HD800 and HD800S distortion analysis

Discussion in 'Headphone Measurements' started by purr1n, Jan 17, 2018.

  1. purr1n

    purr1n Finding his inner redneck

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    I don't remember what Tyll wrote exactly, but I did get the sense that some people (you know, the type that tend to be really keen on minor stuff, like many of us here) who heard the HD800S early on thought the bass gave us a warmer and more fuzzy feeling than the HD800. For most listeners, the differences in the bass are insignficant. But when people like me are splitting hairs on DACs, such a change may not necessarily be welcome*. SBAF being SBAF, or Tyll being Tyll, probably wanted to peak into the measurements to see what was going that might explain what we were hearing. How this became a measurement war, or a measurements-for-the-sake-of-measurements thing, I scratch my head. My question to Jude is what does he hear?

    * My position remains that if one is willing the mod the HD800, then the HD800 is preferable to the HD800S, especially given the price premium of the HD800S over the HD800.
     
    Last edited: Jan 23, 2018
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  2. Serious

    Serious Inquisitive Frequency Response Plot

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    I know, measurement-war and all, but two things I noticed in the measurements:
    • On the EARS coupler the HD800S seemed to get better bass extension. I think Sennheiser mainly wanted to improve the extension and the added distortion is simply the price to be paid. We also have to remember that as Bill-P showed earlier, Sennheiser changed the pad design of the HD800, which probably gives us slightly less bass extension than Tyll's initial HD800 measurements from way back in 2009 show. So comparing the 2009 IF HD800 to the 2017 HD800S measurements is probably not fair in this regard. My own HD800 vs HD800S measurements on the same coupler also showed slightly better bass extension from the HD800S. Subjectively that also seemed to be the case, although it's been a long time that I've heard an HD800S and I'm generally not a fan of the HD800S. (Then again I'm not sure if this is the Bill modded HD800, which might not get the same bass extension as the regular HD800.)
    • Marv's distortion plots here do show less of an upper mid/lower treble 2nd order distortion spike on the HD800S. Although I've never measured such a spike (at least not nearly to the same magnitude) and my understanding is the FR on the coupler may be responsible for the apparent distortion here. Whatever it is, the HD800S measures better in this regard as well. It's possible Sennheiser tweaked something for that, too.
    Again, I'm not much of a fan of the HD800S myself, but these two things do point to me that Sennheiser changed and arguably improved some things relative to the HD800 other than the resonator.
     
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  3. james444

    james444 Mad IEM modding wizard level 99

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    Thanks for your time and effort to investigate this in-depth! Your results are consistent with all others I've seen, except Jude's. At this point, I tend to think there's something about his new rig that makes it produce different results from the rest, and I'd really love to see him take some comparative measurements between his new and old rig (provided he still has the latter).

    Like with the "mysteriously absent" 10kHz spike in his MDR-Z1R and IE800S measurements, it might not be that hard to find a likely explanation for this discrepancies, if only he were willing to investigate things further on his side. I doubt it will happen though, since he seems absolutely convinced that his results are the only valid ones.

    Speaking of which, I've found Heinz Renner's (the AKG K1000 developer's) HD800 vs. HD800S comparison on a German forum and it too shows slightly higher bass distortion for the HD800S. Yet another DIYer with subpar rig, obviously.
     
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  4. Kunlun

    Kunlun cat-alyzes cat-aclysmic cat-erwauling - Friend

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    Well, Jude, I'd like to invite you to respond here. I'm sure Marv would be happy to help you if you don't have a handle here yet.
     
  5. Klasse

    Klasse Friend

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    @Marvey what can you tell about the earpads? Do they look or feel any different? (stock HD800 vs stock HD800S)

    The earpads on my HD800S feel somehow crispy and I've never noticed such a thing on my former HD800.
    Sadly I don't have the HD800 anymore to compare properly.

    Gently pressing the external (more cushioned part of) the earpads on my HD800S is not perfectly silent.
    A slight crunchiness can be heard and felt.

    [​IMG]

    On a side note (not sure if already mentioned) the 3 units of HD800S measured by Tyll provided slightly better isolation in the treble region relative to the HD800 and HD800SDR he also measured. It's only 2-3dB difference overall over 2kHz (including HD800SDR) so maybe not relevant enough, although a slight tweak on the earpads can lead to that sort of difference.

    Thanks in advance!
     
    Last edited: Jan 25, 2018
  6. Besnia

    Besnia Almost "Made"

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    Interesting. Directly comparing 800 vs 800S, it seems to me the bass does sound just a tad more "vintage/tubey" on the 800S but it does rumble a tiny bit more. However, I wouldn't call either bloated. Imo both 800 and 800S have compressed bass, especially when compared to the higher end Focals. A good bass should sound like it's attached to a spring, if that makes any sense. The HD800(S) do the job well up to moderate listening levels. The harder they get pushed, the more compressed the bass gets, but never bloated. It seems too many audio hobbyists get easily swayed by measurements and charts :)
     
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  7. NightPhotographer

    NightPhotographer Rando

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    @purr1n Thank for referring me to this thread. Do you have any idea how Sennheiser has added passive 2nd order harmonic distortion? I understand how it's added in tube amps by I cannot understand how Sennheiser did it. Did you ever EQed HD800S? Does the bass become even looser when bumped up?
     
