[stevehecht]

It occurs to me that this critical discussion of the place and value of empirical measurements in the audio world can be broadened in scope to the culture at large. I think we are all aware of a certain hubris associated with the position that scientific measurement is somehow more valid and real than is empirical sense impressions when used to evaluate the quality of sound reproduction. Of course there is no scientific proof for this meta-scientific claim, and the ideological commitment to this belief is known as scientism. Resistance to this philosophical position (as evidenced in this thread) is not only not un-scientific but is itself quite rational. Unfortunately scientism has always been been part of the culture of science and has been partially responsible for an equally unfortunate and irresponsible reaction in society leading to a distrust of ALL scientific knowledge, and for supporting the belief that scientists and science represent the interests and perspectives of a self-serving elite. This has real negative consequences in the world, as evidenced by (e.g.) the irrational resistance to vaccines in general and by the highly dangerous embrace of unproven treatments for diseases like Covid-19. In the audio world this 'cult' of "it can be measured so it must be important" has led to the embrace of uninspired and sometimes mediocre audio equipment and the dismissal of sonic sources that has brought great joy to the lives of many listeners.

 

[kkrazik2008]

You’re right, I don’t have much experience with Dan Clark headphones but on a different thread I had read some people reporting good synergy with Starlett and Aeon Flow so I thought it might work well with Ether 2 as well. But best to check with Donald for sure.

As one who owns the Aeon Flow and DNA Stratus, and also had a long term demo with the Starlett, this is bonkers. The Aeon Flow is a current hungry planar, and quite inefficient off both those amps. Will either amp get them loud, of course they will. I found them to be lacking, and ended up driving them with a few solid state amps to get them in a better spot. Of course everyone has a right to claim their preferences, at some point one can’t deny the physical obstacles with a low ohm, inefficient planar.

Now the Stratus and Caldera, quite the combo and was a welcomed surprise out of the 8 ohm tap. The second planar I have found to be synergistic with my Stratus.

One other amp that is also great for both dynamic and the new planar would be the Eddie Current Black Widow 2, though good luck finding one.

 

[busseysound]

Yes! This is true, depending on the driver in question. Sorry, I should have clarified but I didn't really want to get into it on that thread.

I think most people know that a headphones rated impedance is a nominal value, meaning the impedance is not constant across the frequency range, how flat the impedance curve is is dependent on the specific driver. With dynamic drivers, there can be resonances at low and high frequencies where the impedance will spike. Something called a voltage divider is formed between the output impedance of the amplifier and the impedance of the driver - essentially the output voltage of the amplifier is split across these two impedances, how much voltage is dropped across each will depend on the ratio of these impedances.

So, if the driver is being run by an amplifier with a relatively high output impedance, you may see a bump in the frequency response at these resonant frequencies as more voltage is being dropped across the driver due to the impedance spike at that frequency. If the output impedance of the amplifier is very low, then the impedance spike at these resonances becomes negligible in terms of frequency response since nearly all of the voltage will be dropped across the driver.

That's a pretty basic explanation without using math, but I hope it makes sense. There is tons and tons of info out there just on this subject if someone wanted to dive deeper into it.

So yes, that is one way tube rolling can affect the frequency response IF you are changing output tubes to different types that will significantly alter the output impedance of the amplifier. However, I don't think that explains a lot of the differences people hear when tube rolling, especially when swapping input tubes.

Often you will see people say "X tube is warm and Y tube is bright" even if the two tubes are the same model, say two different 12AU7 for example. If you were to measure the frequency response of the amplifier with these two tubes, you would most likely find it measures exactly the same with both! So why is there a perceived difference?

This is bit of a mystery, and I'm sorry but I don't have a definitive answer, but my suspicion is is related to the distortion characteristics of the tubes having a psychoacoustic effect. Since tubes are imperfect devices, if measured you will often see differences in THD between two tubes of the same type, even if they are both NOS measuring, which certainly is audible and will affect how someone perceives the sound.

Also, there may be some contribution from material and construction differences of the tubes. I think you'll find this isn't something that has been studied in any scientific way, but it seems to me there is enough anecdotal evidence to suggest plate / grid / cathode material and construction does contribute to the character of a tube's sound in a meaningful way.

