Katz's Corner: The Great Headphone Shootout. Part 5: The Revisions

EQs, Cabbages, and Kings
So, I purchased the LCD-X. When my new Audeze phones arrived, I immediately discovered they have a bit less bass than the demos I had auditioned and a bit more upper midrange (around 5-7 kHz). In the upper midrange they are a bit more forward and resemble the upper midrange of the 3s that we had tested. In the bottom, they are a little lighter, and I definitely miss some bottom. Basically, the demo unit was more accurate (neutral) than the one I purchased. I bet this is normal unit-to-unit variance, but I hope that the bass will come up upon break-in.

The Stax EQ
It wasn't long before I decided to tweak (the itch that every audiophile gets). I've seen some reports that the Stax 007 MkII (the "Omegas") sound a bit bassy and dull, but I don't have that reaction with the KGSS amp and a superior DAC. My precious Stax is clearly missing something in the bass department and I wanted to see if I could transfuse the slam of the Audeze into the Stax and have the best of both worlds. So I spent a weekend tweaking EQ with DMG audio's excellent digital equalizer Equilibrium inserted into JRiver. I didn't stop until I felt that a tenth of a dB change of any band in any direction made the sound worse, which in this case means "less authentic". Let's take a look at the Stax EQ that I arrived at:


As you can see, it's totally flat from 200 Hz on up, with a gentle low frequency shelving boost starting below 200 Hz, arriving at a little under +2 dB by about 55 Hz. Another important part of the equalizer is the subsonic filter, which some might not desire. But keep the following point in mind:

With headphones, subsonic level (let's say below 25 Hz) is the most subjective judgment. We are simply not built to accept sub bass information (like the thud of a bass drum) located inches from our eardrums. Besides, subsonics with this kind of strong air pressure change could conceivably damage our eardrums—I began to get a headache from strong bass drum thuds without the subsonic filter. Remember my Stax's are modified with the sealed port so they go down low—they exhibit the famous "Stax fart" when putting them on. In contrast, the loudspeakers in my mastering room are flat to below 20 Hz and the subbass sounds exactly right when reproduced from 9 feet away. With loudspeakers we get both the sounds that arrive at the ear and the physical sensation in the chest and body, which become part of the total loudspeaker listening experience. Using Acourate Convolver software, the wavefront from my two JL subwoofers is tight, time-aligned and phase corrected—with effects movies, the low frequencies shake your pants legs!

But that physical experience is missing with headphones and the brain has to adapt to hearing bass energy so close to the ear. Maybe I should put a butt kicker in my chair when listening to headphones! (Ed Note: Take a look at the SubPac, Bob.) So the amount of subsonic level in headphones is quite subjective and with sealed, fast, large diaphragms like the Stax, it's likely we will need a high pass filter. In the case of my Stax this is even more critical, because having sealed up the port, the seal from the surrounding cushions is so tight that air pressure changes in the diaphragm are virtually coupled to your eardrum. All transducers are by nature a highpass filter, but surely very low frequency in the case of the extremely light and responsive Stax diaphragms and a direct-coupled amplifier.

Those of you who have not experienced extreme subsonics have probably been listening to dynamic headphones, which do not appear to extend as low as electrostatics, at least the ones I've experienced. Subsonics can become painful, and this sneaks up on you without realizing it, because the sensation which normally shakes your pants legs is now directly shaking your eardrums, and besides, not translating into much sound perception. Pain is a very bad sign that something is wrong. If you feel pain at any time when using earphones, remove them immediately. Stop listening for that day and make sure you correct the problem for the next day, whether it be from listening too loud, or to those subsonics which nature did not prepare us for.

The DMG Equilibrium can perform linear phase or minimum phase equalization, and in the case of the Stax EQ, I chose minimum phase because it sounded just a hair better. After arriving at my "perfect" EQ, I created a Dirac pulse in Acourate and played the pulse in my Sequoia DAW at each sample rate, capturing it through the EQ. I then transformed the result into filters for use in Acourate Convolver. AC is so versatile that I was able to add the Stax EQ, and later an LCD-X EQ to my digital filters/crossovers and route each filter to a separate DAC destination. I now use 12 channels of DACs! Eight channels for loudspeaker 5.1 with stereo sub bass management, and 4 more for the two separate headphone equalizers. I have four channels left over in my Lynx AES-16 interface so if you have any ideas, let me know :-).

