Sennheiser HD 800 S: Tweaked and Delightful...and a French DIY Response

Sennheiser HD 800 (left) and newly evolved HD 800 S (right).

Sennheiser HD 800 S ($1699)
When introduced in 2009, the Sennheiser HD 800 rapidly became recognized as one of the world's best headphones, having unbelievably good transient response and detail retrieval, spectacular imaging, and being competitive with the best electrostatics and planar magnetics—having some trade-offs here and there.

But the HD 800 is also quite problematic. It has a sharp sounding peak at around 6kHz that will, at times and with problematic recordings, drill a bleeding hole in your eardrums. Adding to this problem is an overall cool response, lacking the bass extension that, say, an Audeze LCD planar magnetic can has.

I'm not going to do a traditional InnerFidelity headphone review here; the new HD 800 S is very much like its predecessor only changing a few small acoustic tweaks, and being dressed in a black livery—a look I like very much. So, if you want to read about styling, comfort, and build quality—all of which are terrific—you can look at my previous HD 800 review here and just imagine it in black. Oh, and with two cables: one with standard 1/4" plug; and the other with a 4-pin XLR for balanced use.

In this article, I'm going to bring out exactly what I've found as the acoustic differences between the HD 800 and HD 800 S. And! I'm going to tell you about a very cool modification you can do to an old HD 800 to get some of the benefits found in the new HD 800 S. Grab a cuppa, sit back, and enjoy, I promise this will be an interesting read.

Acoustic Changes to the HD 800 S
Sennheiser, from what I can tell, has done two things to the HD 800 S to improve its sound quality: Damped the spike in response at 6kHz, and warmed up the headphone a bit. We'll take them one at a time.

Killing the 6kHz Spike
Right after I published my HD 800 review, I also published what was termed at the time "The Anaxilus Mod", which intended to damp the 6kHz spike by putting felt in certain positions in the earcup of the HD 800 to reduce its ability to resonate. This mod has evolved over time and it seems lives on in this SBAF thread.

The problem with adding a bunch of damping material in the ear cup is that it's not particularly selective about what frequencies get attenuated. If the problem at 6kHz is narrow-band, well, using a solution that's narrow-band makes more sense than wide-bandwidth absorbing material.


Current SuperBAF mod using a specific rug liner material to damp the earcup.

I need to note here that the materials now being recommended by HD 800 modders at this point are not simply wide-band absorbing felt. Many, many materials have been tried and measured. The current material of choice is somewhat elastic and has regularly repeating holes (see photo above)—both of these characteristic may give the material a degree of selectivity in what frequencies are attenuated, and may also be a source of spurious secondary emission of sound.

Sennheiser, being the smarty-pants engineers they are—and I say that with a great deal of affection—took the alternate route of engineering what, it seems to me, is a narrow-band Helmhotz resonator into the opening at the center of the driver. Essentially a surgical attack, providing a tightly tuned anti-resonance at 6kHz.

Helmhotz resonators have been around since 1850 when Hermann von Helmholtz exhaled a sharp sigh of relief after finishing a bottle of poor brew and heard the bottle emit a tone...Ha! No, sorry, I have no idea how he figured it out.


He invented these cool looking resonators, and observed that if you stuck the bottle neck and hole into your ears, the resonator would amplify the frequencies near the resonators natural resonance and damp other frequencies. He went on to make a variety of sizes of the resonators and, when presented with a sound, each bottle would resonate with certain ranges of the sound presented. Measuring the amount of sound resonating in each bottle would permit a crude method for measuring the spectral frequency content of the sound. Amazingly, this was one of the first audio frequency response measurement system. Here's the Wiki for Helmhotz Resonance.

I was fascinated to learn that one of the most common modern uses of Helmholtz resonators are in engine exhaust systems. Resonators are built into the muffler and tune the "exhaust note" of the system. Want to bring out the growl of a V8? Tune it with a resonator. But it's also important to know that you can use these resonators to tune out a frequency. Want your Benz to whoosh silently down the road? Tune out the noise with resonators.

