[kalbee]

I did read on some other site someone claiming Fiberloft or something of such similar name (the 'loft part should be correct) has better acoustic properties and also make softer pillows... Take it with a grain of salt though. May or may not be true.
 
As for fiberglass, should they also be put in very small quantities as teased cotton balls?

 

[bluemonkeyflyer]

Quote:

The T20RP white driver dampener looks different compared to the paper on the T50RP. It appears more dense and of a different composition. It does not look as porous as the T50RP paper.
The cup vents are covered with a single layer of very porous mesh instead of felt.
There is no plate covering the central screw compartment.
The driver appears to be the same as the T50RP. It has a single baffle port like the T50RP.
Mods that work for me on the T50RP do not work on the T20RP. This one will require a different approach.

 
T50RP is porous with fibers clearly present, running throughout.
 
 
 

 
T20RP dampener looks thicker and less porous without fibers running throughout.
 
 

 
Blue light behind open cup of T20RP shows that the mesh covering the cup vent serves only as a dust barrier, not as a dampener.
 
Note the stamp on the diaphragm - "Foster dp29 sz1d"  This is the sames stamp on all my T50RP's purchased in June, September, and December 2011.
 
 

 

[Nevod]

erroneous post

 

[Nevod]

BMF,
Looks like all the drivers, even older white ones have same writings on the diaphragm..
 
Indeed, T50s damper looks like T20s damper split in half parallel to the surface.
 
You said that T20RP requires a different approach to modding. I guess that the main difference is the damper, and the cups can easily be brought to some common denominator? And if one replaces the damper, then there is no serious difference?
 
 
A few days ago a thought occured to me. Why does the Sennheiser HD800 has a huge scene, as said by many people? There must be something to it. What makes it different? Ring driver. How it is different with regards to scene?
A common driver has large radiating surface and large run differences between ear-center point of driver and ear-side of driver. Same for any other point of pinna.
An bass-lensed driver has reduced radiation from sides and so is closer to a point source. However, it is a point source near the ear, and has high run length differences between it and different points of pinna, so the full sound waveform at ear canal entrance is still not correct.
An ring driver has its radiating surface right against the pinna, so there is less run length difference between inner and outer parts of pinna, hence it appears as a more remote source, hence the more correct full waveform at ear canal.
This is just a speculation, but seems plausible to me.
 
So I have tried to 'emulate' a ring driver using an reverse reflex dot of self-adhesive felt on ear side of the driver. My rig is pathetic, so I can't really say if there was any noticeable difference, but seems that scene has indeed improved somewhat. At least on pair vocal records, I can now hear that one is closer, one is a bit away, one is to the left, other is to the right. Before, they were in different places, but it was hard to say where.
Treble has increased a bit. Seems that 11kHz peak has been tamed by that dot. Can't still understand what's changed with treble over 16kHz.
Bass has reduced, though. And my pair is somewhat bass-shy now, EQing up by~3db/octave below 300 Hz produces a much more lush, PRaTty and involving sound. I'm thinking about combining the reverse dot with a bass lens for more bass, but that's not today.
Overall.. Hard to make a conclusion, it's a bit too subtle a difference.

 

[TierAngst]

I don't see that our local hardware store has it on their website but I've yet to go check it out personally. 
 
Is this the stuff you were talking about?
http://www.atsacoustics.com/item--Owens-Corning-703--1002.html

 

[glorydays]

I dont believe that fiberglass is working below 1khz. To fight the lower trouble range, I suggest making cavity resonators of plasticine along the walls where the sound is directed by diffusion. When I removed 170-300 hz by this, the 600hz became too prominent, so now  I have to try and tune some of  the resonators towards the higher frQ. Then stuff the cup's with fibreglass to cach the treble. Ever tried blowing in a harmonica? Top of a bottle? Pan flute? Even small cavity's made of small pipes make a sound, one end sealed and small opening on the other. Thats my 0,000002 for the moment. This might be a dead end, but I've declared war against every delayed backwave, so be It.

 

[RexAeterna]

I dont believe that fiberglass is working below 1khz.

that's not what my graph for my fostex say

http://i882.photobucket.com/albums/ac26/RexAeterna/T50RPRexFR.jpg


that play-doh stuff you guys use is not nearly as effective as fiberglass. fiberglass has been proven for decades to be insanely good absorber. you can find fiberglass data everywhere for speaker boxes and room acoustics. yea we're talking about headphones here and not speakers but the same fundamentals still apply. it just takes lot less in measurement since the enclosure and drivers are much smaller compared to speakers so it take much less for complete absorption. just saying.

diffusers is a great idea but probably gonna be very difficult to pull off properly for headphones due to the tiny enclosure. diffusion is harder to abstain then complete absorption(unless you go AKG route with passive diaphragms).

 

[RexAeterna]

I don't see that our local hardware store has it on their website but I've yet to go check it out personally. 