Remember to drop the level when performing any EQ boost, to keep the EQs from overloading. Mine is set to -3 dB. Those of you bit-counters who are afraid of losing resolution with DSP should have no fear, there's so much "footroom" available in properly processed and dithered 24-bit audio that even after processing it still is much quieter than the quietest DAC or preamp. Since Acourate Convolver is a 64 bit floating point DSP, it can do many calculations until the final one, which is a dithered wordlength reduction to 24-bit fixed point to go out to the DACs.

I spent one year carefully comparing, switching back and forth between my old, pure-analog crossover and analog volume control versus Acourate Convolver's digital version before I decided to ditch the analog system. By that time I was certain the Acourate Convolver sounds as pure, deep, big, and transparent as analog processing. That was not the case with other digital correction systems I tried, so it's still true that the devil is in the details.

In a moment I'll tell you how the Stax EQ sounds, but first let's tackle....

As I mentioned, this sample of phones is a little light in the bass and has a bit of a presence boost circa 7 kHz. I am hoping that break-in will raise the bass, but regardless, this bass boost restored all the heft and punch that I was after.

Here's the LCD-X EQ that I arrived at:


Let's look at the bands from low to high. I debated over it, but I decided to apply a subtle high pass filter to the X's, because their diaphragms are also quite fast and the seal is quite good. The subsonic rolloff I applied is almost inaudible; I still have to experiment with taking this filter in and out. It may protect our delicate eardrums from subsonic pulses that we cannot directly hear. From about 200 Hz on down is our bass boost. Hey, this looks just like the Stax boost. Unfair! Maybe I went too far, but it's hard to be objective, our ears are subject to "psychoacoustic ratcheting" which means that the more you boost, the more you want. Even when you A/B compare against the loudspeakers. So I probably went too far with the Xs.

My good friend Robin Reumers, who was my assistant several years ago, visited the other day and he feels my Stax EQ is a bit too much as well as the X. I disagree about the Stax, but we may only differ by a 1/2 dB. I know Robin's ears very well! The next band is a dip to deal with the unwanted presence boost in my Xs. I don't think I hit the nail on the head with that yet because there is still some sibilant distortion which is not present on the Stax or the loudspeakers.

With the last band I experimented with linear phase and changed to minimum phase. The difference is that linear phase EQ preserves depth but with minimum phase the image moves forward or backward depending on whether you boost or cut. A loudspeaker/earphone is by nature a minimum phase transducer so a complementary equalizer will likely cure its faults. Regardless, since to my ears the X's native response appears to take a nose dive above about 12 kHz, this band is quite subtle and does not make up very much for their lack of air.

The air band of the Stax is still a question in my mind, I'm considering experimenting with a tiny rolloff as there is clearly a rise in the Stax above 1 kHz. Worth playing with just to see what happens. But the Stax inherent rise is so gentle and natural that somehow it sounds pure, extended and open without an obvious brightness, without exagerrating sibilance or being bothersome. So, a high end corrective EQ would have to be very subtle, a few tenths of a dB at most. On the other hand, my old SRD-5's are almost brittle by comparison. Time to play with an EQ for them. Are we having fun yet?

The New Verdict
After the Headphone Slutz meeting I decided to feed the Stax amp with my Forssell MADAC, an excellent performer, and the Burson/LCD-X with a Slim Devices Transporter that I no longer use as a music player, but it has a superb D to A converter. That way I can digitally equalize each headphone separately, all managed within Acourate Convolver. I can switch back and forth between flat or EQ'd with the push of a single button of AC's remote control. This is the proof of the pudding.

The bass boost in the Stax is a winner, it's more solid and it doesn't hurt any of the other ranges. Changing back and forth between phones, the major differences between the Stax and the X's have greatly dissolved. The two phones are much more compatible. This EQ preserves the virtues of each phone while reducing their defects. What was previously two sets of grade A cans is now A+ for sure. Now I can listen to the music on either phone and bathe in its glory without getting itchy.

I can no longer tell you which is my favorite. The corrected Stax still retains the Stax character; it doesn't have the cojones or the punch of the corrected X, but the Stax is now solid and satisfying. At this point the weak link of the X is its air band and I doubt we can do anything about it, unless Audeze themselves can make a lighter, more responsive diaphragm. Or perhaps the lack of air has something to do with the Fazor. Some people don't miss the air at all, but I do. The corrected Stax doesn't have any obvious weak points and it's light as a feather, so I tend to pick that one up for pleasure listening, though tethered by a high voltage cord to a single spot in the house. The two equalized phones are very complementary; when I get the urge for punch, or when I travel around the house with my iPhone, it's X time!