But the point I was trying to make is that these differences truly are perceived, the amplifier's frequency response is not changing in any measurable way when you swap tubes of the same type!

To chime in with others, this was a great read - very informative. Thanks!

 

[senseitedj]

Last night I went to the Portable Audio Party Indonesia (PAPI). Its like a mini CanJam within the Indonesian audiophile scene. I got a chance to demo various ZMFs and other cool headphones such as the DCA Expanse, Diana TC. Hifiman Susvara, HE-6 and Brought my HEDDPhone along for everyone here to demo. It was unfortunate that the Caldera did not arrive as it was a highly anticipated item, but the rest of the ZMF stable was here. This is not a full review just a brief impressions

Listed are amplifiers that are an excellent match with ZMF headphones. ZMFs get along with many amplifiers giving different versions of awesome. To me, the combo that really stood out was the Burson Soloist GT and Atrium. I tried VO/VC as well and offered excellent clarity and good level soundstage also. Atrium stood out to me personally as I enjoyed the slightly darker FR, even larger soundstage and really punchy dynamics. VO/VC offered higher clarity and tighter imaging but a smaller soundstage, so it's really a matter of taste and I can see an argument where one would own both as direct compliments.

It's just for my personal preference relative to my headphone collection, the atrium provided a more unique experience - it sounds different than what I am used to, so the 'voicing' of the atrium really stood out to me. VC was also really interesting with the burson was interesting as it provided an out-of-your-head experience for a closed back with crisp imaging.

Compared to the Burson soloist GT in general, the HA-3A narrows the soundstage but sounds really fast, and notes the weight of notes in the midrange specifically, feel thicker relative to the burson, but about same level of punch and slam with burson when it comes to percussive instruments. The 300B on the other provides a larger soundstage compared to HA-3A but still smaller than the burson. The 300B still provides good punch and dynamics but has very soft leading and trailing edges of notes.

These are just brief impressions under noisy show conditions, but hopefully can be of some use for ZMF owners. Pictures are not complete as ZMFs were quite popular in the show.

Amplifiers with ZMF:
Chord TT2 HP out (I did not try this combo personally but others have really liked it)
Burson Conductor + D90 Topping
Cayin HA-3A + Chord TT2
Cayin HA-300 MKII + Cayin IDAC6 (with its matching transport)

 

[ziggz]

Adding some Solid State goodness to the Auteur Classic's.

 

[AudioDuck]

Nice- congratulations, a lot of people love the Ferrum gear- I’m sure it sounds lovely!

 

[ziggz]

So far so good, need more time with them to form a better opinion, but definitely one of the smoothest SS amps I’ve heard so far.

 

[Mau10]

Adding some Solid State goodness to the Auteur Classic's.

So much fun in such a small form factor !

 

[Barnstormer13]

As one who owns the Aeon Flow and DNA Stratus, and also had a long term demo with the Starlett, this is bonkers. The Aeon Flow is a current hungry planar, and quite inefficient off both those amps. Will either amp get them loud, of course they will. I found them to be lacking, and ended up driving them with a few solid state amps to get them in a better spot. Of course everyone has a right to claim their preferences, at some point one can’t deny the physical obstacles with a low ohm, inefficient planar.

Now the Stratus and Caldera, quite the combo and was a welcomed surprise out of the 8 ohm tap. The second planar I have found to be synergistic with my Stratus.

One other amp that is also great for both dynamic and the new planar would be the Eddie Current Black Widow 2, though good luck finding one.

I found the Aeon Flow Closed (AFC) to work very well on Schiit’s Folkvangr (FV). Yes, the AFC is a low impedance current pig and the FV is an OTL (though with some tricks up it’s sleeve), but of all the amps I’ve ever had the AFC hooked up to, the FV sounds the best by far. It won’t do super high volume but able to deliver 100 dB without a problem.

 

[haasaaroni]

Don't know if anyone else here has compared the Forge and Pendant SE, but I've got both here and am deciding between them for my ZMF's and Senn's. If anyone has any insights between the two, I'd be curious to hear them! Still gotta find better tubes for the Pendant, just using the vintage set provided by ZMF and a Brimar CV4003 I had from my Bottlehead Crack, while the Forge has Sophia KT88's and a Tung Sol 6SL7GT round plates.

