The Technologically Impressive LCD-4 Planar Magnetic Headphone

For me, the story of the Audeze LCD-4 ($3995) is primarily a story about invention, research, and corporate learning. Audeze's latest flagship, to my eyes, is less a simple product, and more an artifact evidencing the progress of a long and involved technical battle to take the previously underdeveloped planar magnetic headphone technology beyond the capabilities of tradition dynamic drivers. Make no mistake about it, Audeze is on that trajectory, and the LCD-4 provides an opportunity to take a close look at the work accomplished.

Briefly, the LCD-4 is a full-size, around-the-ear, open acoustic headphone and remains superficially much like its LCD-3 predecessor; differentiated by chromed grills, a 3-meter hefty blue cable, and sporting a very nice carbon fiber headband with a wide, floating, glove leather headband strap. Though a large and heavy headphone, I find its very ample and plush ear cushions and wide headband cozy and comfortable. You don't so much put these on your head as you do put your head inside the headphones. A sonic helmet of sorts.

Those that live in hot, humid climes may well be served by a cooler headphone; and folks with slight frames may find them too heavy. But for those intent to hear the drive and authority that planar magnetic headphones provide, I think the weight and warmth will amount to a minor inconvenience.

Also included is a hard-side, Pelican-case-like storage and carry case with locking closures. A perfect accessory to carry your cans to the next headphone meet.

Audeze and Technological Advancement
I'm very fortunate to have known Sankar Thiagasamudram, CEO of Audeze, since the very earliest days of Audeze's inception when they first showed a off-the-shelf headphone modified with their first prototype planar magnetic driver. Since that time, we've continued to meet at shows and talk about new products, of course, but more importantly for me, we've also spent a good deal of time talking about the technical adventure of advancing the state-of-the-art in planar magnetic headphone drivers.

In fact, a few years ago I arranged a visit to their headquarters to get a half day's lesson on how planar magnetic headphones work from Dr. C., Audeze's CTO. The resulting article can be found here.) This training in order to be complete included both on and off the record information, as has had many discussions subsequently. I mention this for two reasons: First, as a matter of disclosure; I do have a fairly regular relationship with the engineering team at Audeze; and am privy to a small but meaningful amount of propriety information. Personally, I don't have an ethical problem as dialog is always focussed on learning about this developing technology in an effort to understand it and be able able to explain it to InnerFidelity readers. I also don't think it effects or biases my judgements—I'll offer the fact that I recently removed the LCD-2 and LCD-3 from the "Wall of Fame" and wrote about past unit-to-unit driver variations.

The second and more important reason I bring up Audeze's technological prowess is because it's damned impressive. I've been to the labs at Sennheiser, AKG, and Beyerdynamic; and I used to visit all manner of super-high-tech labs as a scanning electron microscope technician. While Audeze's lab is of small size in comparison, it remains an awesome experience to go into a room with a couple million dollars worth of gear and more than one doctor in some exotic specialty with their faces pressed up against computer screens flickering with color as they closely study finite element animations. This is clearly a place where the boundary of the unknown is slowly but surely being brought into view, and earshot, for us all.

LCD-4 Technological Detail
While the LCD-4 looks quite similar to the LCD-3 from the outside, they are quite different on the inside. Differences include:

  • Sub 0.5 micron diaphragm.
  • Uniforce diaphragm circuit.
  • Fluxor magnet arrays on both sides of the diaphragm.
  • Fazor acoustic impedance matching elements on outer and inner side of magnet arrays.
  • Aperiodic ear-pad vent.

Audeze_LCD4_Illustration_LCD4MagneticCircuit

Most of the dialog on this page refers to this diagram, which is for illustrative purposes only and is not at all to scale.

Diaphragm - Audeze characterizes their LCD-4 diaphragm as "nano-grade". The actual dimension is proprietary, but Sankar told me it was sub-0.5 microns thick. For scale, a human hair is about 100 microns in diameter on average—200 times thicker than the LCD-4 diaphragm.

