[tashlin]

I love my HD650s for listening to bright recordings when my more aggressive headphones sound too harsh/ssssibilant and become fatiguing very quickly.  However, the 650s were actually just a little too smooth for my tastes (no doubt the "infamous veil"!) and so I started to consider a couple of mods.
 
I have now removed the foam inside the earcups and I find this to be an improvement.  Everything just sounds a little less muffled/diffuse, particularly at the top end, but the music still has a nice smoothness to it and doesn't cross over into sounding harsh.
 
Job done you might say!  However....
 
I see on the Apuresound web site that they suggest going a stage further - removing the grills to pull out the small piece of foam from behind the driver as well.
http://apuresound.com/hdsennmod.html
 
Please can someone tell me what this is likely to do to the sound signature?  I have seen a few comments on the combined effect of both mods, but am specifically interested in the incremental effect of removing the foam behind the drivers.
 
I'm interested in doing this because I still find the bass to be a little too loose/diffuse/muffled so tightening this up slightly would be welcome.  However, I am now happy with the treble/brightness following the first mod so I don't want to risk making them more aggressive/forward at the top end (which would defeat the whole point of me using the HD650s in the context of my first sentence above)
 
This extra mod looks quite hard to reverse (?) so I'd really appreciate some comments before I decide whether or not to risk it!

 

[tashlin]

Come on .... someone must know?!
 
The quick summary of my question = How does removing the foam from behind the drivers affect the sound signature of HD650s?  Also, if I try doing this and then don't like it, can I easily reverse it?
 
Thanks

 

[Categg]

This sounds interesting, i have been been using the HD650's (old version) without the foam for some time and i quite like it. I wonder what changes does removing the foam behind the driver will lead to too..

 

[winma]

Well, you can hear some difference, i made that mod with a friend who owns an old version of the 650's. 
 
Check this. 

 

[tashlin]

Thanks Winma ...although I think most of the posts in the link seem to be talking about removing the large foam pad inside the earcups?  I've already done this but I am now wondering about taking out the much smaller circle of foam wedged in between the plastic housing/structure and the back of the drivers (i.e. beneath the removable grills rather than inside the ear cup)?

 

[Categg]

I just tried to remove the foam behind the driver, it seems like it's glued stuck there and i don't feel like destroying the foam. Guess i'll skip this mod... it's too bad the link from apuresound doesnt describe what are the main changes from doing this mod..

 

[Cpyder]

I just tried to remove the foam behind the driver, it seems like it's glued stuck there and i don't feel like destroying the foam. Guess i'll skip this mod... it's too bad the link from apuresound doesnt describe what are the main changes from doing this mod..

I recently performed this mod and I know what you mean about the foam seeming like they are glued in there. There aren't; I believe it is just pinched between the plastic during construction. I tore the first foam I took out on accident because I wasn't patient but the second one came out easily once I knew what I was doing.

Take your tweezers and reach in through the middle circle towards the edge of the foam pad and grab as much of the foam as you can and pull towards the middle. Go around in a circle and you can easily pull the foam out without tearing them.

I don't know what effects just removing the rear foam does as I removed both the fronts and rear at the same time. To me the effect on the sound was drastic. The notorious veil was drastically reduced. High frequency sounds are clearer. I highly recommend it. The only drawback is that it's noticeably brighter. Not too bright, but if you listen at loud volumes, you might get listener fatigue quicker.

 

[Categg]

Thanks Cpyder for the tips. I finally managed to remove the foam behind the drivers! A brief listen seems to indicate that there's more details in the highs (especially sensitive on crackles and hiss on recordings).. as i already have a zu mobius cable which already brightens up the sound i think that it's too much of a good thing. Thankfully the mod is somewhat reversible..

 

[Cpyder]

Thanks Cpyder for the tips. I finally managed to remove the foam behind the drivers! A brief listen seems to indicate that there's more details in the highs (especially sensitive on crackles and hiss on recordings).. as i already have a zu mobius cable which already brightens up the sound i think that it's too much of a good thing. Thankfully the mod is somewhat reversible..

Your welcome. What differences does the upgraded cable make? After hearing a drastic change from simply removing the foam, I'm now interested in other upgrades like cables. I've always been weary with cable upgrades due to an almost complete lack of scientific backing. So tell me, is it worth it?

 

[Categg]

Well I'm familiar only with my zu mobius cable so i can't speak for the other cable types but to me i think that the Zu cable brightens up the recordings overall and increases instrument separation and detail while tightening the bass somewhat (less bass body, more definition). Downside is that vocals could start to sound a bit grainy and it'll definitely sound over-bright for long listening sessions.. to deal with that i've stretched a thin layer of pantyhose over the drivers and it seems to be somewhat of my ideal listening setup so far.
 
The difference is definitely there but how big the changes are is really up to each individual i think.. for me i think it's not a terribly high in value purchase but if you're willing to go for the last 10% difference then by all means go ahead. I think a better amp or source still provides the most difference for the HD650!

 

[9pintube]

You are so right with that statement Categg, I've found with most Senn. HD-650's and even the newer HD-800's the amp you are using makes a huge difference.......As far as cables go,I use the Double Helix cable on my HD-650's and I found the after market cable tightens "Things" up, especially the bass and seems to lift that VEIL many people hear and complain about with the HD-650's.......You say a 10% difference, I'd have to agree, but that's the last 10% I needed to really start enjoying my 650's.........But, I must re-state just how important your amp is when it comes to ringing the best sound out of the Senn. Headphones....JMO...

 

[Cpyder]

Thanks for the advice guys!

 

[Uchiya]

Did it, loving it!

 

[LugBug1]

Hi, just done the foam mod. First I removed the small piece from the drivers and had a listen. Much better! bigger bass impact and that nasty veil lifted. I then removed the foam from the insides (make sure you remove the pad cups first rather than tearing them out and then you can put them back if you wish). Again, even more clarity and dynamics. However there is now just the slightest of hardness and the sound is verging on being clinical from the mids up. 
 
So.. I didnt want to put the foam back and wanted to try something thinner. After rummaging through my wife's draws I was unable to find some tights.. So I just used my own(joking!)
 
Instead of using tights I used some material from a very thin scarf, almost the same consistency as bandage cloth. This has worked brilliantly, it has ever so slightly smoothed the top end without losing any of the new modded sound.
 
Try experimenting with different cloths in the ear pads, denser material will smooth out the sound more, but also may dull-en it too, so its a very fine line. 
 
Its like having new set of cans!

     

 

[LugBug1]

I've discovered the perfect replacement of the foam (on driver).
 
Toilet paper....
 
Yes. Toilet paper. If you part the two sheets so you only have a very small part of very fine paper and use sparingly! its works very well for me. I've put the foam back onto the ear-pads themselves as I think this keeps the frequencies separated better.
 
The sound is now (on pre 2007/08 model) attacking and sharper from the mids up and the bass is big, but not too big and is also more controlled in regards to having nothing on the drivers at all.
 
Re-cabled, modded, new pads. Sorted. Still 650 sound, only better (for me anyway).