So far the Aeolus seems to like the Pendant much more. An already warm headphone, the Aeolus on the Forge is like adding an Aeolus to the Aeolus. Such huge bass slam (dare I say too much?) and warmth without going into gooey territory, but it just mushes the sound together a bit too much. The Pendant keeps things a bit more separate and clean, gives them a bit more bite, and deepens the stage. I think if I still had a Verite Open or Closed, the Forge would be for me, but with the Aeolus (Auteur Classic is currently off getting a hardware makeover), the Pendant SE seems to be a better complement so far.

 

[Mau10]

Don't know if anyone else here has compared the Forge and Pendant SE, but I've got both here and am deciding between them for my ZMF's and Senn's. If anyone has any insights between the two, I'd be curious to hear them! Still gotta find better tubes for the Pendant, just using the vintage set provided by ZMF and a Brimar CV4003 I had from my Bottlehead Crack, while the Forge has Sophia KT88's and a Tung Sol 6SL7GT round plates.

So far the Aeolus seems to like the Pendant much more. An already warm headphone, the Aeolus on the Forge is like adding an Aeolus to the Aeolus. Such huge bass slam (dare I say too much?) and warmth without going into gooey territory, but it just mushes the sound together a bit too much. The Pendant keeps things a bit more separate and clean, gives them a bit more bite, and deepens the stage. I think if I still had a Verite Open or Closed, the Forge would be for me, but with the Aeolus (Auteur Classic is currently off getting a hardware makeover), the Pendant SE seems to be a better complement so far.

The Aeolus is a masterpiece, particularly with the universe suede pads to my liking. You can plug it to any kind of source and will always provide beauty and emotion in return. That being said, I concur with your findings, the Aeolus paired to the Pendant SE makes a very special match.

 

[haasaaroni]

I think we are all aware of a certain hubris associated with the position that scientific measurement is somehow more valid and real than is empirical sense impressions when used to evaluate the quality of sound reproduction. Of course there is no scientific proof for this meta-scientific claim, and the ideological commitment to this belief is known as scientism. Resistance to this philosophical position (as evidenced in this thread) is not only not un-scientific but is itself quite rational.

I totally agree! Glad somebody came out and said it.

Our culture has such a distrust of our subjective experience, but the reality is that all experience is so deeply conditioned and colored by our subjective point of view. There actually seems to be no experience at all without conditioning, at least no separate experience, since simply how we draw the line between one thing and another is completely open to interpretation. "Objective" measurements are likewise interpreted by a subjective point of view, deeply conditioned by thought, culture, language, past, and innumerable other factors. To be able to have deep trust in our own sense perceptions, while refusing to come to any hard conclusions, is to come home to what's real.

 

[Dawgfish]

As one who owns the Aeon Flow and DNA Stratus, and also had a long term demo with the Starlett, this is bonkers. The Aeon Flow is a current hungry planar, and quite inefficient off both those amps. Will either amp get them loud, of course they will. I found them to be lacking, and ended up driving them with a few solid state amps to get them in a better spot. Of course everyone has a right to claim their preferences, at some point one can’t deny the physical obstacles with a low ohm, inefficient planar.

Now the Stratus and Caldera, quite the combo and was a welcomed surprise out of the 8 ohm tap. The second planar I have found to be synergistic with my Stratus.

One other amp that is also great for both dynamic and the new planar would be the Eddie Current Black Widow 2, though good luck finding one.

I'm currently running my AFOX from an Ampsandsound Mogwai OG out of the 8ohm speaker taps using a banana plug to 4 pin XLR adapter. The synergy is exceptional and its pushing them surprisingly well with lots of punch and dynamics. I'm not posting this to be contrary just wanted to let other members know that the Mogwai pushes the Aeons exceptionally well. I finally found an amp that's equally good with high impedance dynamics and inefficient planers.

 

[Monsterzero]

My Aegis review, which is the tube amp I used in my Caldera review. Also comments on how it pairs with VO, VC, Atrium and Susvara

 

[goldwerger]

My Aegis review, which is the tube amp I used in my Caldera review. Also comments on how it pairs with VO, VC, Atrium and Susvara

Great review.

Now, as someone who hasn't built a bottlehead crack...can someone please build and sell these ? please ???