Is this the stuff you were talking about?
http://www.atsacoustics.com/item--Owens-Corning-703--1002.html

those are already made panels to buy. fiberglass should be in bags and should be pink with the pink panther on it(well mine are at my local home dept.) just ask the sells guy for home insulation and there should be tons of fiberglass and rock wool options available. there usually in big rolls but they do make very small bags of it for couple bucks. it shouldn't be very hard to spot.

 

[DaBomb77766]

Quote:

that's not what my graph for my fostex say
http://i882.photobucket.com/albums/ac26/RexAeterna/T50RPRexFR.jpg
that play-doh stuff you guys use is not nearly as effective as fiberglass. fiberglass has been proven for decades to be insanely good absorber. you can find fiberglass data everywhere for speaker boxes and room acoustics. yea we're talking about headphones here and not speakers but the same fundamentals still apply. it just takes lot less in measurement since the enclosure and drivers are much smaller compared to speakers so it take much less for complete absorption. just saying.
diffusers is a great idea but probably gonna be very difficult to pull off properly for headphones due to the tiny enclosure. diffusion is harder to abstain then complete absorption(unless you go AKG route with passive diaphragms).

The plasticine is used for a completely different purpose as the fiberglass...

 

[DjAmTraX]

This thread is a monster.  I am getting mine next week so I have high hopes. 

 

[TierAngst]

Quote:

owens rigid fiberglass can be bought locally at home dept or other home improvement stores

You said rigid so it threw me off, the stuff I linked to was rigid. And that was for sound purposes so I thought maybe you had to peal it off the board or something.

 

[proid]

Quote:

that's not what my graph for my fostex say
http://i882.photobucket.com/albums/ac26/RexAeterna/T50RPRexFR.jpg
that play-doh stuff you guys use is not nearly as effective as fiberglass. fiberglass has been proven for decades to be insanely good absorber. you can find fiberglass data everywhere for speaker boxes and room acoustics. yea we're talking about headphones here and not speakers but the same fundamentals still apply. it just takes lot less in measurement since the enclosure and drivers are much smaller compared to speakers so it take much less for complete absorption. just saying.
diffusers is a great idea but probably gonna be very difficult to pull off properly for headphones due to the tiny enclosure. diffusion is harder to abstain then complete absorption(unless you go AKG route with passive diaphragms).

I think fiberglass is very good to absorb mid and high frequency but it's not that good absorbing low frequency.

 

[RexAeterna]

I think fiberglass is very good to absorb mid and high frequency but it's not that good absorbing low frequency.

if fiberglass was only good for mid and high frequencies then they wouldn't be used for bass traps. it can be used for headphones as well but you have to figure out the proper measurements yourself and experiment. combine it with other material like polyfill/fiberfill and you have the whole spectrum covered for complete absorption. that's just the back enclosure behind the driver though. people forget about the front a lot and never take in mind that could make a big difference how the sound waves are fired into the ear cause planers of course are bipolar/dipole and fire in both directions evenly. like the shure 840 pads that's used a lot. you simply can stuff things in there to experiment. i find using the 240 foam disc(the thick foam disc in the 240 studio model) to work great cause it will help bring both the treble and bass up. you can also use things like cut outs of speaker cloths,cotton pads,very thin layers of silk,coffee filters,ect in different types of combination in different layering and so forth. it will help slow down and prevent resonance around the ear and help deliver a clean, smooth response. there is so many different ways to achieve multiple things. the possibilities are endless.

 

[RexAeterna]

The plasticine is used for a completely different purpose as the fiberglass...

yes i know. it's for mass vibrations. i just personally feel acoustic absorption is more effective when it comes speaker and headphone enclosures if your looking to completely eliminate enclosure resonance.

 

[kalbee]

Fiberglass should be used with other non-porous/non-fibrous materials to get full absorption range. This would be how bass traps work.
In general, lower frequencies are dealt better with non-porous/fibrous materials. These, however, will REFLECT high frequencies. That's why they're used together with fiberglass.
 
You can literally cut slits in a piece of cardboard, put fiberglass in cups, put cardboard w/ slits over, and cover again with fiberglass.
That said, I don't know how cardboard acts in terms of absorptivity, but wood and gypsum can be VERY good in these aspect.
Now tell me you want to put drywall (gypsum) or glass in your T50RP... good luck with that! I don't have the tools for it, otherwise it should 'technically' be good (according to the specs sheets anyway). Add wooden studs under the gypsum and you get the same effect as a house's wall.
 
 
The above is based on frequencie of 125Hz and above. Not quite low enough I know, but the frequency graph tends to follow the same trend. That said, it doesn't have to. Really low frequencies are hard to remove pure STC style.
 
On the other hand, my uncle showed me a method of soft-modding headphones... I get the concept but don't understand how it works to change sound. The method used was the same as how he 'modded' his grado (Alessandro MS-1 actually). I am going to mess around with it a bit more before concluding anything.
 
**EDIT** forgot to mention. It also depends how much fiberglass you use, and how compact you put them.