The Punch Line
My theory why the Xs are so much punchier than the Stax is not because of frequency response. I think the slower and heavier diaphragm acts a bit like a bass-frequency compressor, softening and reshaping the transients of the wave just enough to give it strength and power. Magnetic force is non-linear, though Audeze has taken great effort to cancel those non-linearities with a push-pull approach. The electrostatic push-pull design has inherently lower distortion because capacitive force is more linear than magnetic, and the lighter the diaphragm, the easier it is to move and control its movement, to make it stop and go. Like my little Mazda Miata, which can stop on a dime. Objectively, the Stax is probably more accurate in the bass, with the lowest distortion, more accurate than any moving coil transducer, including most loudspeakers. But I think we crave some distortion: The Audeze cans are so seductive and likeable! When does high fidelity cross over into a matter of taste? "Objectively correct" has not always sounded "subjectively correct".

Consider both of these EQs to be works in progress. Very mature, though. If you would like to try something like this, don't take my settings as gospel, just as general directions and amplitudes you can try.

The Last Word Belongs to The iPhone
Since the X's are so efficient, I decided to plug them into my iPhone 6 with the included 1/4" to 1/8" cable adapter. All the files on my iPhone are 1644 ALAC, so we're a big step past mp3 or AAC. I was quite pleased with what I heard. The subtle upper midrange presence of my Xs is the perfect complement to the lower resolution DAC and material in the iPhone. I didn't even notice a bass weakness. This was instantly the best iPhone headphone experience I've ever had. But mostly it's a proof of performance because how do you expect me to carry around a set of X's? You can't jog or dance with them, either. But at least I can play them all around the house! Here's a photo of Bob traveling and dancing with LCD-X's on my head.


See you next time, whatever adventure comes our way.

Jim Tavegia's picture

I know it will benefit you greatly, but still is informative for the rest of us.

I only live in AKG K701 and K271 mk2 land and don't have killer headphone amps, but the idea to take what you have and slightly enhance it with EQ IS something we all can do. I think the thing to remember is just a little boost can go a long way.

markus's picture

The HE1000s have a thinner diaphragm than the 007s and yet produce such an impactful bass. Who can explain me why the Stax lack that awesome slam?

Seth195208's picture

has to be thought of with the traces included in the weight. That makes the diaphragm heavier(Probably much) than the 007's.

Beagle's picture

...or does it just "sound" impactful?

tony's picture

Nice work

I've been building my modest system for 3+ years to achieve acceptable results, finally.

Today I had another Audiologist evaluation to discover further deterioration.

I realize EQ will be part of everything in my Audio world, there seems no chance of any device popping out of the box and not needing.

The good news is that folks with 7 decades can have wonderful music systems and very good hearing or at least acceptable auditory experiences.

I am inspired by reading your workings and results.

You professionals struggle as folks like me but with much higher stakes riding on your results.

If I ever had 20 to 20k hearing it's lonnnng gone, I'm now living with 8k tops.

And I've learned that everyone hears differently.

I've learned that all transducers present sounds differently.

Even the same model headphone has ranges of performance.

It seems that every headphone out there has someone it's ideal for.

For me, headphones are like hamburger from the butcher shop, they come needing seasoning, seasonings my ears,bones, brain prefer. It's up to me to discover some desirable combinations.

This is hard work needing "skilled" technical guidance, good results don't come by happy accident.

This site Innerfidelty is the only place, I'm aware of, that examines these auditory issues scientifically and usefully for any reader ( student ) to explore and benefit from.

I'm confident that a great many people understand these scientific principals but very few can relate them to curious readerships.

Thank you for enriching me with your discoveries.

I am pleased with the results you discovered.

I anticipate you will continue discovering and reporting,

I'll be "all ears" for your writings.

Tyll is lucky to have found you, I suppose "Birds of the feather, flock together", we are all lucky to have found Tyll.

Tony in rainy Michigan

Bob Katz's picture

Love to hear your comments! I'm not getting any younger, either.

tony's picture

Tiger Woods, at 39, is falling apart, it seems.

He missed the widest Fairway in the Game this weekend.

I'm at 4 diopters with vision and getting worse.

