Sennheiser HD 650 Mod Compilation
Jun 20, 2013 at 3:35 AM Post #16 of 66

PETEREK

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HD580 (Close enough) I covered the headband in a burgundy fabric, took the small foam padding out of the back of the drivers, and removed the padding inside the cups. I also cut the small plastic thing off that covers the driver on the inside of the cup to reduce the reflection of sound going back into the driver.

 
Apr 22, 2016 at 3:59 AM Post #18 of 66

UntilThen

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Besides the coin mod and removing the foam behind the driver, I apply Dynamat as shown. This mod enhance the bass, making it tighter and with greater impact. The 1st 2 mods opens up the high notes. HD650 now sounds lively, clear and impactful. Love the sound signature now.
 

 

 

 
Apr 22, 2016 at 11:12 AM Post #19 of 66

HemiSam

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I bought a Headamp GS-1 with the Dynalo+ boards and that enhanced the HD650...a lot.  Much livelier than out of the Woo WA7 which sounds great paired with my TH900's.  GS-1...best mod ever  
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HS
 
Apr 22, 2016 at 5:59 PM Post #20 of 66

audiojun

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@UntilThen
 
When removing the back foam, the spider behind the driver creates some nasty treble resonances that can't be EQ away the foam helped cushion and dampen those frequencies. Removing the spider solves this and IMO is the best mod I've done. It further increases the resolution and clarity and it makes the treble less fatiguing.
 
 
Here is how mines is modded so far.
 

 
Apr 22, 2016 at 6:41 PM Post #21 of 66

UntilThen

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@audiojun  how do you remove the spider? Do you have to break it? It seems to be tightly wedged to the driver.
 
Apr 22, 2016 at 6:51 PM Post #22 of 66

audiojun

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  @audiojun  how do you remove the spider? Do you have to break it? It seems to be tightly wedged to the driver.

Yeah it's broken off.
 
Just make 4 cuts on the ring in middle and then wiggle the pieces and it comes off easily. Don't let any of the pieces fall inside the hole.
 
 
made an illustration it's easy.
 

 
Apr 22, 2016 at 7:08 PM Post #23 of 66

UntilThen

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Thanks will try it now. Wish me luck. 
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Apr 22, 2016 at 7:17 PM Post #24 of 66

UntilThen

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Well that was easier than I thought. Just use a plier and break it gently and it comes off easily. 
 
Now to listen.... 
 

 
Apr 22, 2016 at 7:27 PM Post #25 of 66

UntilThen

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You're right. It did sound better or is that my imagination :)
 
I play a song that had high treble and which I thought had sibilance before breaking off the spider but now it's gone. 
 
Thanks for the tip. Now it's really irreversible but it's sounding so good why would I reverse it. 
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Apr 22, 2016 at 7:43 PM Post #27 of 66

UntilThen

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  Yeah the foam removal shouldn't be done unless the spider was removed as well imo.

Thanks champ. It is sounding very good now and the modded HD650 will be competing for my head time with my other T1 and HE560. With my tube amp Elise, it's amazing.
 
Aug 2, 2016 at 10:50 PM Post #29 of 66

DecentLevi

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So below is the end result of around 6 hours and at least a half dozen mod experiments on my HD 650:
 

   (photo is without grill, but am still using it)
 
Things tried with bad result:
  1. Dynamat+butyl on the backside of the grill facing the drivers with a checkered design (4 strips) 
      Seemed to have only shrank the soundstage
  2. Covering half, then covering all of the air holes along the back with butyl
      Increased the mid-bass hump and overall muddyness
  3. Trying the exact configuration as @UntilThen used above. On my pair this wasn't enough butyl+dynamat to make any noticeable difference
  4. Adding small rectangular-ish squares of butyl+dynamat around the 'spider' cone prior to removing it
      No noticeable result
  5. Adding cotton underneath the earpads to further extrude them by around 1/2 deeper than before
      Rather than increasing the soundstage, everything sounded more "back row". However the mid-bass hump was completely fixed
      
 
Things tried with good result:
  1. Inserting dynamat+butyl as shown above. I also made the longest strip a bit wider for a possibly better effect
      The above config. seems excellent for adding about as much more dynamics as possible without reducing the soundstage. Probably refines clarity a nuance by reducing reflections (see below)
  2. Removing the 'spider' and foam from the back
       Added a bit more clarity
 
During the process I realised how strange this is to put dynamat in this direction; that is facing away from the driver, and being in a location that covers nothing besides solid plastic surface. Because generally the purpose of dynamat is to absorb reflections of high frequences which is almost always done facing the driver. As such, I wasn't surprised that initially I couldn't really hear much difference when it was just the top, middle & bottom strips as UT had used above. When I really started noticing a difference was after I added more, per the photo. Finally this was starting to add a but more punch to the drums. As far as I can tell, the only benefit of using dynamat at all on this mod other than possibly looking shiny, is that just maybe it absorbs a nuance of the high frequencies from bouncing around inside the earcup more than once - that is, some of the high frequencies that echo back towards the driver from the grill may be cancelled out from further ricocheting. Otherwise, the bulk of the reason for this mod making any difference is only because of the butyl, so I wouldn't be surprised if someone could get more/less the exact result with butyl only.
 
I would have tried the coin-hole mod but was a bit hesitant since I'm sensitive to certain high frequencies. Maybe if I could find a cheap replacement earpad I would give it a go, as a backup in case I didn't like the result.
 
Overall I'm happy with the result and it is definitely somewhat more clear and punchy than before, but I wouldn't go as far as saying mine sounds akin to an HD '850' - maybe more like HD '690' in terms of difference from before. I recall a heavily burned-in HD-600 that I recently tried on this same system was clearer and punchier, with what seemed an even larger soundstage. I've currently got around 2,000 hours on my 650's at medium volume levels. Maybe I need to burn mine in at louder volumes in order to reach that next plateau of performance. 
 
Aug 2, 2016 at 11:28 PM Post #30 of 66

DecentLevi

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Also it's worth noting that the way I was able to accurately compare such small changes was by keeping one side un-modded for comparison until I was satisfied with the result; meanwhile playing a continuous loop of the same track - in mono to ensure consistent output to both sides
 

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