= Hifiman “Fuzzor” Mod = (Driver backwave felt damping modification)

[Hansotek]

Hmm, I wonder if it would affect the soundstage at all then, even if just very slightly?

Doubtful. Replacing the grill with a more open mesh will enlarge the soundstage. Be careful not to use any materials that are too thick if you do the outer grill replacement however, because those materials can cause some very nasty backwave treble ringing if they are too thick.

 

[gauchotodd]

I just degrilled mine and haven't bothered regrilling because when they're not on my head they're hanging up safely on the wall

 

[gauchotodd]

I did the fuzzor mod on both my 400s and 500s last night, and am in complete disbelief of how much better and more natural they sound. I didn't even do a perfectly immaculate job on them either, and I'm in shock at the improvement. So a huge thank you for sharing this mod and letting us get the sound out of these that both our ears and the cans deserve

 

[nehcrow]

Is 2.5mm thin enough?
http://www.ebay.com.au/itm/4-x-Large-Black-Felt-Furniture-Floor-Skid-Protector-Pads-Self-Adhesive-/331335874984?pt=LH_DefaultDomain_15&hash=item4d252839a8

Looking to get that, hopefully it's suitable

 

[coletrain104]

  I did the fuzzor mod on both my 400s and 500s last night, and am in complete disbelief of how much better and more natural they sound. I didn't even do a perfectly immaculate job on them either, and I'm in shock at the improvement. So a huge thank you for sharing this mod and letting us get the sound out of these that both our ears and the cans deserve

Do you feel that this mod changed the frequency response at all? Just curious. Waiting to part with my HE-400s because of tizzy treble

 

[gauchotodd]

  Do you feel that this mod changed the frequency response at all? Just curious. Waiting to part with my HE-400s because of tizzy treble

It did noticeably help with mid- and upper-range distortion and improved clarity/detail. I highly recommend both mods, they're not at all difficult and totally reversible, and for the fuzzor mod the HE-400 is notably easier than with the HE-500 because of the smaller drivers. I can try to find a picture of another member's result if that would help; my work was by no means immaculate and didn't even entirely cover the portion theirs did, so I suspect even better results than mine may be had.

 

[ThurstonX]

  It did noticeably help with mid- and upper-range distortion and improved clarity/detail. I highly recommend both mods, they're not at all difficult and totally reversible, and for the fuzzor mod the HE-400 is notably easier than with the HE-500 because of the smaller drivers. I can try to find a picture of another member's result if that would help; my work was by no means immaculate and didn't even entirely cover the portion theirs did, so I suspect even better results than mine may be had.

 
Agreed, it's worth trying both mods for oneself, as they are not difficult and are reversible.  BUT...
 
...does the HE-400 really have smaller drivers?  Aren't they physically the same size?  I was thinking all HFM cans in the "HE" line had the same physical dimension, at least in terms of circumference.  For example, aren't the grills interchangeable between all models?  If that's true, I'm curious what you mean by "smaller."

 

[Hansotek]

 
It did noticeably help with mid- and upper-range distortion and improved clarity/detail. I highly recommend both mods, they're not at all difficult and totally reversible, and for the fuzzor mod the HE-400 is notably easier than with the HE-500 because of the smaller drivers. I can try to find a picture of another member's result if that would help; my work was by no means immaculate and didn't even entirely cover the portion theirs did, so I suspect even better results than mine may be had.

Agreed, it's worth trying both mods for oneself, as they are not difficult and are reversible.  BUT...

...does the HE-400 really have smaller drivers?  Aren't they physically the same size?  I was thinking all HFM cans in the "HE" line had the same physical dimension, at least in terms of circumference.  For example, aren't the grills interchangeable between all models?  If that's true, I'm curious what you mean by "smaller."

They are actually a good bit smaller. You can see here the planar honeycomb structure is contained within this smaller plastic square:

 

[Hansotek]

 
I did the fuzzor mod on both my 400s and 500s last night, and am in complete disbelief of how much better and more natural they sound. I didn't even do a perfectly immaculate job on them either, and I'm in shock at the improvement. So a huge thank you for sharing this mod and letting us get the sound out of these that both our ears and the cans deserve

Do you feel that this mod changed the frequency response at all? Just curious. Waiting to part with my HE-400s because of tizzy treble

I tried it on the HE400, it didn't really help. The midrange backwave distortion that occurs on the stock HE500 isn't as much of a problem on the HE400. My theory is that the plastic structural overlay breaks a lot of it up. Combined with the sucked-out mids, you don't really get the same problem.

The mid treble ringing on the HE400 is an issue, however. Methinks this issue can be mostly attributed to that same plastic overlay. Plastic tends to cause nasty resonances a little higher up the frequency spectrum, between 6k and 10k. Creatology foam is usually a pretty good damping material to get these frequencies under control. It worked like a charm in the Beyer T1.

I haven't tried it yet, but I bet if you coated the entire plastic support structure in Creatology foam, it would ease that treble spike back down to a more reasonable level.

 

[ThurstonX]

They are actually a good bit smaller. You can see here the planar honeycomb structure is contained within this smaller plastic square:

Funky.  Thanks for the pic and the clarification 

 

[gauchotodd]

Like I said, I noticed a very audible improvement in both the mids and treble, but not so much with the bass. It doesn't create the realistic, textured sound that the similarly-modded 500s do, but it does make for a more enjoyable and less fatiguing sound.

 

[coletrain104]

Interesting. Maybe I'll keep the 400 as a mod tester. So, if the felt is glued on, to undo the mod, you'd have to take off the felt and scrape off the glue? curious because I don't want to affect my ability to sell it

 

[ThurstonX]

  Interesting. Maybe I'll keep the 400 as a mod tester. So, if the felt is glued on, to undo the mod, you'd have to take off the felt and scrape off the glue? curious because I don't want to affect my ability to sell it

 
If you use self-adhesive felt, like Creatology you can get in the US at Michaels, it's a simple matter of cleaning off any residue after peeling off the felt.  A little isopropyl alcohol on a cotton swab works great.  I speak from experience.  I had to undo the mod before sending back my previous defective pair of HE-500s.  Removing dried glue might be a flaky affair which could be difficult to keep out of the drivers.

 

[Hansotek]

Like I said, I noticed a very audible improvement in both the mids and treble, but not so much with the bass. It doesn't create the realistic, textured sound that the similarly-modded 500s do, but it does make for a more enjoyable and less fatiguing sound.

Interesting. Could you post a pic of your HE400 mod? I'd like to see what you did differently and continue progressing with this mod.

Also, can you let me know what pads you're using?

 

[Hansotek]

Interesting. Maybe I'll keep the 400 as a mod tester. So, if the felt is glued on, to undo the mod, you'd have to take off the felt and scrape off the glue? curious because I don't want to affect my ability to sell it

Some helpful links for you:

Here's the adhesive felt I used for the HE500 fuzzor. It comes on and off easily with very little residue:
http://www.amazon.com/gp/product/B0018N5W2Y/

Here's the link to the adhesive foam that I mentioned (often used to tame the treble in the HD800 & Beyer T1):
http://www.amazon.com/gp/product/B002JTRNIW/

I haven't tested the foam yet, but with all that plastic in the he400 cup, I have a feeling it might work.