Basically, if you use the right resonator in the right place it can be anti-resonant with the tone of interest. Imagine the sine wave of an audio signal of a particular frequency of interest passing by the opening of the resonator. At the top of the sine wave, high pressure enters the bottle, which then bounces of the inside of the bottle at the resonant frequency, and the high pressure returns to the opening of the bottle one half wavelength later. Well, the original sound is now one half wavelength from its previous maximum and is now at the low point of the sine wave. So, you now have the low point of the sine wave meeting the high point of the wave as it exits the bottle delayed by a half wavelength, and the two cancel. In other words: Helmholtz resonators can be used either to amplify or cancel particular frequencies.

The new HD 800 S has, as far as I can tell, a Helmholtz resonator—or something very much like it; there are variations on this theme like 1/4 and 1/2 wave resonators—built right into the center opening of the driver on the inside of the headphones. And this resonator, from what I can tell through measurements, is anti-resonant to the 6kHz spike generated by the acoustics of the earcup enclosure. Measurements show that the HD 800 S does precisely damp the problem.


In the photo above, I'm shining a flashlight in through the back of an HD 800 S. There's a fine screen mesh over the entire front of the driver up to the screwed down metal ring. This mesh has a small donut of air impermeable material partially closing the space behind it in the central hole. You can equate this to the neck and opening of the resonator. In the bottom of the well there's a mesh screen that looks identical to the HD 800 from the outside, but as I closely inspected it, it does seem that there's an additional layer of screen at the bottom of the hole on the inside. I think this screen may act as the bottom of the closed bottle, but does allow some air to pass slightly diminishing the amplitude of resonance for a given input. I think controlling the permeability of this layer at the bottom is used by the engineers at Sennheiser to adjust the damping to the right level. Caution: A lot of guesswork going on here.

The important thing to note is that the enclosed chamber of this resonator is completely empty...just like the beer bottle you can blow across. If you put damping material—like the batting inside speakers—into the bottle, it would become much harder to get a clear tone out of the bottle. The damping material would "spoil the Q" (damping the ringing bell-like quality) of the resonator. So, a surgical strike on the peak at 6kHz by the Sennheiser engineers. Well done!

Warming the HD 800 S
No onto a bit tougher problem: Making the HD 800 S a little warmer and more inviting—even with the fix to the 6kHz spike the headphone remains a bit cool. This is really tough to fix for an open acoustic design. With sealed headphones you can use the sealed chamber of the ear cup to contain the pressure of the long low-note wavelengths and boost the bass some. With open headphones, the driver usually has a primary resonance between 60 and 150Hz (it's about 110Hz on the HD 800), below the primary driver resonance, driver efficiency will evermore reduce as frequency lowers. The result is loss of low frequency extension. Bottom line: there's not much Sennheiser can do to increase bass response of the HD 800.

But! There's a little trick you can do to increase perceived bass response in low frequency limited devices: Add second harmonic distortion to the low notes to "bloom" them up a bit. This is often done in the Bluetooth portable speakers, which, due to their small drivers and overall small size, have problems reaching way down into the bass. By selectively adding 2nd harmonic overtones to the low notes, overall bass energy is increased—albeit at a higher frequency than the original tone—and your perception will be a euphonic warming of the bass. It's euphonic because the second harmonic is exactly an octave above the primary tone, so it remains in harmony with the original music. On the other hand, it is a distortion, and those with well trained ears will hear the bass as slightly less precise and authoritative.


The plot above shows the spectra content of an HD 800 S and HD 800 reproducing a 40Hz sine wave. As you can see, the second harmonic at 80Hz has 20dB more amplitude than the 2nd harmonic of the HD 800. The third harmonic at 120Hz is about the same; the fourth harmonic at 160Hz is about 3dB louder on the HD 800 S.

