HD650 KISS mod

Does putting Dynamat on the backside of the magnet (leaving the magnet hole open) increase, or decrease the bass impact vs the stock spider cage with foam?

I'm basically looking for more bass impact for the 650 but without boosting the uppermids and treble.

 

removing the foam increases mid bass, I guess that means you might perceive a little more impact but generally its just more bass but not particularly clean and tight if you leave it open. I left a thin foam layer on top of the hole for that reason, rather than open.

 

I don't mind it being a bit looser if it gets more impact. I only care about the mids and highs not getting any harsher/more resonant..

Do the upper-mids and highs get harsher/more resonant when leaving the magnet completely open vs stock spider + foam, does it get smoother or does it stay the same?

 

Its been a while and the main thing is that I did the whole mod in one go (including Dynamat) so I wouldn't be able to tell you exactly what the foam mod does on its own. I do believe that this has been documented very well on the original mod thread, maybe you'd find more information about this there.

Edit: I realised you also included the Dynamat mod in your question. In that case, I'd say that the upper mids don't get harsher, they are smooth but slightly more open. Definitely all in a good way, it takes away a bit of the darkness/dullness while keeping the general easy characteristic. I've got a bit of tinnitus going (from a bad ear infection last year) on so I'm a little sensitive to treble harshness and this will never trigger any annoyance for me

 

What works best to keep the bass boost as with the magnet hole open (or to get more preferably), but decrease the 5khz?

Asking because I’m listening to them right now with no foam and no spider cage, I like the slight bass increase, but I would like more if that’s possible with Dynamat for example, while lowering the 5khz bump.

 

Would covering the magnet with a donut of the stock back foam, while leaving the magnet vent in the middle open, decrease the 5khz bump, and keep the fast transient response and bass emphasis of having no foam there?

 

Would love to try this out. Anyone in CONUS got spare dynamat? Would rather not purchase a whole sheet to use a tiny fraction of it. Will pay for it + shipping.

 

Go to your local car audio shop and ask if they've got an extra square couple inches of dynamat extreme - I'll bet they do, and they'd be willing to just give it to you! you really only need about a 4x4 inch square.

 

See: https://www.secondskinaudio.com/sound-deadening/damplifier-pro-small-project.

 

So, I wanted to share something. Can't really tl;dr this, it's been a journey.


I'd done the KISS mod two or three years ago, loved how the thing woke up, cleaned up and sounded overall better. Fell in love with the HD650 since then!

Last Saturday I was in the mood for one of those all night listening sessions, but not before having checked what was up around here (love lurking from time to time). Couldn't help but reading the JAR600 measurements and seeing this work of art.

I went at it, and then on Sunday it occured to me. Why not try something along the lines of the JAR600's material shape on the driver and the magnet? I had some left over dynamat from the first KISS mod.... and I already have a fresh memory of all my favourite music! Let's do it!

After some time and careful prying, all the dynamat and creatology like foam I'd used came off. It's sticky, but thankfully since the drivers' plastic and the magnet surfaces are smooth, it doesn't get glued to them. What I'd noticed is that the foam disc (folded in half) had come apart in the places I'd added a little dynamat tar to keep them together. As a result the magnet hole was not completely covered nor flush with the foam, this explains why I'd noticed the bass so prominent lately with some loss of detail.

So, had a look at the work of art? Took that design, 'shopped it to get an outline, scaled it to match the HD650 driver size, printed two pairs out, and cut one set for each driver. Then, with the other pair, cut another set and added another layer on top. Why so much dynamat vs regular KISS mod? Well, the JAR600 has a lot of material in there... why not try this out? Can't hurt to give the driver more mass than the standard.

Finally, took some measurements to get a shape similar to the candy wrap that's on top of the driver in the JAR600, punched out a hole in the middle like the work of art, cut out a little foam disc from the piece folded in half (it was originally part of the front foam covering the driver dome), put it in place and added the candy wrap on top. I hesitated here, having read that one or two layers controls how much midbass you get... decided to do one layer. Thought I could just tape a second layer on top if I wanted later.