Diaphragm construction is a fairly lengthy and largely propriety process. Basically, the material is drawn through a device that slowly deposits a very thin layer of Aluminum on the surface, and then spooled onto another roll. When the entire roll is on the take-up spool it switches directions and the process is repeated. Audeze claims this very gradual rate of deposition ensures the aluminum layer has an extremely fine grain structure. Stress factors under mechanical load will often cause failures the originate at grain boundaries, and therefore, smaller grain structure is preferable. From Wiki here:

Fatigue occurs when a material is subjected to repeated loading and unloading. If the loads are above a certain threshold, microscopic cracks will begin to form at the stress concentrators such as the surface, persistent slip bands (PSBs), and grain interfaces.[1] Eventually a crack will reach a critical size, the crack will propagate suddenly, and the structure will fracture.

Audeze believes making the aluminum with a very fine grain structure will reduce failure. Additionally, thinner traces will reduce stress in the bulk of the material. When the LCD-4 was first introduced it had a short run of headphones with a 100 Ohm impedance. This was quickly changed to 200 Ohms by halving the thickness of the deposited aluminum layer. I assume this was done to reduce the possibility of stress fractures, and therefore failure by open circuit of the diaphragm circuit traces. Audeze will replace the drivers of anyone who purchased the 100 Ohm version of the LCD-4 with the newer 200 Ohm version if they so choose.

Once aluminum deposition is complete, the diaphragm undergoes another proprietary process to remove the unwanted aluminum, leaving the only the finished diaphragm circuit traces.

Uniforce Diaphragm Circuit - Although the Fluxor magnet array does a very good job of producing a magnetic field with evenly distributed strength (isodynamic field), there remain small differences in magnetic field strength over the surface of the diaphragm. If all the circuit traces were of the same size and evenly distributed over the diaphragm surface, the varying magnetic field would cause the motive force of the circuit traces to fluctuate from position to position across the diaphragm surface. This unevenness of force acting on the diaphragm surface may instantiate modal break-up (Eigenmodes).

Audeze's Uniforce circuit combats this possibility by unequally distributing the position and width of traces such that they provide equal motive force within the varying magnetic field. They claim it delivers more even and predictable diaphragm movement.

Fluxor Magnets - I very clearly remember my palm meeting my face when I first heard about this design; "D'oh! Why didn't I think of that!" The Fluxor magnets are essentially a pair of magnets polarized from corner to corner and brought together to cause the main poles of the magnet to sit at the outside corners nearest the diaphragm. This concentrates the bulk of magnetic field at the diaphragm.

Audeze_LCD4_Illustration_HowFluxorMagnetsAreMade

My initial wonder of how something might be magnetically polarized corner-to-corner was punctuated by yet another self-induced slap to the forehead when I learned a large neodymium bar magnet is simply sliced and diced on a forty five degree angles.

This configuration produces 1.5 Tesla of magnetic field strength at the diaphragm, which Audeze claims is the highest field strength in any headphone made today. I find it beautiful in its simplicity.

Fazor Acoustic Impedance Matching Element - Fazor elements are positioned on both the inside and outside of the driver where sound exits from between the magnets. These elements are designed to provide a smooth transition for sound as it passes from the diaphragm, through the magnets, and toward the ear (or the outside of the headphones).

There is an opinion floating around the enthusiast community that the Fazors did something negative to the sound. It did appear to me that bass level did drop slightly around the time of the Fazor introduction, though I'm not sure this was the symptom noted by enthusiasts. I would urge caution in ascribing any changes in sound solely to the Fazor—Audeze (and most all manufacturers of complex gear) continually change product for performance improvement, but also for manufacturability and supplier parts availability. I suggest there may be other reasons for the perceived change at the time of the Fazor introduction. I've seen some pretty convincing evidence that the Fazors are a net positive in Audeze driver performance.

Aperiodic Ear Pad Damping Ring - Well...that's not what Audeze calls it. New to the LCD-4 has what looks like a felt ring between the base of the ear pads and the capsule housing of the headphone. Audeze claims the main purpose for this ring is to provide a slightly lossy ear chamber for the headphones. When you put headphones on, air trapped in the ear chamber of the headphone can exert significant pressure on the diaphragm. With some headphones (not just planar magnetics) if you push the headphone against the side of your head while being worn, you can hear a crinkling sound. This happens because air trapped between your head and the headphones increases pressure as you push in, and this pressure against the diaphragm can, at times, deform the diaphragm much more strongly than even a quite loud audio signal.