Editor's Note: When I first saw an increase in distortion of the HD 800 S over the HD 800, I wanted to make sure it wasn't just a problem with the one HD 800 S I had at hand. Neither Todd the Vinyl Junkie nor HeadRoom had any left, the U.S. PR rep had none either. I immediately went over to and asked for some help. Members TMoney and Dr. Higgs volunteered their new HD 800 S headphones, which I arranged to have shipped overnight. Upon receipt I did repeat my measurements and found these headphones to perform essentially identically to the pair I initially tested. My experience is that Sennheiser has great quality control with unit to unit variation being very low...but I did triple check, and my measurements for all three were very similar.

The first observation I'd like to make here is that there's a thought in audio that the best sounding gear should have a nice, asymptotically reducing level of the harmonic series. In other words: The level of the harmonics should reduce smoothly with each subsequent harmonic being lower than its predecessor. You can see in the plot above that the level of the second and third harmonics are are roughly the same on the HD 800, which, according to this rule, would not be optimal. With the HD 800 S the second, third, and fourth harmonics are ever smaller. This might indeed be a preferable tuning. I do have to note that the fifth harmonic at 200Hz is higher than the fourth in both headphones; this may not be desirable, but it also may be one of those things that Sennheiser engineers likely can't adress without screwing up something more audible. It's 60dB down from the fundamental tone, so it's likely not an audible problem.

And now, the big question...

HD 800 S Sound Quality
For me, the HD 800 S delivers a markedly more pleasant listening experience than the HD 800. The piercing treble problem has been reduced to insignificance and replaced by a marvelously articulate and responsive presentation of the treble. And the overall tonality of the HD 800 S is indeed noticeably warmer and more inviting; the bass is more present in the mix.

But, I do hear the bass as a little less precise in the HD 800 S, having a bit more pleasant bloom, but also being just a tad growly and congested, calling attention to itself. Please understand that I use "just a tad" very specifically here; these headphones don't have noticeably distorted bass; it's just noticeably warm and inviting, but less clear and pure than the HD 800. On the other hand, the HD 800 bass level is a bit too low, and the headphones are cooler sounding than I would prefer.

So, did Sennheiser make a good decision trading off a little added distortion for better tonality? Yes, you bet, I'd much prefer to listen to the new HD 800 S over the stock HD 800. Much. This is where small objective differences can make disproportionately large subjective improvements. I find the new HD 800 S much easier on the ears....musical even, but with clarity taking a front seat over euphony, which seems unusual and very cool to me.

My last note on HD 800 S sound quality is something that has persisted in both the new and original model. The upper-mid-range is a bit withdrawn causing voices to loose some of their natural overtones making them seem a bit more distant. Though I need less bass and treble adjustments when I EQ the HD 800 S, I find I still need a bit of boost centered around 1kHz.

Speaking of EQ, when I listen to the two headphones EQed, I think I tend to prefer the old HD 800, but it's close. With the HD 800 S I find myself being somewhat cautious about my bass level setting—bringing it up to where I like it does make the distortion a bit more obvious. On the other hand, I can tweak out a notch at 6kHz to try to tame the spike in the old HD 800, but the resonance is still there in the headphones, and if a signal gets hot around 6kHz then you can hear it zinging. Niether are perfect, but I think I prefer having to fiddle with the 6kHz notch a bit based on the music playing rather than not being able to dial the bass up to where I want it without lows becoming a bit too congested. However, if I wasn't using EQ, I'd easily prefer the HD 800 S.


My EQ settings for the HD 800.


My EQ settings for the HD 800S.

There are other options though, if you're willing to take the risk. Let's flip the page and see what the DIYers are doing.

Sennheiser USA
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(860) 434-9190

tony's picture

Music can have a high cost.

Even Beethoven lost-out from high SPLs.