Good news is that we can correct, mechanically, never gonna be as good as before but our Brains re-calibrate constantly so we don't quite notice until we take that big Test and realize the new realities.

Poor Beethoven went Alcoholic trying to cope, he died young with a blown-out Liver.

We have Eyeglasses, BTE hearing assists, iPhones with their increasingly complex solutions to the human condition. We live a better life than anyone in history.

I'm ready for the next advancements.

Tony in Michigan

zobel's picture

You mentioned that your copy of the LCD-X has a a little too much output in 5 to 7kHz range. Wouldn't that be mid-treble, not upper midrange? Also, isn't the presence range the low treble, 1 to 3kHz, or do you think it is higher, say 2 to 5kHz? People tend to refer to the audio glossary by J. G. Holt, to try to keep on the same page in terminology, though it probably could use some amending. You have no doubt seen it;

Assuming no EQ being applied, which set of cans would you prefer, your Stax or your Xs just on sound alone? If you could only have one to make masters with, what would it be, or do you have other cans you use?

Again, thanks for the report!

Bob Katz's picture

Zobel: There is some debate over where the mid-treble and upper midrange break off. Same with upper bass and lower mid. I never read Gordon Holt's recommendations on it, so my vocabulary is mine. I'm too old to change, having used my own breakpoints on the frequency ranges since 1971 :-).

Which can do I prefer this week, without EQ? The LCD-X. With EQ: The Stax. The Stax regain some power in the bottom and their open, clear and extended high end and imaging plus their light weight make them the winners for me, with EQ. So if I had to make masters using headphones, it would be the EQ'd Stax with the KGSS amp. They are as accurate, extended, transparent and musical as you get. And second place: The equalized LCD-X. Hope this helps.

castleofargh's picture

having someone respected, to talk about using EQ, that's sadly not something we see often enough. I'm always flabbergasted when I see people accepting the crazy weird signature, crossover massacres, or just overall impedance/phase changes in headphones/iems as if all was good and a matter of taste, but at the same time call an exorcist anytime EQ is suggested. audiophiles can really be the most irrational creatures at times.

also about EQ, it's the first time I read about the change in imaging from EQ being linear or minimum phase. the change in imaging from using EQ is something I clearly hear, but I never tried to test if something was different with linear phase EQ(or more like the one time I tried to test failed to show me anything significant). I just thought that our ear relying on FR for stuff like vertical positioning, it was logical to get a change in imaging from an EQ.

but as it happens I've been using minimum phase EQ for many years, so I'm not in a position to prove even to myself that I disagree. ^_^
but aren't you pushing on stereo listening, the effects you've had from mixing several channels? because with several sources coming together, there minimum phase can make a clear difference, but does it do anything meaningful when EQing 1 single signal?
I'm using all the free vst stuff on foobar and what I've tried didn't offer both filters in one box(or I missed it maybe?). if somebody knows of a free, not too buggy(or good and really cheap) parametric vst EQ that allows to switch from minimum to linear with the same EQ, I'm interested to test that imaging change proposition. EQuilibrium is too expensive for me, I do like to use EQ but I have a hard time justifying such a price difference from some already pretty cool free EQs. more so when I'm clearly an amateur when it comes to use an EQ so I would probably not know what to do of 2/3rd of the features I would be paying for.

Bob Katz's picture

Dear Castlefargh: Tonal balance has always been important to me. The people who are afraid of EQ seem to forget that if a loudspeaker has tons of inductors, capacitors and resistors and has been voiced by the designer, that is EQ. Let me say that again: That is equalization.

However, the vast majority of analog equalizers I've known over the years have either not been transparent enough, resolved enough or finely tuned enough to make them worth it. I've inserted many and pulled them out of my system. Just didn't work. Prior to using Acourate convolver I was using in the subwoofer channels only a Meyer Sound 1/6 octave parametric with screwdriver trim controls. It was more than accceptable in the sub channels only. It wasn't until I found Acourate Convolver that I would EVER consider digital EQ in my system. Most digital equalizers have their own faults.

So I can understand some audiophile's resistance to EQ. Most EQs they find sucked. UNTIL the best of digital came out. Be careful what you ask for. Equilibrium is very reasonably priced and it is the bees knees. Many other linear-phase-capable digital equalizers use very short impulse responses and screw up the low frequency response with all kinds of ripple. So make sure your impulse response is set to at least 32K samples, preferably 64k samples (nominally) especially at higher sample rates. There are other issues with FIR EQ and it has to be done really right to sound great. And Equilibrium does it right. Then do not forget to dither to 24 bits on the way out to the DAC.