The diaphragm of the LCD-4 is very thin, and an over-pressure, which might happen as you don and doff the headphones, could deform and/or degrade diaphragm performance. To combat this, Audeze has added this felt ring to provide pressure relief for the diaphragm. But, to my eyes, it seems there may be other advantages.

In all measurements I've made of LCD-2/3/X headphones in the past, I see evidence of "pad bounce" somewhere between 30Hz and 80Hz. This appears as a gentle wiggle in frequency response, below which response begins to fall off. This "pad bounce" is essentially the resonant frequency of the elasticity of the ear pad and enclosed air. This phenomenon can also be seen with some headphones (not LCD as frequency may be too low to observe) in the isolation curve as outside sound stimulates the resonance and actually provides a modest gain, rather than loss, of outside sound heard. Measurements of the LCD-4 show no evidence at all of pad bounce!

Though there may be other reasons—like changes in pad foam or cover material—it seems to me quite logical that this felt damping ring may spoil the Q of the pad/enclosure system and reduce this very low frequency resonance.

A byproduct of this reduction in Q might be better bass extension. My measurements do quite clearly show excellent bass extension in the LCD-4. In an email correspondance, Dr. Drag Colich, CTO of Audeze (commonly known as "Doc C."), said it was not too much of a stretch to call this an "aperiodic vent", but that it's not working in quite the same way it does with speakers—where it is used to spoil the Q of a speaker enclosure. He did, however, say that the much improved bass extension was primarily due to the increased compliance of the very thin diaphragm, which lowers the primary driver resonance and allows for larger diaphragm excursion. He has driver measurements showing the 3dB down point in the bass at around 5Hz!

Okay, maybe it's not an aperiodic vent, but I like the idea and couldn't resist throwing it out to Audeze and hearing what they had to say. For more info on what the heck an aperiodic vent is, go here, here, or here.

Fine Tuning Process - All of the above information is rather course when compared to the actual work of tweaking and tuning headphone performance. Sankar told me their process is usually done in three stages: Optimizing magnetic structure to create the most uniform flux density possible; optimizing diaphragm circuit traces to produce the most evenly distributed motive force across the surface of the diaphragm; and lastly, optimizing the acoustics around the driver for best performance—which was usually expressed to me as best impulse response performance.

In confidence, Sankar showed me a few very interesting finite element modeling results investigating diaphragm Eigenmodes and how to reduce them. The results were pretty darn spectacular. He said they spent many, many, many hours making small tweaks to various geometries within the driver, each time iterating through the modeling. By the sound of it, no part was left un-tweaked in one way or another.

I did walk away with one important impression, however: The so-called "Ortho Wall" (thin, high-Q resonance ridges seen in cumulative spectral decay plots of most all planar magnetic headphones) is very likely due to diaphragm Eigenmodes. As much as we might like to think these diaphragms are moving like well behaved pistons, they're not.

Summarizing the Engineering Detail
I must say I deeply enjoyed the dialog with Audeze surrounding my LCD-4 review. It focussed more on principle than the particular product. I came away impressed yet again with Audeze's campaign to command a leading position in research and development in planar magnetic headphones.

The dialog had a secondary pay-off, this one accruing to InnerFidelity readers. My badgering for information over the last week has resulted in the completion of a tidy little white paper done by the driver design team at Audeze describing in some detail—graphs and colorful flux density simulation cross-sections included—the magnetic structure of the Fluxor in the LCD-4 compared with other designs. You can pick it up here.

And now, onto the important bit: How is the sound quality of the LCD-4?

COMPANY INFO
Audeze LLC.
1559 Sunland Lane
Costa Mesa, CA 92626
support@audeze.com
(714) 581-8010
ARTICLE CONTENTS

COMMENTS
ADU's picture

Thanks for yet another great review, Tyll. Couple questions...

Could the imbalances in the LCD-4's treble be corected with some EQ-ing? And is the laid-back response in the mid-treble more of an aesthetic choice, or a technical limitation of the Audeze designs in your opinion?

The technology in these headphones is (to borrow a phrase from Mr. Spock) fascinating! Lookin forward to the SINE review as well.

Tyll Hertsens's picture
...in my rush to meet my personal deadline, I forgot to include my EQ profile. I shall fix this and update the article tomorrow.
ADU's picture

Seeing the EQ adjustments is very helpful.