I had a scary time listening to my local DSO playing Mahler's 2nd. hitting a reported 121db. at my "up-front" seat. The two vocalists, ( posisitioned at the front of the stage) reported, in the live broadcast intermission, the sound being thunderous, I concurred. Steve Guttenberg reported the U2 group hitting 130 db levels.

The Guardian Newspaper is reporting the problems AC/DC are having and the stopping of the group's tour.

Tony in Michigan

pavement714's picture

So why did I buy the HE1000 partly based on your recommendation that it is a slightly softer, but overall better headphone than the HD800 if suddenly the HD800 is "The Best Headphone In The World?" When you said that in the video I was like "hmmm...."

Tyll Hertsens's picture
...It's simple: I hadn't heard the HD 800 S when I did the HE1000 review. Worry not, the HE1000 is still a marvelously musical headphone, maybe more so than the HD 800 S, but that would be purely a matter of taste.
tony's picture

At some point, you have to accept responsibility.

Still, you accepted the best advice available, you won, you didn't invest in any of the lesser products.

You could've spent $10,000 on the big Stax ( which I owned ) and a Blue Hawaii Amp, a great many folks consider it the best out there.

You did well! the 1000s are one of the top 5 headphones being made today, maybe even top 4.

Tony in Michigan

zobel's picture

Are you thinking about these HD800S, or are you happy with what you have going now? I know you are a Senn guy, just wondered if you are going to go for it with these?

What are your go-to cans now? still using the Shiit Rag?

Is your gov'ner keeping your water clean where you are? No problem here. I should go out now and bust some ice of the creek, and bring in some more water. Were safe, nothing at all upstream, except that pristine high mountain spring. (Just kidding, we have a well).

tony's picture

Sure, I'm a Sennheiser guy, I could be an AKG or Bayer guy, no problem. I've learned from the Automotive NVH ( noise - vibration - harshness ) guys how to "tune" transducer's performance ( which is not at all difficult as our Tyll just discovered from exploring the 800S ). I've also learned from the Audiologists and Dr.Olive ( Harmon ) and Bob Katz that there is no such thing as perfection ( unless you have "Standards" to compare against, as our Bob Katz owns and uses effectively ).

I think that we're left with finding transducers that feature the "singing" voice we enjoy! I love the Sennheiser voice!, they have the Luciano Pavarotti / Joan Sutherland superlatives that sing to me and are cheap ( compared with spending $2,000,$3,000,$5,000 for fresh, sealed boxes of super headphones ).

I've been learning about various 50mm transducers that can perform beautifully but many have housings and hardware bits that obstruct their potential, the Noonteks as an example. So, I looked at headphone transducers as stand-alone devices. I learned that many can sing beautifully.

Headphones has been a curious thing for me, as a business. I discovered Schiit as a useful example of "Internet" based distribution channel systems.

Now, I'm committed to seeing-thru on a Bernie Sanders promise from which I'll turn to Residential LED Lighting systems and perhaps retirement to a Sunny Winter home in Venice Fla. and Spring/Summer/Fall home in Traverse City Mi. I have two older brothers that are anxious to begin a decade of Adventure with me, I'm itching to "have at it", we'll finally get to "See the USA in our Chevrolet", fingers crossed.

Tony in Michigan

ps. I love all the Sennheisers from RS120s thru to the HD800, my RS wireless get the the most milage ( I've tuned them to approach the sound Quality of the HD600). Sennheisers are glorious.

Amp wise I'm an Asgard 2 man, I do own other amps but none I own are as effortlessly smooth, the Asgard 2 is flawless. A possible would be a Tube roller like the Ember from Garage1217 or Lyr or Bottlehead or Valhalla but I like the Rock Solid Performance of the Asgard2 ( I'd have paid $2,500 for it's performance levels and have paid that much but didn't quite get it ). I've paid far more for 2 Channel Amps that were never as musically capable.

