[bapspidoff]

Thanks everyone for your tips and advice. After fooling around for a couple hours I think I have found the sound I was searching for. This is what I did:
 
1. Added a ring of silverstone foam to the ear side baffle with a 4x4cm square cut out in the middle over the driver.
2. Inserted a 4x4cm square of stiff black felt into the square hole in the silverstone foam.
3. Added more teased cotton balls into the cups (1 cotton ball each)
 
From what I can tell, the silverstone in the ear side baffle helped remove some of the resonance from the upper mids / lower treble. The stiff felt over the front of the driver tamed the treble and some of the upper mids and likely cut down on the resonance as well. After those two mods I noticed that the treble detail wasn't where I wanted it to be so I added more cotton into the cups which brought back just enough detail for my liking.
 
Now I am a happy man! 

 

[TK277]

I thought they were pretty good for $74. And the modding options made 'em better. The Shure pads by themselves with no extra modding made the sound more veiled than it was previously too... so stock, for $74 seems fair. I don't know what closed headphones would be better at this price point.
 
I then modded them and quite enjoy them.
 
I followed BMF's v8 to the letter, but the bass was non-existent, so I removed the felt over the vents and now I quite enjoy these. I even prefer them over my Grado and Sennheisier models. The bass doesn't bleed into the other frequencies at all and if there was a way to keep it that way I'd actually prefer the bass to hit even harder...it's about on par with the Senn 598s now, and those are an open can. Cups are filled with the Rite Aid fluff. Mad props to BMF!
 

 

[wje]

Quote:

I thought they were pretty good for $74. And the modding options made 'em better. The Shure pads by themselves with no extra modding made the sound more veiled than it was previously too... so stock, for $74 seems fair. I don't know what closed headphones would be better at this price point.
 
I then modded them and quite enjoy them.
 
I followed BMF's v8 to the letter, but the bass was non-existent, so I removed the felt over the vents and now I quite enjoy these. I even prefer them over my Grado and Sennheisier models. The bass doesn't bleed into the other frequencies at all and if there was a way to keep it that way I'd actually prefer the bass to hit even harder...it's about on par with the Senn 598s now, and those are an open can. Cups are filled with the Rite Aid fluff. Mad props to BMF!
 

 
So, in your experience, keeping all of the vents on the lower level of the cup meant for less bass?  Most people have really benefited by closing off those vents.  Some people have kept one vent open, or used a small piece of tape over that last, single vent to have some control in fine-tuning the bass a bit.  I've only worked with the closed vent versions and that's where I've been the happiest with the bass performance.

 

[TK277]

Quote:

 
So, in your experience, keeping all of the vents on the lower level of the cup meant for less bass?  Most people have really benefited by closing off those vents.  Some people have kept one vent open, or used a small piece of tape over that last, single vent to have some control in fine-tuning the bass a bit.  I've only worked with the closed vent versions and that's where I've been the happiest with the bass performance.

Correct. When I had the vents closed with the original felt and electric tape over that, they were very bright. I'll post pics of what I did the headphones soon because I documented the process. When I opened the headphones up to open the vents by the 2mm or so and pulled the electrical tape off, the felt came off with it. So I took the felt off of the other cup and replaced it with tape, leaving a sliver of space open. I tried that out and there was still a very small amount of bass. It still sounded very weak, let alone having any thump. So, I took off the tape expecting bloated, but boomy bass... and instead I feel like I have decent to good bass now. Still not as much extension or thump as I'd expect though.
 

 

[wje]

Quote:Originally Posted by TK277 /img/forum/go_quote.gif


Correct. When I had the vents closed with the original felt and electric tape over that, they were very bright. I'll post pics of what I did the headphones soon because I documented the process. When I opened the headphones up to open the vents by the 2mm or so and pulled the electrical tape off, the felt came off with it. So I took the felt off of the other cup and replaced it with tape, leaving a sliver of space open. I tried that out and there was still a very small amount of bass. It still sounded very weak, let alone having any thump. So, I took off the tape expecting bloated, but boomy bass... and instead I feel like I have decent to good bass now. Still not as much extension or thump as I'd expect though.
 
 

About how many hours do you have logged on the 'phones?  

 

[bluemonkeyflyer]

I'm glad you were able to tweak the V8 mod to suit your audio chain and your SQ preferences. Everyone must take any given mod configuration and "make it their own" by tuning to match their equipment and personal preferences. Even when following a mod configuration "to the letter," there will be variations when measuring, cutting, weighing, and implementing all components that result in different SQ and measurements. For example, there will likely be discrepancies in density, thickness, and placement of cotton and felt used in a mod. There may be inherent differences between apparently identical sets of T50RPs, such as the type of driver dampener, that will require adjusting one or more components. 
 