Can you measure a headphone's FR after an EQ function has been applied to see how it effects the response curve?

tony's picture

Geez, we used to say things like this about the Magnaplaners that we loved so much. Magnapan even went to ribbon technology to solve things.

I liked all the Audeze I tried ( except the 8 Open that I impulse bought ) but they are wayyy too heavy for me. These 4 versions only need 1 milliwatt so no problem driving them.

Planers can be Devine and Wonderful as long as a person isn't too fussy yet Bob Katz seems to be enamored with the OPPO type.

Your elaborate description of these 4 transducers is very similar to what Dave Wilson says in describing all Planers.

I've owned and sold every type of Transducer device, I'm a Dynamic driver believer as a result. Nothing is perfect but dynamic's 'end-cost' is usually about one third.

I have to say that Planers have tons more "Sales-Sizzle" than most other types making them easier to sell to the "Ultimate" type of Audiophile.

Recorded Music moves the needle more than subtly improved headphone performance, ( from my point of view ). I just got in some Mercury Living Presence recordings from the 1950s and 1960s which are superb. Simon Trpceski just performed the Lizst Piano Concerto 2 with the Detroit Symphony, a recorded performance, it is also superb.

I'm chasing well done Recordings now.

Great Reviewing from Montana, again.

Tony in Michigan

ps. Audeze owners will like that fancy hard Case when they show-off their stuff at the Meets.

Jazz Casual's picture

Interesting read as usual thanks Tyll. I've auditioned the LCD-4 and liked what I heard very much overall. However, I did think that the treble sounded "hi fi" in the sense that it seemed accentuated in a way that made it sound a bit artificial. That's just a minor criticism of the first Audeze headphone that didn't sound veiled and closed-in to me. It combined saturation with clarity if that makes sense, and I preferred it to the HD800S which like the HD800, remains an uninvolving listen for me.

dan.gheorghe's picture

Indeed. Actually I think they are very clean, transparent sounding offering excellent clarity. Also I do find them often more involving and tactile than HD800.

dan.gheorghe's picture

Very informative and thorough review. Thank you for your time.

I have a review unit for almost 3 weeks already. While they might not be the most linear and detailed in the treble and upper midrange, I found them extremely potent in the rest.

For me, they offer the most real life like experience I've heard in a headphone. The bass and midrange section is the best I've ever heard.

Beside that, the transients are explosive, fast and natural to my ears. The LCD-4 hit hard on every note and have a very tactile presentation.

I cannot use dull near LCD-4 because of that, especially when compared to the soft HEK which I personally consider dull because of that very reason.

I would use another term instead of "dull" for LCD-4 which is often heard under amped and thought to be dull (soft sounding) because of that reason.

Beagle's picture

Tyll, is it possible that the excess energy above 10kHz is helping to provide the clarity and articulation in the bass and midrange? And if it were to be eliminated, might the bass and mids revert back to 'LCD-X/3 territory'?

I mention this because it is quite common for mixing engineers to boost the upper treble (10k to 14k) to eliminate murk and "clean things up" in the lower ranges of recordings.

Again, I mention this only because, like EQ itself, there always seems to be trade-offs in headphone voicing.

Tyll Hertsens's picture
I think it doesn't work quite that way on this headphone because there's so much clarity despite the uneven treble response. I think the LCD-X works kind of as you said, but because the frequency response anomaly is somewhat masked by low level distortion from diaphragm resonances so the elevated top octave can act as a proxy for the missing 4-8kHz. With the LCD-4 there's so much right going on, the the treble anomaly sticks out as a problem more clearly.
ericg's picture

Hi Tyll, i really enjoyed your article but one thing struck me as an understandable mistake here. The use of the word -symbol- where you must have meant -cymbal-. Otherwise excellent piece!

Tyll Hertsens's picture
Damn rogue lysdexic brain cells. Thanks for pointing it out. Fxt.
mithrandir39's picture

I know you like and respect Audeze, so writing a mixed review like that can't be too much fun. But I really respect your integrity in telling it like it is. I spoke to Sankar at Canjam last weekend, and he said these are selling like hotcakes-and I told him I still preferred the 2 and 3 overall. On a side-note, I love the headbands! Very comfortable and they distribute the weight much better. They should come standard on all the LCD models.