Water problems are "all over" the Country nowadays, Flint's lead poisoning is only the beginning of our view of this problem. We as a Nation will be addressing Water Quality in every State. Average American households use 100 gallons of water per day, per person. Grocery Stores can't keep-up with the needs, yet they all seem to have half an aisle devoted to bottled water. We are nearing crisis levels.

zobel's picture

That is a beautiful place Tony. I was there last summer on a trip to my cousins' cabin just south of Suttons Bay on the lake. I was surprised to see all the fruit and wine there, that far north.

Thanks for the gear talk! I too like the wireless Senns. I put 6 CDs in the changer, hit random and go down to work in my little wood shop wearing those RS 175 RF. They really get the most play through the day.

Adventure on! Life is an adventure, not a packaged tour. And keep the music playing.

LiteJazz53's picture

My compliments on a very detailed and informative review, I enjoyed it so much. One of the reasons I chose the newer HD-800S is because of the furnished (4) pin balanced cable. I kept waiting for some comment on any slight differences or improvements, no matter how slight, when using the balanced cable VS the cable with the 1/4" plug. This is one of the reasons I selected the Sennheiser Headphone amplifier, where I could hopefully pull a bit more out of the HD-800S. Is there any sonic improvements when using the balanced cable with the Sennheiser HDVA 600? Hopefully you might tell me there is a tad more low end punch, so what say you??

24bitbob's picture

Where I live, Australia, the difference in price between the HD800 and the HD800S is around A$1,000, that's about US$750. I need to ask myself whether a tweaked HD800, i.e. the HD800S, is worth the A$2599 over and above the HD800's I currently enjoy through my EQ'd laptop source and Luxman headphone amplifier. It looks to me that the answer is a convincing no.

Sennheiser, it seems to me, has missed an opportunity to come up with a convincing and significant improvement (an HD900 model???), and instead are asking customers to fork up large sums of money for a tweak to improve a flaw in their original design. That might sound harsh, but the sums involved are not trivial, and the improvement offered can be equalled and bettered otherwise for much cheaper.

I had nearly convinced myself that the HD800S would be the 'end game' headphone for me. I think I already own it, it's called the HD800.

cpnet's picture

Thanks for the detailed review Tyll. I've been looking for headphones to use as (bedroom) studio monitors, and am looking most closely at the 800 and 800S. For me, accuracy is more important than something that is "pleasurable" to listen to.

The 800 seems to have an accuracy problem at 6 KHz, but I'm not clear which headphone is more accurate when it comes to bass.

A true/pure sine wave should have no harmonics. Are you using an analog device to generate your test tone (and thus imperfect) sine wave, and does that explain the harmonics, or is the rest of your chain that's introducing the distortion (i.e. a tube amp)?

Did you do a frequency analysis comparison of the test tone directly vs. the output measured from each headphone?

The reason I ask is that, the 800S seems to have a flatter response(?) Is it possible that the 800S is more accurate, and the apparent bass clarity of the older 800 headphones is a psycho-acoustic effect due to an (inaccurate) dip around 80Hz? In other words, is it possible that you're not seeing distortion of the original signal in the 800s, but rather a more accurate representation of the incoming signal?

I presume that the 2nd harmonic boost you've seen isn't dynamically adjusting with a change in the fundamental? Rather compared to the 800, there's a fixed area around 80Hz in the 800s that's always louder regardless of the fundamental?

Tyll Hertsens's picture
The AP tester has both digital and analog generated sine waves; both generators are extremely pure.

No, I don't test the tester very often, but when I have it's distortion products are WAY lower than with a headphone in the loop.

I would say the HD 800 S is more accurate than the HD 800 stock. The little dip around 80 Hz is from "pad bounce"---the resonant frequency of the pad bouncing against the side of your head. I've found this to be relatively inaudible.

The HD 800 S just has more second harmonic distortion according to my measurements.

Magick Man's picture

Well, my new HD800S are on the way. Thanks, I guess... ;) I'll compare them to my HD800 and keep the one I prefer.

