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= Hifiman HE500 & HE400 Jergpad Mod v2.5 = - Page 83

post #1231 of 1702
Thread Starter 
Quote:
Originally Posted by kard16 View Post


The viscoelastic material should also absorb the backwaves. Weather it's worth the cost, if it's easy to work with, or has any other unintended consequences is another matter

I don't think the smooth surface layer of the dynamat is good for direct absorption, there's a reason why direct acoustic damping material tend always to be extremely porous. Maybe if you can find dynamat without the metallic surface layer it'd work. Vibration damping is a whole different thing here.

 

If you don't believe me, look into popular damping mods (e.g. T50RP mods, Denon D2/5/7k mods), dynamat is always applied to the back and around the drivers, while porous damping material (whether it be foam, felt, or something similar) is applied on the inner faces of the drivers. They serve different functions.


Edited by jerg - 11/19/13 at 10:24am
post #1232 of 1702
Quote:
Originally Posted by jerg View Post

I don't think the smooth surface layer of the dynamat is good for direct absorption, there's a reason why direct acoustic damping material tend always to be extremely porous. Maybe if you can find dynamat without the metallic surface layer it'd work. Vibration damping is a whole different thing here.

If you don't believe me, look into popular damping mods (e.g. T50RP mods, Denon D2/5/7k mods), dynamat is always applied to the back and around the drivers, while porous damping material (whether it be foam, felt, or something similar) is applied on the inner faces of the drivers. They serve different functions.

Yeah I see what you mean. I'll probably try felt on the inner face of the driver, and maybe a viscoelastic material on the back (at the very least around the inner ring of the earpiece).
post #1233 of 1702
Quote:
Originally Posted by kard16 View Post


The viscoelastic material should also absorb the backwaves. Weather it's worth the cost, if it's easy to work with, or has any other unintended consequences is another matter

 

Been reading about FatMat.  If you want your cans to smell like asphalt...  ;-)  Apparently that smell dissipates over time.  I wonder about the thickness, esp. vs. the stiff felt, which seems about right.

 

If you do it, take pix!

post #1234 of 1702

Here are some photos of the felt mod.

 

I used the thin sticky felt to cover the middle bar.  I cut a 7-8mm wide strip, centered it, used thumb and forefinger nails to pinch it, then a tongue depressor type stick (flatter on the end and a little wider) on one side to get it as snug as possible, using other thumb to secure/pinch the other side.  When using just the stick, the opposite side tended to come unstuck a little.  Then I did the same on the other side.  I left it alone for an hour or so to see if it would stay adhered, and it did.

 

You get a hint of my grill mod in the first photo.

 

 

 

 

 


Edited by ThurstonX - 11/19/13 at 1:34pm
post #1235 of 1702
Quote:
Originally Posted by ThurstonX View Post

Been reading about FatMat.  If you want your cans to smell like asphalt...  ;-)  Apparently that smell dissipates over time.  I wonder about the thickness, esp. vs. the stiff felt, which seems about right.

If you do it, take pix!

I think I'll try the fatmat on the back side of the drivers and around the inner ring of the housing (the area underneath the grill). I'll use felt on the inner driver face. Might even do that tonight if I have time.
post #1236 of 1702
Quote:
Originally Posted by ThurstonX View Post

Here are some photos of the felt mod.

I used the thin sticky felt to cover the middle bar.  I cut a 7-8mm wide strip, centered it, used thumb and forefinger nails to pinch it, then a tongue depressor type stick (flatter on the end and a little wider) on one side to get it as snug as possible, using other thumb to secure/pinch the other side.  When using just the stick, the opposite side tended to come unstuck a little.  Then I did the same on the other side.  I left it alone for an hour or so to see if it would stay adhered, and it did.












Looks really slick.
post #1237 of 1702

Here's my attempt:

 

I kept the strips pretty thin (~3mm).  I also didn't do those little triangle wedges.  Too much effort.  

post #1238 of 1702
Quote:
Originally Posted by kard16 View Post
 

Here's my attempt:

 

I kept the strips pretty thin (~3mm).  I also didn't do those little triangle wedges.  Too much effort.  

 

Very nice, esp. the center bar  ;)

post #1239 of 1702

^ and what are you guys trying to gain by doing this?  I might have missed that post and too lazy to read back.  :)

post #1240 of 1702
One thing I noticed is that open slits leading to the diaphragm are not straight, but jagged, if you will. Yet, you guys seem to be applying the felt as straight pieces. I think having to cut the felt to exactly match the open pattern on the metal would be a real PITA. Are you guys just ignoring that and going over a bit to cover the jaggedness or what?
post #1241 of 1702

This mod could be accomplished by putting a disk of felt inside the pad as well, though you will be slightly dampening the waves as they reach your ear as well as the reflected wave. In my experience, felt in front of the driver on my T50RP's makes for a veeeeery subtle decrease in treble. Seems to me that if you are having a bit of treble issues anyway, you could use the felt disk inside the pad and avoid having to stick anything to the driver magnets. (Are those the driver magnets, or just a metal cover?)

post #1242 of 1702
Thread Starter 
Quote:
Originally Posted by hans030390 View Post
 

Well no, they are more or less straight slits, the metal grid has jagged edges but the magnets that are directly bonded to them are all rectangular.

post #1243 of 1702
Quote:
Originally Posted by jerg View Post
 

Well no, they are more or less straight slits, the metal grid has jagged edges but the magnets that are directly bonded to them are all rectangular.

 

Ah, thanks! I obviously failed when I examined it... :redface:

post #1244 of 1702
Quote:
Originally Posted by koiloco View Post
 

^ and what are you guys trying to gain by doing this?  I might have missed that post and too lazy to read back.  :)

 

Harmonic Convergence of the Spheres  ;)

 

I think you'll need to read back, but it has to do with back waves (or is it "backwaves"?  are cans singular or plural?  I suppose I should go with plural, eh?  You've got a left and a right headphone.  I have trouble writing correctly in these threads!).  These cause a resonance(?) with the driver frame that leads to some fuzziness.  The felt absorbs the backwaves, thus clearing up the sound a bit.

 

But don't shoot the messenger, even if I did get something wrong.  It's a fuzzy memory that has yet to get juiced (coffee).  Read back or wait for jerg to give a proper explanation.

 

Inexpensive, a little tedious, but not difficult to implement.  Do it on the outer frame, too, for that "cool guy" effect, esp. if you did the re-grilling mod.

post #1245 of 1702
Quote:
Originally Posted by koiloco View Post

^ and what are you guys trying to gain by doing this?  I might have missed that post and too lazy to read back.  smily_headphones1.gif

I think a short hand explanation would be that a lot of the higher frequency waves reflect back and forth between your head and the driver frame causing a bit of reverberation (the reason it's mostly higher frequencies is because sound is reflected provided that the reflective surface is large relative to the sound wave, and since lower frequencies have a wavelength much larger than high frequency waves, they wouldn't get reflected as much). The felt should absorb some of those reflected waves which should cut back on the reverb and add clarity.
Edited by kard16 - 11/20/13 at 1:15pm
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