FWIW, my audio chain: 
 
iTunes Lossless and FLAC Files > MacBook Pro > Glass Toslink > Dacmini (DAC and Amp duty) > Headphones
 
and
 
ITunes Lossless and FLAC Files > MacBook Pro > Glass Toslink > McIntosh MX-136 Pre/Pro > Dacmini (Amp duty, only) > Headphones
 
Quote:

Correct. When I had the vents closed with the original felt and electric tape over that, they were very bright. I'll post pics of what I did the headphones soon because I documented the process. When I opened the headphones up to open the vents by the 2mm or so and pulled the electrical tape off, the felt came off with it. So I took the felt off of the other cup and replaced it with tape, leaving a sliver of space open. I tried that out and there was still a very small amount of bass. It still sounded very weak, let alone having any thump. So, I took off the tape expecting bloated, but boomy bass... and instead I feel like I have decent to good bass now. Still not as much extension or thump as I'd expect though.
 

 

[wje]

D'oh.  OK, I just had a stupid moment that's been with me for awhile.  I've read of the use of "transpore tape" and thought it was some sort of tape used by the electronics community.  Well, thanks to Google, and a trip to my local CVS store, I now own a role of transpore tape, which is just surgical tape, for those who are like me and didn't know what it really was or where to purchase it.  

 

[Congo5]

Yes not easy to keep track of ...........All the products...
 
found this at Rite Aid: 3M Transpore Surgical Tape
you have to read the back for the hospital name..

I did not try it on the driver because if you try to blow through it----it seems very restrictive..
much more than felt, cloth.
 
getting another pair next week, may try some.. it will be nice to compare mine to stock and see the difference.
 

 

[nick n]

There is a difference between Transpore and Micropore. Transpore is the one you should shoot for.
 
Use it as a reflex dot over the center of the driver rear, anywhere from 2cm to under that according to tastes, only if you find the highs need bumping up that is. If not don't bother.
 
I used it upside down and secured with some thin tiny strips of double-sided tape along the driver rear support crossmembers. This way if it decides to get gummy, it will not gum up the stock white driver damping paper and will go into whatever you put on top of it for your dampings ( IE felts )

 

[bluemonkeyflyer]

Quote:

There is a difference between Transpore and Micropore. Transpore is the one you should shoot for.
 
Use it as a reflex dot over the center of the driver rear, anywhere from 2cm to under that according to tastes, only if you find the highs need bumping up that is. If not don't bother.
 
I used it upside down and secured with some thin tiny strips of double-sided tape along the driver rear support crossmembers. This way if it decides to get gummy, it will not gum up the stock white driver damping paper and will go into whatever you put on top of it for your dampings ( IE felts )

 
This is important if using any kind of tape directly applied to the white driver paper. I learned the hard way about adhesive residue from multiple applications altering the dampening. I wondered why my mods were producing such different results when it dawned on me that it was adhesive build up. This was not a problem, thereafter, because I adjusted other components to compensate. It's best to use nick n's method, though. BTW, in another discussion, geetarman also pointed this out to me and suggested using solvent to remove the adhesive from the tape before installing it onto the driver grid.
 
In another mod, I used rubber cement to secure felt to the back of the drivers. It reacted with the adhesive holding the stock white paper in place and caused a gooey mess that separated the white dampener from the driver grid. I don't remember what type of rubber cement I used, so be careful with various glues and tape. Thin strips of acid-free double-sided tape seems to work, so far, as does securing felt and other materials with tape around the perimeter of the driver grid.

 

[wje]

BMF,
 
For a pair of T50RPs that have had the grid / filter paper removed, what is the best approach for rebuilding?
 
- A coffee filter?
 
- A dryer sheet?
 
- The transpore process that you designed and documented under the Wiki pages?
 
Also, I'm assuming that once someone has restored the grid / filter paper, then the heavy felt is carefully adhered with the transpore tape around the edges.  Correct?
 
Thank you !!
 
Oh, for those who haven't gotten their hands on the transpore tape yet, to ease the modification process, please do!  That tape is miracle tape.  I found a nice little Fiskars scissors from my wife's un-used scrapbooking tool selection and "borrowed" it.  That smaller scissors is very precise and great for cutting the transpore tape into thinner strips for use in placing around the edge of the stiff craft felt on the rear of the driver, as well as some other adhesive processes.  I think the transpore tape is the "duct tape" of the medical field and electronics modification hobby. 

 

[KneelJung]

Quote:

BMF,
 
For a pair of T50RPs that have had the grid / filter paper removed, what is the best approach for rebuilding?

