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

post #1 of 58
Thread Starter 

Hifiman “Fuzzor” Mod

v1.0

 

 

                      

 

 

 

 

 

 

 

 

Prelude

 

 

 

This modification, which applies directly to HE500, HE5LE, HE4, and HE6 drivers (but derivative mods can be done on other HFMs as well as planar magnetic drivers in general), evolved from a number of things I tried.

 

Audeze’s recent LCD-X and XC had a new driver technology called “Fazor” which is a waveguide array that sits on top of the drivers and help direct the soundwaves more uniformly out of the diaphragms through the slits. I really wanted to do something similar with my HE-500s but couldn’t find any suitable material. Its design always sat at the back of my head though.

 

Meanwhile, I was fooling around with tuning the upper end balance of my HE-500s with felt discs; it never worked out right as it would introduce peaks and dips despite broadband attenuation of the frequency response. But one phenomenon I observed was that the felt discs always made the clarity better, the transients faster, which dumbfounded me as they were blocking everything and toning down the treble and thus should blur the clarity rather than enhance it.

 

I saw a modification done by purrin on his Abyss headphones, where he used damping material on the baffles of the driver cups to tame the treble peak, the mechanism described was that it helped diffuse away backwaves that bounced between the face and the baffle interface introducing unwanted reverberations.

 

And then it occurred to me that I could do a very precise damping scheme to completely cover the reflective surfaces of the HE-500 drivers without hindering any of the magnetic array slit openings. After some fooling around and a few revisions it came to fruition.

 

I did encounter a caveat initially with doing this modification, where the stiffened felt is somehow rigid enough, that it acts as a waveguide too well especially for the treble region, and the end sound was stringent around 10kHz. The simple solution to this, I found, was to taper off the right angles of the felt strips; that extra step has been included in the below guide to the mod.

 

 

 

 

Tools & Materials

 

1x sheet of Adhesive-backed Stiff Felt

            (Creatology-brand 9’’x12’’ sheets are only $2/sheet from Michael’s Arts/crafts store; online you can find 9''x12'' adhesive-backed felt for around $3-5/sheet plus shipping)

 

1x metric ruler

 

1x fine-tipped pen

 

1x sharp scissors / xacto knife

 

1x relatively thick pen or rod (~2cm diametre)

 

 

 

 

 

 

Protocol

 

As the main goal of this mod is to more adequately damp the soundwaves perpendicular to the drivers, between the drivers and the face, the felt is to be applied to the inner (face-facing) sides of the drivers, which can be exposed simply by taking off the earpads.

 

Below is a schematic of the cutouts you need to do out of the adhesive-backed felt sheets in order to apply proper damping to the HE500 (as well as HE4, HE5LE and HE6 drivers which have the same magnet grid patterns).

 

My method involves outlining all these cutouts on the waxy backing paper of the felt, with a fine-tipped pen; then going around cutting these out precisely using scissors or xacto knives.

 

 

Note that the cutouts are colourcoded in my diagram, this way I can show where they go and how they go onto the drivers in the below photo that has been colourcoded to correspond to the pieces from the cutout diagram, as seen below (click it to magnify and see the details and colour-coding clearly).

 

(note that the outer ring of felt as seen above, is actually part of the HE500 driver, it's a half-arsed but commendable attempt from Hifiman to damp the baffles of the drivers).

 

When applying the adhesive-backed felt stripes and pieces to the drivers, make sure to line things up well enough that you never block the driver opening slits; this requires patience and more patience, as they lay down those felt strips onto the metal surfaces of the drivers.

 

This is a more direct mod than any of my other mods (regrilling mod / jergpads mod) so it makes sense that you aspiring modders out there want to be more stringent through this process, get all the measurements and cutting and adhering neat and down to the tee.

 

One last step after successfully applying the felt is to round off / taper off the right-angled edges of the felt cuts, so that they don't interfere with the treble (as mentioned in the Prelude section of this guide). It's quite easy, just find a thick pen, and use its rear end to reshape and smooth out the edges of the felt. A stylized diagram is shown below:

 

 

 

It took me about 40 or so passes of the pen to smooth out each edge of the stiff felt, you can do more or less as you feel fit.

 

Optionally, you can also do the same procedure to the outside-facing faces of the drivers (that are under the Hifiman grills), that is far less important but you can do it for aesthetic reasons, and of course, you can never have too much non-intrusive damping!

 

And with that, you can completed the Fuzzor mod!

 

 

 

 

 

 

Impressions

 

(under construction)


Edited by jerg - 11/29/13 at 2:45pm
post #2 of 58

subbed. Thanks for the hard work Jerg!

post #3 of 58

Thanks for sharing this, jerg!

 

Rounding off the felt (as shown in the cross section view) was something I also had in mind... Important unless you get really thin felt or velour.

post #4 of 58

My current config on my HE-6:

- rear: regrilled (more open backed), removed cotton

- front: acoustic foam strips on the magnet plate only, not on the surrounding area

- additional felt disk on top

- J$ leather Beyer pads, on the stock mounting ring

 

 

Very minor change when I added the foam strips, but it seems to notch down a tiny ridge in the treble and improves the sense of space.


Edited by Armaegis - 11/29/13 at 5:43pm
post #5 of 58
Thread Starter 
Quote:
Originally Posted by Armaegis View Post
 

My current config on my HE-6:

- rear: regrilled (more open backed), removed cotton

- front: acoustic foam strips on the magnet plate only, not on the surrounding area

- additional felt disk on top

- J$ leather Beyer pads

 

 

Very minor change when I added the foam strips, but it seems to notch down a tiny ridge in the treble and improves the sense of space.