If not, then your digital EQ might as well be lowering the transparency you are trying to improve. With the very best, though, (that is, for example, Equilibrium) I can attest that digital EQ is transparent, pure, accurate, and just does the job of countering the issues in your headphones or loudspeakers. If you tune it right, it will sound as warm and transparent as any of your all-analog systems used to sound. If you use a poor digital EQ or tune it wrong, you'll be screaming "I hate digital" all the way to the bank. Equilibrium is not your mother's digital equalizer. Acourate Convolver is not your mother's digital room correction system, and that means that people playing with low end DRCs are missing more than if they just pull it out and live with the sonic errors. Believe me, I know where most of the bodies are buried.

tony's picture

Not easy to understand, embrace or use properly.

I rather suspect we all would need a skilled tutor and guide to coax us into a good result.

You professionals have the background and access to Factory trained technicians that we amateurs will never realize until we hire a skilled and patient "hand holder" who sells these solutions to "consumers".

My most recent Audiologist testing reveals my personal freq. response curves ( combining direct hearing, bone conduction and brain processing ), I hear differently than one year ago and my brain processes differently.

I can and do use Analog EQ to compensate for me and my HD580s to a ametuer level of acceptability.

I am curious about your Acourate, I just had a look at their web page, phew, this seems to need a good bit of study and explanation. It is dirt cheap though so it's not like wasting a couple of grand sort of thing. But I'm getting into the deep waters here, way deep!

Superb musical renderings have the affect of releasing dopamine in the Brain, the better the rendering the greater the dopamine release to the point of music becoming an addiction which is probably what this audiophile business is all about.

I sit here with hearing correction ( from Age ) and a vast music collection playing thru a Schiit/Sennheiser drug delivery system. My wireless are a low grade of Codine, my Big Schiit/Sennheisers are a medium grade of Heroin. I am happy with both as they are.

I think that I understand my next step-up is to hire a skilled person to build a much better system.

I probably have gone as far as I can go with my skill level and experience.

At some point I may want a better Buzz, I'd better prepare for that day. So: I'll stay tuned.

I'm hoping to follow you into that "Big Rock Candy Mountain" of Stax and Gilmore and wonderful recordings, though my wife prefers me to stay in the flower beds pulling weeds.

Balance in all things,

Tony in Michigan

castleofargh's picture

right now isn't the best of times for me to test all that(summer is summer and I'm not home), but I'm certainly interested and will try the demo when I'm back, if only to fool around with different filter modes.
I still feel like it's giving spam to a pig when I'm really not experienced enough in EQ to justify the price of equilibrium. not that I can't afford it, if I can put money in a DAC or an amp I can do it for a good EQ. just that I'm an amateur newbie who most likely will never be able to tell the difference with anything else.
maybe if they use the same engine, I could settle with EQuality instead.
anyway thank you for your time, you certainly have made me curious and reading about equilibrium online, it does seem to have many supporters.
if I end up with an epiphany when I come back home and test the demo, I'll make sure to let you know all about it ^_^.

Bob Katz's picture

Equality's linear phase mode can be tuned to perform like Equilibrium, but the factory defaults use such a wide impulse response it can weigh on your CPU. Equilibrium seems to be better tuned to minimize CPU load out of the box. I like the interface and usability of Equilibrium so much that I ceased to use Equality. Ask the developer (Dave Gamble) if there's anything in Equilibrium performance-wise that you would be missing if you bought the lower priced Equality.

Bob Katz's picture

Here are some listening tests you can do with linear phase. Get a demo of Equilibrium if it's available. You may get hooked on it. I'm sitting on the fence about the virtues of low frequency and mid frequency linear phase EQ. I'm not sure I can hear the difference in the low end, and most times the minimum phase wins for me. But a high frequency boost, to correct issues in program material (softness in the high sound, muffled high end), sounds very very nice with good linear phase, whether you are listening to a purist minimalist recording or a multitrack. A boost or cut in minimum phase tends to smear the depth, to mess up the depth of the recording as well as bring the high frequency instruments closer or farther. A boost or cut in linear phase tends to preserve the depth of the recording. When the issue is the high frequency area of the recording, as a mastering engineer, I tend to prefer the linear phase 90% of the time. The improvement in holographic depth and preservation of the original depth is palpable, whereas when the depth is smeared, everything appears on the same plane. However, I preferred the minimum phase when boosting the high end of the LCD-X because it seemed to complement the phase errors of the dynamic transducers better, to my ears. The difference was subtle and I had to spend about 20 minutes deciding which I preferred. And I used as my reference recordings which I know very well as played on my Acourate-corrected loudspeakers, with excess phase correction that Acourate does so well. I asked myself, do I want this instrument to move forward? Which choice is more like the sound of the loudspeakers, and so on.