  8. BentFlowers

    BentFlowers Rando

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    Thank you for the varied measurements @purr1n . I wonder how close you are to damage by over-excursion with the high level measurements? Could that level have damaged the HD800 S to the point of altering the distortion characteristic? I wonder partly because u/oratory1990 on Reddit also found the lower third order distortion in the HD800 S, while this is not present in your final measurements. Although If I am reading your graphs correctly, it appears the EARS never measured higher 3rd order in the HD800.
     
  9. purr1n

    purr1n Finding his inner redneck

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    No. Damaged drivers will show significant distortion or massively reduced sensitivity. Note that even at the highest levels, we are seeing only approximately 3% THD and no signs of clipping. We aren't near damaging the drivers.

    Yes, with EARS, we did not get higher 3rd order on the HD800.

    Keep in mind that Tyll and I presented these because we felt that subjectively, the HD800S bass sounding thicker and warmer than HD800 bass. Whether we want to consider Jude's, Tyll's, or my measurements authoritative or not, it doesn't change our subjective opinions of the HD800S' bass quality. Note that there are many others who prefer the HD800 bass over the HD800S.

    Finally keep mind that the crux of the distortion argument was that the HD800S exhibited higher 2nd order than 3rd order compared to HD800 which exhibited lower much lower 2nd order to 3rd order. Let's not forget the forest for the trees!

    In that respect, Oratory's results were consistent with Tyll's and my distortion measurements.

    https://m.imgur.com/3HX9yM2
     
    Last edited: Jul 30, 2019
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  10. Ash1412

    Ash1412 Friend

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    Beyond just a simple distortion measurement, I think we should examine physical differences that would lead to this. I saw this article :https://audioprimate.blog/2017/07/20/canjam-london-2017-meeting-new-friends-and-sharing-sound/ where this is said: "Axel Grell fielded questions about the differences between the HD600 and the HD650. The drivers are the same, the housing is different, with the HD650 having a more closed presentation". This could imply the mesh is denser on the 650, causing it to both be less resonant and boosting bass more at the cost of some extra distortion.

    By itself, this wouldn't have any correlation with HD800S/HD800 differences until we go back to the 1st page of the thread where @sorrodje suspected the same happened to HD800S. And some aspects of measurements also reflect that: maybe HD800S's resonator doesn't actually have more 6k suppression than the SDR (thinking about it: wouldn't the resonator only affect the sounds that pass through the hole on its way to the ear a.k.a the ringing of the drivers back mesh?) but the denser outer mesh rings a bit less, HD800S also has slightly more sub-bass than HD800, only by 3db or something but definitely repeatable from Tyll's IF measurements. We might be able to verify this if someone has both headphones and a loupe/macro lens of some sort.
     
    Last edited: Jul 30, 2019
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  11. Serious

    Serious Inquisitive Frequency Response Plot

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    This is not true. We have measurements on this site that confirm that HD650 and HD600 drivers are different. Putting an HD600 driver in an HD650 enclosure does not make it an HD650.

    The resonator affects the sound in the whole earcup. Also in my measurements the HD800S does have much less 6kHz than the HD800 with SD resonator, but I also think a narrow 6kHz resonator is the wrong way to tame the treble in the HD800.

    Axel Grell also personally told me that there are differences between the HD800 and HD800S drivers outside of the resonator. We can only guess as to what they are, but I know Bill-P even suspects that the diaphragm is different. Note that the impedance is slightly different.
     
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  12. Ash1412

    Ash1412 Friend

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    Yep HD650 has lower Q impedance peak versus HD600 and the same is true for HD800S versus HD800, as fall as I could tell from IF's data. Could be a modification to excursion to accommodate the slightly more sealed enclosure.

    I also think fixing a not-so-great enclosure/mesh baffle design using a resonator is kind of, um, cheap but Sennheiser's always been about modularity and replaceability so they probably won't do a whole redesign of the enclosure. Well, we did get the closed version which doesn't have a 6k peak but it seems to mess up other areas in an even worse way. Too bad they patented ring drivers in headphones and Grell's gone so now its all up to the modding community.

    Thinking of modularity, there are HD800S drivers for sale online : https://www.audiosanctuary.co.uk/official-sennheiser-hd800-replacement-ear-capsule-each-clone.html. There's even a driver transplant service. If one could get ahold of one of these and measure them that would reveal a lot.
     
  13. BentFlowers

    BentFlowers Rando

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    On the first page, you mentioned clipping: "The very high SPL 39Hz tone might be pushing the driver so hard to clipping that it doesn't near matter."

    Are we talking two different definitions of clipping here?
     
  14. purr1n

    purr1n Finding his inner redneck

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    We are talking about context and explanation of why the HD800 and HD800S measurements started to look alike at higher SPL. The word used should not have been "to" but "toward". Note that at no point, I ever hit x-max. And even if I did, it wouldn't damage the driver unless the signal is sustained. I've easily hit x-max on Focal, HD650, Grado, and RAAL drivers running 30Hz signals :)
     
    Last edited: Jul 30, 2019
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  15. purr1n

    purr1n Finding his inner redneck

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    Here's not quite an equivalent comparison, but it shows similar behavior between Oratory, Tyll's, and my results. Note that Oratory uses a 20Hz signal, Tyll and I are using 39Hz. I might be driving the HD800 10db higher. I think there is enough objective data and subjective impressions to conclude that the HD800S' bass has different characteristics than the HD800, notwithstanding Jude's results and ears. It is also entirely possible that Jude's HD800/Ss were different.

    Oratory
    [​IMG]

    YEL = HD800
    RED = HD800S
    [​IMG]

    Tyll
    RED = HD800
    BLU = HD800S
    [​IMG]
     
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