Background: This is a write-up I did elsewhere about mods I made to my HD6XXs. The mods are based on the KISS approach of removing the rear spider and foam and applying limited damping, preferably with Dynamat or similar. Google KISS for more info.
Spider and foam:
(credit:superbestaudiofriends.org)
Finally took the leap to mod my 6XXs (purchased 2019), with interesting results. I kept it *very* simple:
Order of Events
1. Removed spider and rear foam completely.
2. Stuck some small pieces of SH-21K fo.Q. dampener I had laying around.
Next day:
1. Removed damping, listened with just spider/foam removed.
I ordered the recommended sampler pack of the Second Skin Audio dampener, but figured I'd try the fo. Q until it arrives. Fo. Q is a Japanese company that has been around a while in audiophile circles specializing in damping products made with material developed supported by Japan Science and Technology institute.
The thing with the fo.Q is in the past I've found it to be a little *too* good at vibration damping. I use it sparingly and so I have plenty left over. So I wasn't sure what to expect when I put some on the 6XX magnet.
FYI: I listened with the damping mod first, then with just spider/foam removed the next day - no fo. Q.
Gear: Foobar/ASIO--> USB/SPDIF Converter -->Topping E50 (ES9068AS) --> Asgard 3.
Impressions [w/Damping]: First thing that struck me vs. stock was a bump in the lower and upper treble. The change was so jarring that I instinctively tensed up, expecting the presentation to turn shrill fast. It didn't. Instead what I heard was just...clean. The Egg's 'Fat Boy Goes To The Cinema' is IMO a fun but overly bright track that I now use to test the limits of fatigue while demo'ing gear. Stock, the 6XX suppresses the upper frequencies just enough to make the track listenable on repeat despite the ESS dac, but still has some splashy frizzle at the very top.
With the mod, not only is the treble now prominent, it's devoid of any edginess or tizz that one might expect to come with that. It took me a long while to relax because I kept expecting to flinch from an over bright top end that never came. The Egg track is now the best I've ever heard it through the 6XX.
Next is the bass. Bass performance I found to have more low end slam/impact AND a perceived reduction in the mid bass hump. As if the hump got moved lower. So the low ends sounds more extended. Like the upper frequencies, the bass also sounds cleaner, with improved resolution. More distinct. Not bloated or bleeding into the mids.
Speaking of Mids, the midrange I would say is more or less the same, just not as prominent as stock. Again, like the bass and treble frequences it sounds cleaner than stock, just not as much of a bump up because it was already so good.
All together, the mod sounds amazing.
Impressions [No Damping]: The next day I figured I would be thorough and I reluctantly removed the fo. Q. I wanted to get a sense if the damping had any effect at all. I was also curious about complaints that the bass was too full with the foam removed from the vent since that was not my experience so far.
Now I understand what they meant. Without the fo.Q the bass was borderline bloaty and uncontrolled. Treble and mids were fine but not quite as clean to my ears. I don't mind a little loose booty so I still consider it an improvement over stock but a full step below having the damping added. Just wasn't as clean.
And this is where I want to focus on: the improved clarity, or perhaps resolution is a better word. I am not a headphone person. My real joy is speakers and DIY. From my experience one of the benefits of using very low distortion drivers is you're able to just keep turning up the volume without even noticing. That's what my 6XXs are like with the damping. That track by The Egg should be making my ears bleed as I turn up the volume, but it doesn't. And it's not attenuated. The mod increases the top end vs. stock no question. But it's so clean that it doesn't bother me.
Another example: typically I listen with the Asgard set to low gain. Personally I find it has a little better separation, sounds a little smoother than high gain with the 6XX regardless of DAC. Less punchy, sure, but smoother. But with the mod I can switch to the high gain and *crank* it and I get the punch and the smooth/ease. Couldn't do that before - no way. And it's not the DAC as I also have a diy Soekris that's easy like Sunday morning; didn't like high gain with that either.
All in all, the results have been fascinating. I look forward to hearing what the Second Skin has to offer when it arrives.