 
I know I'm not BMF, but I wanted to chime in. I had all sorts of material covering the grid with the stock paper still in place Wayne. A couple of different kinds of felt, some corduroy like stuff where one side of the fabric was flat and smooth, some t-shirt like material, that tweed stuff I sent you with the plasticine, and I'm sure some other things as well. I even tried some micro pore type paper which is when I ended up ripping the stock paper. Best mistake I've made with these things as I was reluctant to remove the stock paper. Anyway I did the dryer sheet, didnt much care for it. The tweed cloth I referred to earlier didnt work as well by itself, as it did in conjunction with the stock paper in place. That was my favorite configuration, and the one I was returning to until I inadvertently used to much glue, and ended up ripping the stock stuff when I tried to undo my recent experiment.
 
My most recent configuration, uses a silk or rayon type material to cover the driver grid. I think I'm done. I messed with them a little last night and removed and replaced the fiber fill pictured above, but ended up putting it back in. Not quite as much as what's pictured., but I dont think I'll be messing with the for a while

 

[wje]

Brian,
 
Thanks.  BMF has noted that there are actual changes to the physical properties of the paper on the back of the Fostex drivers that changed as of a few months back.  One was a bit more poreous than the other version.  One is apparently a bit harder to configure for the modification, too and more attention is needed with several adjustments to get things "just right".
 
I have a bag of fiberfill at home and is somehing I had used about 6 months ago.  I can't remember back that far, or actually what my results were.  I take lots of notes at work, but very few for the hobby.  I could give it a try again and see what comes of it.  Also, I was fortunate enough to procure one of the sound testers from BMF to use with the REW software.  I had procured the wrong jack yesterday at Radio Shack, but will get the correct one today to perform the tests to see the variance as the mods get tweaked a bit.
 
I did find some pure wool on Friday.  I guess I'll have to admit, I'm not very impressed with it.  Or, at least not nearly as impressed as the Rite Aid "Natural Absorbent Cotton" that BMF has recommended.  That stuff is beautiful in how it works.  Though, some pages back, BMF did elude to the fact that Rite Aid could have switched suppliers as the next batch of cotton wasn't as effective as earlier batches were.
 
Thanks for sharing your experiences, Brian -- more great information for all of us to take in and consider for the mods that we apply to try and tweak every last percentage of performance out of these wonderful headphones.

 

[KneelJung]

Quote:

I have a bag of fiberfill at home and is somehing I had used about 6 months ago.  I can't remember back that far, or actually what my results were. .

 
I've had different amounts of fiber fill in the cup before. Same basic configuration as pictured on the previous page, but without my blue fiberboard disc. Without the disc and just the fiber fill, the tone and timbre were OK, but they sounded kind of muddy. With just the disc, and no fiber fill, they would get get a little peaky in the upper mids. The fiber fill tamed that. The current configuration is my favorite. I dont really see any reason to open these up again

 

[Nevod]

Quote:

 
For temporary purposes while tweaking and measuring, I've used a little square of electrical tape to close the baffle port. For permanent sealing, I've used hot glue and silicone. They work equally well and are still reversible. Whatever you use should completely seal the baffle port and stand the test of time without shrinking, drying, or cracking. Tape is not a permanent solution. As it dries and shrinks, the baffle port will gradually open over time, changing the SQ ever so slowly.

I suppose that absolutely complete sealing of the baffle vent is not a good thing, especially when bass ports are sealed too. It's quite easy to make these phones really completely sealed, and sealed cup would mean that changes of ambient pressure would offset the diaphragm, also that would create 'vacuum' effect when quickly putting these on/off. I'd suggest leaving a tiny hole using something with controlled dimensions, like syringe needle, for example. That would move effect of the port away from sonic frequencies yet allow it to compensate atmospheric pressure changes.
 
 
Quote:

Half circular diffusors need lots of space around them to work properly, search for Volkmann on Policyndrical Diffusers, its all explained there. They may scatter the wave somewhat but I guess simple wool or material damping would yield more effects in a headphone enclosure.
 
Helmholtz resonators will be useless, headphones work slightly different than speakers, or maybe in other words, they work on differet air cavities. I can't see how you are going to stuff such a resonator into a headphone (bass absorbing resonator needs many liters of volume to work), not mentioning how do you know which frequencies you should cut.
 
Have fun

Can't really agree with the resonator case. Headphones act quite differently to loudspeakers on lows, as they belong in pressure mode and membrane displacement is comparable to volume attainable with Helmholtz resonators. The resonator's target frequency also depends on its neck size, and there have been calculations on this thread which indeed show that the resonators which were tried should be acting only way up in the higher frequencies, however, when operating on neck dimensions significantly lesser than target frequency wavelength, formulas get quite more complex as friction and air viscosity come into play and shift frequency lower. With the very thin slit-necks used frequency may indeed go all the way down to bass frequencies.