Tyll Hertsens's picture
....and your right, it's not any fun at all.
moopster's picture

Tyll, thanks for your review, I like how you can turn a phrase, "You can knock a tooth out with this headphone." My perception of the strengths of this headphone mirrors yours quite closely. One of the things I found most interesting in your review is that your perception of cymbals on this headphone is the polar opposite of mine. I find cymbals to sound particularly engaging, natural and lively, so much so that I seek out music with lots of cymbal work. As the drumstick impacts the cymbal I hear a nearly instant attack, the bell-like ting of the metal simultaneous with the wooden click of the stick, followed closely by a shimmering sizzle that fades with even, linear decay. I have one of the early, 100-Ohm versions of the LCD-4, I wonder if that's where the difference is. Could be personal preference, too, as in Bob Katz saying the LCD-4 "sound just about right without any EQ at all" and not liking the HE-1000. At any rate, I enjoy the LCD-4 immensely, the fast response makes other phones sound dull and artificial.

ar's picture

I was gonna mention that too...

I heard the early version of the LCD-4 and the thing that struck me was that it didn't have the mids missing, like LCD3, and how much of an improvement 4 was.

I suspect it's the difference between the 100 and 200 Ohm version as well.

May be worth to check it out, Tyll.

Laurence Wayne's picture

Hey Tyll- Just a comment and a heresy or two. Having met Sankar and after several conversations with him and Dr. C, I just want to add "true gentlemen" to the their scholar description. They were both cordial and responsive at all times. There is no doubt that they desire to create the finest headphone experience possible. And now the heresies-even though I know your predilections on both issues:
After 70 hours of break-in on my LCD-4 I noticed a definitive smoothing out in the frequency range you mentioned-and I agree with your assessment until that time.
And, although the stock cable was fine, switching to Cardas Clear definitely widened the sound stage and added a bit of detail overall as well.
I am thoroughly enjoying the superb musical experience (and the comfort of the new headband) provided by Audeze LCD-4.
Judge Laurence Wayne

logscool's picture

I know in the past you have said that you have all of the data in your current measurements to create CSD's and now I hear you saying that you think the visual readability is drool worthy. Does this mean we will soon be seeing innerfidelity CSD's?

Tyll Hertsens's picture
..but someday.
tony's picture

Do you suggest Customer Service Desk

or

Cat Scratching Disorder ?

Google has 138 meanings for CSD

Tony in Michigan

Tyll Hertsens's picture
Cumulative spectral decay plot.
tony's picture

Hmm, sounds like something I've got, I'll ask my Cardiologist next time around.

Thanks for explaining!

Funny how Audio stuff can have this, spectrum seems like a Visual description as in degrees Kelvin or wavelength.

By the way, I met a drummer that claims that it's been impossible to properly record cymbals ( and maybe even symbols ) because the microphones and electronics can't handle the intense dynamic range. I wonder what the "K"-Man has to say about it? Anyway, drums are recording engineering problems, maybe we shouldn't expect too much .

Thanks for responding,

Tony in Michigan

zobel's picture

Some hearing loss is normal for those of us with some years on our ears. You could call it cumulative loss, but we're not decaying yet (I hope).
Yep, recording the full dynamic range of most percussion instruments is problematic, since the average overall recorded level has to be so low to keep the peaks clean. Lots of dynamic compression is often used on cymbals and drums, along with physical damping of the instruments in the studio. I'm a drummer with a recording studio in home, so I always run into this issue.

I think you are wise, with the gear you already have, to looking for recordings now, and new tunes, with your audio bucks. After all, that's what its all about to begin with, right?

Be well,
zobel

tony's picture

Hello Mr.Zobel,

Again, it's nice hearing from y'all.

Music is my important pursuit but I suspect that quite a few have gear as their "most important", god bless em, plenty of outfits are eager to build $5,000 solutions to what seems to me to be a $500 problem ( they manage to sell their stuff to their loyal following ).

Our Nation is on a Technological tear, just now. I'm seeing Furnace Manufacturers making 98% efficient furnaces for the typical home ( the darn things also heat the water ), LED lighting for residential applications is now a reality ( great efficiencies easily within reach ), self-driving 50mpg Cars are about one decade away ( expect a 30 year service life on these ), politically we have a "Socialist" tearing up the "Field" and a Woman running for President, Phew! ( and that's after we had a Black President for 8 Years ).