But if you are using an EQ to fix tonal issues in the recording (I guess recordings not mastered by me :-) then a linear phase is a good candidate. If it's to make a permanent fix in errors in your headphones, probably minimum phase is the best choice as it should be complementary to the phase errors in the transducers. That's my opinion based on considerable listening, but I'd love to hear your reactions. Good sounding linear phase equalizers have only begun to appear and none of us is very familiar with their artifacts and/or advantages. And we do not always hear phase shift either, as evidenced by the low end (bass) correction seeming to my ears to be preferable with minimum phase.

cundare's picture

This may be a dumb question, but why would "capacitive force" (whatever that is -- are you referring to electrostatic interactions?) be more linear than "magnetic force"? Aren't both described by the same (Maxwell's) equations?

I can imagine that some electrostatic speakers may be more (or less) linear, all other things equal, within certain excursion ranges or when producing output at certain ranges of sound pressure, but wouldn't that be a function of implementation details, not of whether a driving force is magnetic?

Bob Katz's picture

I don't think that's a dumb question at all. It's a very smart question and may be over my head! When I wrote that statement I thought about all the distortion of transformers and the non-linear BH curves of magnetic force and assumed (you know what happens when you assume) that those distortions do not apply to capacitors. I'll have to ask a physics expert I know to arbitrate this one!

Bob Katz's picture

Thanks for that correction. Cundare was mostly right and I was mostly wrong. Here's the answer from my "physics" friends on the Pro Audio list, Paul Frindle and Fred Thal:
Paul: "This is a complex situation.

The magnet and B/H curve situation does not affect earphones very much since the power in the coil isn't great enough to affect it. So I think we can forget that.

The biggest cause of LF distortion is the coil physically moving in the magnetic field changing the coupling (and compliance) as it does so. It's a big deal with speakers, but with phones this ought to be minimal at normal levels, but it is proportional to the level and inversely proportional to the freq in general.

But looking at electro-static phones the same is true, because the capacitance (and therefore coupling) changes as the membrane's distance from the fixed plate is modulated. The further away it gets the lesser force is applied. In this regard the guy is right - and measures are sometimes applied to reduce this, or at least change the harmonic content of the distortion from 2nd harmonic to 3rd etc.

The biggest real advantages in electro-static phones include the reduction of mass for the diaphragm (there are no heavy windings on it) - and the fact that the motive force is largely applied across the whole diaphragm, rather than applied by the coil in the center. Both of these factors significantly improve the situation for the diaphragm over the wide freq range required."

Fred: "> The biggest real advantages in electro-static phones include the reduction
> of mass for the diaphragm (there are no heavy windings on it) - and the fact
> that the motive force is largely applied across the whole diaphragm


And I'm in agreement with objecting to the term capacitive force.
(Probably not the best way to describe electrostatic transducer
operating principles.)

The diaphragm mass differences (planar magnetic versus electrostatic)
are huge and could well be at the heart of this matter."

I'd like to add that the extra large diaphragm of the Omega IIs contributes to its ability to produce a higher SPL with less excursion, which also would reduce distortion by staying within the linear region of the capacitance change. The extra large diaphragm of the Audeze LCD-X also contributes to their superiority. I think the large diaphragms are a significant development in headphone fidelity, they throw a larger image as well.

cundare's picture

Thanks for the well-reasoned reply. As you imply, the issue is nuanced. ("Back EMFs, anyone?") One reason I asked is that any mention of "linearity" in reference to real-world electrostatic transducers always grabs my attention. It was a little before my time, but, supposedly, that was Peter Walker's great breakthrough with the Quad ESL -- he found a way to actually build an electrostatic panel that was linear within a useful range.

Petrov7's picture

Hey Bob---
I watched the video of your Big Sound and the Harman Response Curve but I couldn't quite see the Equilibrium curve on the screen. Any way that you could email me a screenshot of it (I have a pair of LCD-X's now and am awaiting a pair of LCD-4's to arrive).