Babaluma's picture

Which did you prefer and why? Currently trying to decide which to buy...

Magick Man's picture

Overall I prefer the HD800S, they have much better tonal balance. The HD800 treble peak has always bothered me, and it kept me from using them with all types of music, especially if the music is poorly mastered. Now I don't have to worry about that.

Babaluma's picture

Thanks. I've found a few dealers in Paris, so hopefully gonna be able to A/B them with my own lossless flac files and portable player (Fiio X5).

dapost's picture

Hi Tyll, thanks for the great review! Did you measure distortion of the HD800SD? Sorrodje's measurements indicate that the HD800SD has even greater distortion than the HD800S in most of the audioband, including the sub-100Hz region.

Sorrodje's picture

My Measurements suggest more distorsion indeed but last measurements from Purrin show the same results than Tyll.. I still provide mine cuz I want to be as transparent and honest as I can but if I were you , I'd be more confident in Tyll's and Purrin's than Mine. They're far more experienced and reliable.

My 2 cents.

dapost's picture

Thank you Sorrodje, indeed Purrin's measurements show that your mod does not affect distortion. But I missed Tyll's distortion measurements of the modified HD800. You see, I need to decide in the next few days which one of the two versions to buy new. I think I will go for the original HD800 cause of the distortion issue.

dapost's picture

Apologies, Tyll has indeed measured distrortion of the HD800SD - it's all in the pdf.

natra84's picture

Hi How does this compare to HD700 in the highs

hapnermw's picture

Hi Tyll, Thanks for doing the lord's work for the headphone community. On the issue of EQ, I know you are aware of its phase, etc. issues when done in the analog domain. Have you done any analysis of your use of JRiver/EQuilibrium vs the use of high end DACs. The primary issue is that I would expect similar phase issues with this digital EQ. For instance, I'm using a Schiit YGGDRASIL DAC, if this isn't fed the exact recorded bits, it's value is mostly lost. I would expect that JR/EQ uses the typical Parks-McClellan FIR algorithms that have been responsible for compromised redbook playback for years. Trading a bit more HD800 base for the pre-ringing and the other compromised phase accuracy this results in doesn't seem to be a good tradeoff. What say you ...

emptymt's picture

how does this compare to the ether/ether c in terms of tonality and technicality?

which one is warmest and which one is closest to neutral?

I intend to use them to listen to mainly metal music and other genres are second, which will suit me best?


Babaluma's picture

Which to buy? They will be used mainly for pleasure listening, but also sometimes for audio restoration work and mastering. I currently use HD600. Will 800 or 800S both be a huge step up? Have read both of your excellent revbiews, but am still undecided! Anyone know a shop in Paris that has both I could try, with my Fiio X5?

vijaygt2020's picture

I appreciate your hard work and enthusiasm to help others by sharing your views on the headphones. Thanks again - banquet halls in delhi

adam_glazier's picture

I started selling the SuperDupont Resonartor mod because I needed to make my own and could not figure out how to message Sorrodje on SBAF and didn't want to wait for international shipping.

michab's picture

Hello Tyll,

At this time i have got the akg k712, and i want to step up my headphone game.
at this point i consider the Focal elear, the mr. speakers ether and the hd 800/800S.
i have got a eq system. But i do not want to modify my headphones.
In this video you say that the hd800 with mod and eq is superior to the hd800S.
I wonder if it is still true without a mod. and overall witch headphone you enjoy the most.
Thank you very much.

Headphones's picture

Pretty Good Pair Of Headphones !

Ernie Myers's picture

When I first received my HD800s, I too thought them thin and too bright. I recabled with a Norne Draug and put about 200 hours on them. They have mellowed out and become much warmer with a beautiful treble. With their detail I'm enjoying them more than I ever thought I could enjoy a set of headphones. Still think they are the World's Best Dynamic Headphone.