It all started with Ben Franklin and the Lightning Rod, about 250 years ago.

Our headphone success began with the iPod and iTunes ( I think ), was that only 10 years ago? Back then I owned the Stax Earspeakers for headphones ( which were too fussy for me ).
My headphones haven't gotten better but the Amps have, ( I love my Asgard 2 ).

If my Bernie does well at the Convention I'll finally get to see Montana ( once or twice ) I hope to get out and about for a bit of bicycle riding in Billings and that other town ( are there more than 2 ? ), maybe I'll get to stop in and see TTVJ & his $10,000 record player ( betcha he makes me buy one of his Amps ).

Tony on the Road again

zobel's picture

Tony, King of the the Road;

Didn't headphone success start with Sennheiser HD 414? I still have mine. First open headphones, not much bass, smooth mids and soft treble. Still the best selling headphone to date, with over 10 million sold. 1968. >>FF 2016. Now...HD414 don't hold a candle to anything. 48 years has seen great improvements in headphones, but like you said, so much more in recordings.

You're better off riding your bike in three forks, home of TTVJ, than in Billings, IMO. I don't know about that other town you almost mentioned.

If you visit Montana, it is good to know the two things important to us here:

1) Don't sweat the petty things
2) Don't pet the sweaty things

That is all you will need to get by here.

Be Happy
zobel

johnjen's picture

Dam fine write up…
I can read the disappointment between the lines…
And so close, yet, not quite there, just yet.

At least for 4K$ it has moved the SotA up a notch, which is always a good thing.

I wonder if EQ could 'compensate' for the top end's misdeeds.

JJ

ADU's picture
Quote:

I wonder if EQ could 'compensate' for the top end's misdeeds.

I wondered the same thing. The revisions on page 2 pretty much answer this question...

http://www.innerfidelity.com/content/technologically-impressive-lcd-4-pl...

wbh's picture

Wow!
A year ago, there was that $$ burglary at the Audeze Calif HQ. Huge set back #1.
And now, almost a year later, the same pathetic company gets it's top-end model shot down by none less than Tyll the Mack-daddy of IF.
Methinks the SINE will get a better review with WoF status. That's the way the review-journalism engine works for main-streamers like Stereophile/TEN.
Not sure what the political/marketing strategy is for these smaller niche headphone manufs.
Maybe v2 of the LCD-4 will remedy Tyll's gripes. But it took even Sennheiser almost 9yrs to officially fix the 800.
C'mon Audeze ... you can do it 9 weeks!

ADU's picture

I haven't heard any of the Audeze headphones, so can't really comment on the pros/cons of their treble response. But all of the LCDs seem to be a little laid back in the mid-treble on the FR graphs (and perhaps also a little aggressive in the upper treble).

I wonder if that's how Audeze wants them to sound though. Or if the treble will "even out" with time/usage as someone else suggested.

Jim Tavegia's picture

I have a number of cans and even the Focal Spirit Pros from your review pushed me that way. But I thought they were pretty dull sounding, but that is MY problem with hearing loss over 6K due to my age a Mary firing range damage.

I believe that bob Katz has been right on about find a great set of cans you like, but be prepared to EQ based on what EACH OF US HEARS AND OUR HEARING PARAMETERS and stop thinking that if you have to EQ it is a bad thing as it is not.

I continued to work on EQing my Focals and now really like them. It amy take some time or not much at all depending up one's taste, but doing this really softened the blow from spending $350 on a pair of cans I was not going to use as much, but now I do.

In my home studio I don't use them for tracking, but for mix downs and general listening I use them as much and now use my AKG K701s for my high res usb computer dac listening.

You site has been a great read and those of us who listen in cans a lot have learned so much from you. I also agree that your assessment of buy the right headphones first, agonize over your source components, and then the amp. You have to start at the front and work back to get the most out of your listening experience, just like, to me, speakers are the most important part.

sunnydaler's picture

I'm waiting for your review of Audeze SINE. I like their smooth and resolving nature but think they take some edge off distortion guitars in rock music and tame the atmosphere a bit.

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