To top it off, I wanted to couple the driver more to the baffle as I'd read this (plus more driver mass) results in more bass extension. I'd already gotten dynamat on top of the four plastic clamps that hold it in place to enhance the grip, as you can see the dynamat extends a bit on to the drivers' sides. I just cut two strips of dynamat and added them to the drivers' arm where the cable plugs in, on their sides where they meet, effectively coupling that part of the driver assembly better to the baffle.

Spoiler: more pics

You'll notice a few things different from the KISS mod so far:

• Not KISS anymore, considerably more measuring and cutting. Front foam cutout is the same in both mods.
  
• Lots more dynamat on the driver (two layers overall plus a layer over the magnet and sides), headphones are noticeably heavier now
• No dynamat on the baffle. Just these two little strips further joining the driver arm/connector assembly to the baffle.
  
• Foam on the magnet hole is held in place by the dynamat candy wrap on top, just like the work of art linked above. It's not coming apart anymore, nor is there any other path for the air to go through but the foam. (like the original spider + double/triple layer foam arrangement)
• Didn't bother with the creatology like foam on top. Just painted the dynamat black with a sharpie. IIRC OP himself said it was just to make cutting easier somewhere in this thread.

Did both sides like this, plugged them in expecting to hear the sadness that are broken drivers, but thankfully everything turned out to be fine, lol

Well, got comfortable and started listening to the stuff I'd gone through that last night for changes. I sincerely wasn't expecting anything out of this, I'd done it mostly for the tinkering and entertainment value.

Something was immediately different. I could hear some more detail. Went through Radiohead's In Rainbows from the basement. At some point Thom coughs in front of the mic while the rest of the band is preparing for another song. I couldn't hear that detail last night... now I could. It was clear and it wasn't lost in the random instrument sounds in betweet. I couldn't help but notice how I could now feel the bass around the ears, not just hear it. f'ing thing was kicking me in the head! Definitely more bass extension now.

Imaging improved, got more focused. I could better pinpoint out individual instruments in the soundstage. This could be just from fixing the foam on the magnet... but then I'd never had it this tight on there save for the time the spider was holding the foam disks in place... I could get a better sense of the size of the room where Another Brick In the Wall pt.2's kids all chant their lines, and how many there were, it didn't sound like a single voice anymore...

At that point I got emotional. I'm a pretty poker faced guy, but damn I was tearing up. What the f**k? THE f**k? These headphones had never done this to me, and I've had them since 2015 (I'd recently gotten new pads and headband as the foam was done for. Driver printed date is October 2014). Pleasure and bliss, yes, but tearing up? Hell no! Did some more Pink Floyd, went on to some Metropolis Pt. 2, some live Nightwish concerts I'd been to... Had a tear or three come out at some point. Had to stop listening at some points too to better understand what the f**k was happening to me.

I also couldn't help but notice some recordings now sounded like shit. These weren't gentle and forgiving as the stock HD650 are known for. Shit recordings became apparent, but good recordings got even better.

I could crank the volume up higher before going "too loud", or "that's uncomfortable". Less bass distortion as a result of the higher mass vs the regular KISS mod?

f'ing hell. What have I done? What is this?



To illustrate, my DAC is a lowly Xonar DX soundcard (changed opamp from NE5532 to OPA1612, bypassed output caps, DC coupled, no DC offset so far, for years), and my amp is a DIY SMD version of The Wire (LME49990 + LME49710 opamp+buffer combo, DC coupled, single ended, unity gain, ±18v, heatsinked, with the PSU being ±24v CRC filtered with near 12k uF capacitance per rail feeding dual LM317/337s in a tracking preregulator configuration). So, nothing special, probably utter crap by commercial gear standards.

Got this improvement on that crappy chain...

If anyone wants to validate these findings, go ahead. I wasn't expecting any change. Actually I was expecting things to get worse from so much dynamat (overdampening) but it seems there still was some room to not f**k things up.

 

Edit: the bass distortion was due to my WA6-SE going wonky, not the mod! All is well.

Just tried the KISS mod last night, used some auto dampening material from 3M and I thought it went quite well. Unfortunately on some songs I am getting distortion in the bass (aka fartbass™). Can anyone help me figure out how to fix this? It's not too easy to hear from the video but I tried taking one anyway..,

 

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.

Pic:

 

Does anyone know if this mod will fix what I perceive as shouty female vocals on the 6xx?