5 has the advantage to play big even on a DAP, since no particularly powerful amplifiers are necessary for its operation. If only everything would be so simple? The CRBN has something in its presentation that I can hardly describe. It invites you to sing and bob along and some vocals really give you goose bumps. The CRBN is also inherently better tuned than the LCD-5, which has me without EQ too little bass and plays too superficial in the mids. The CRBN also has superficial mids, but manages through this insanely "real rendering" of the voices that you hardly get enough of it and it never seems too concise. Maybe it's the electrostatic principle that makes them come across so buttery smooth and real? I don't know. It's not for nothing that people talk about the magic in the mids when it comes to electrostatic.

For someone who doesn't want to use an EQ and has an electrostatic amplifier, the CRBN is the better choice. It is already very well tuned out of the box. By the way, the CRBN is very efficient (much better than the 007) and no problem to drive. I hardly ever turned up my KGSSHv Carbon above 10/11 o'clock. But if you want to use an EQ you can get so much more out of the LCD-5 and get a sound that is then among the best in the headphone field. And this also on mobile on a DAP. You can probably get even more out of the CRBN with EQ. A little less mids, more treble and it comes very close to the LCD-5 with EQ already, because both are similar in many aspects as I described. However, I have not tried EQ with the CRBN. I like the CRBN as it is. This was not the case with the LCD-5 from the beginning.

With CRBN + LCD-5 one thing is clear. Audeze has now left the path of the typical "Audeze house sound" and navigates more and more to a more neutral presentation.
My longtime number 1 electrostatic the SR007 MK2 SZ21xx bass port mod has now met its match in the Audeze CRBN!