Your felt disc is already doing the job (and more), so the acoustic foam strips are not that useful in that modding configuration I think. That's why you aren't detecting any considerable change because the intended function has already been covered by the felt disc.

 

The strength of the Fuzzor mod is the ability to leave the diaphragms completely uninhibited and open still, while adding better damping to the driver space.


Edited by jerg - 11/29/13 at 5:33pm
post #6 of 58

There was still some space in front of the magnets though, as I use the stock mounting ring to hold my pads in place (I think yours is just taped down?). The felt wound up bowing inwards a little bit. The foam strips does even it out a bit, and I think does mitigate the very very minor reflections around the edges. I suspect it does "guide" a little better as well, which accounts for a slightly increased "presence" that I can feel, though it doesn't seem to be a change in frequency response.

 

I never thought that the felt disc produced the peaks like you mentioned. But the felt I use is probably different from yours.

post #7 of 58
Thread Starter 
Quote:
Originally Posted by Armaegis View Post
 

There was still some space in front of the magnets though, as I use the stock mounting ring to hold my pads in place (I think yours is just taped down?). The felt wound up bowing inwards a little bit. The foam strips does even it out a bit, and I think does mitigate the very very minor reflections around the edges. I suspect it does "guide" a little better as well, which accounts for a slightly increased "presence" that I can feel, though it doesn't seem to be a change in frequency response.

 

I never thought that the felt disc produced the peaks like you mentioned. But the felt I use is probably different from yours.

No the felt disc does not create peaks like I mentioned, it's the cut 90-degree edges of the felt (or in your case foam) strips that seem to be doing it.

post #8 of 58

Given that this is supposed to remove backwaves off the ear/face, I assume that this concept generalizes to all headphones and not just planars?

post #9 of 58
Thread Starter 
Quote:
Originally Posted by SanjiWatsuki View Post
 

Given that this is supposed to remove backwaves off the ear/face, I assume that this concept generalizes to all headphones and not just planars?

Yes, and in fact other analogous forms of it (for the same purpose) are used in other mods or stock headphones I think, though the cases are very few. Maybe a couple of T50RP mods have it.

 

I also know (after I've already devised this mod of course) that at least one person has done a similar form of this mod on Audezes, privately.

 

Planars with regular rectangular slits are definitely the easiest to mod this way. In this thread I'm just outlining explicit details toward exactly how to do it with higher end Hifiman cans, all the nuts and bolts and measurements and specs, tricks and hints.


Edited by jerg - 11/29/13 at 6:07pm
post #10 of 58

Always interested in such mods. Good luck Jerg.

post #11 of 58
Thread Starter 
Quote:
Originally Posted by nk77 View Post
 

Always interested in such mods. Good luck Jerg.

Thanks but why would I need luck? I already applied the mod (someone's gotta take photos) lol.

 

If you mean good luck to the popularity of this mod, well I don't mind if only a couple of people try it, it'll be the little secret.


Edited by jerg - 11/29/13 at 9:38pm
post #12 of 58
Quote:
Originally Posted by jerg View Post
 

Thanks but why would I need luck? I already applied the mod (someone's gotta take photos) lol.

 

If you mean good luck to the popularity of this mod, well I don't mind if only a couple of people try it, it'll be the little secret.

Oh no no. By luck I meant your attempt to use this as a startup to take over the world. Good Luck! On a serious note, I thought this was an unfinished mod without reading the whole post.

post #13 of 58
Quote:
Originally Posted by jerg View Post
 

Yes, and in fact other analogous forms of it (for the same purpose) are used in other mods or stock headphones I think, though the cases are very few. Maybe a couple of T50RP mods have it.

 

 

A lot of T50rp mods have felt on the baffle-ear-side, though more surrounding the driver rather than criss-crossing across it.

post #14 of 58
This evening I mounted felt on the magnet grill (on the ear side only). Kept HE-6 stock otherwise, with pleather pads.

This felt mod does tame the upper frequencies as I wanted. For some reason I also feel the general tonality has been tilted a bit - or at least I think I hear more bass ... which doesn't really make sense if it isn't a general tilt of the frequency response.

I think depth and holographic imaging is better defined, but sounds seem to bee closer. The sound is more rounded, "analog"?, and voices sounds more natural.

To me HE-6 now has a close to optimal frequency response. Don't need other headphones ;-)
post #15 of 58
Quote:
Originally Posted by LarsHP View Post

This evening I mounted felt on the magnet grill (on the ear side only). Kept HE-6 stock otherwise, with pleather pads.

This felt mod does tame the upper frequencies as I wanted. For some reason I also feel the general tonality has been tilted a bit - or at least I think I hear more bass ... which doesn't really make sense if it isn't a general tilt of the frequency response.

I think depth and holographic imaging is better defined, but sounds seem to bee closer. The sound is more rounded, "analog"?, and voices sounds more natural.

To me HE-6 now has a close to optimal frequency response. Don't need other headphones ;-)

Just speculating here, but could it be that the reduced high frequency response allowed you to turn up the volume, making for a perceived increase in bass response?  Not sure.  

 

Thanks for your comments. They are pushing me toward the edge to do this mod on my HE-6... 

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