Just listened to some Fostex T50RPs today... WOW!

[bluemonkeyflyer]

Speaking only for myself:
 
The dust cover is very thin and loosely woven. I removed it on one set of mods and heard no change. Then, again, others have. I hear nothing above 15k Hz. Maybe removing the dust cover opens things up above 15k.
 
The stock white driver felt is part of the design. Remove it or work with it. I've done both. I prefer to keep it there and work with it. That said, IF you end up removing, try to carefully remove it with acetone and X-acto knife so you can re-apply with rubber cement if you want to go back to stock. I have done this twice. With your preference for more treble, and if you remove the white driver material, I think you might be pleasantly surprised what you hear with Transpore tape over naked drivers. To ME, 1 layer has too much bass, 1.5 layers is the sweet spot, and 2 layers further reduces bass quantity and further enhances treble sparkle.
 
You could try a reflex dot on the center grid overlaying the white material. Be careful if you remove it. I made a little tear in the white material once. I used a furniture bumper from the same pack I had used before and removed a dozen times without incident. You might want to press the reflex dot adhesive to a shirt sleeve or other material to remove some of the adhesive before sticking it on the grid.
 
You could try:
 
1. reducing the amount of plasticine and/or acoustic foam to free up more cup volume.
 
2. a different quantity, density, and type of filler vs no filler in the cups.
 
3. covering some of the bass port vents.
 
4. "limp" vs stiffened felt over the white driver material in various configurations and/or layers
 
Edit:
 
5. roll up a Kleenex tissue to make a paper "rope" and place under back half of pads; try smaller vs larger (length and diameter). This is the easiest mod and can make a big difference in sound quality. I previously gave my opinion that I heard no difference between stock pads and 840 pads.
 
 
 
Good luck and report back what you find.
 
Quote:

Disclaimer: I want to just stress that these are great sounding headphones. I'm mentioning only the flaws in this post
 
About the drivers, I was actually getting close to coming to the same conclusions the other night. I've still been trying to track down the source of this 1k resonance that's been plaguing my build. I removed the cups, and pressed the baffle and pad against each ear so that I was essentially listening to a completely open headphone (it wasn't comfortable - I had to hold my head right against the desk!). It essentially sounded the same, with the same problems as when I had the cups on. Good news there is that the foam, mass damping, and cotton wool I had in the cups is doing its job, and essentially providing little by the way of reflection, which goes some way to explain the quite open sound I have. The bad news is, the 1k resonance was still there, the slight muddiness and congestion was still there, and the lack of treble extension was still there. It's not a great test, because you could easily argue that the driver isn't supposed to work in an open design, but since the flaws are essentially the same with and without the cup, I think it's fair to hypothesise that it is the driver / housing / baffle for the moment. 
 
Now, a couple of things about my build - I've still got the stock white fabric on the back of the driver, and the stock black fabric on the ear-side. I'm slightly nervous about removing them, as it would take my build over the line, and into irreversible territory, and I'm not sure how easy it is to get equivalent fabrics in my area. I imagine removing that black ear-side felt will open up the sound somewhat?
 
Am I the only person noticing these 'flaws' (or characteristics, if you will) of the sound? If that's the case, I probably need to change my build. Or, do we think it might be inherent in the design of the driver / housing? Or, as another option, is it an issue with the pads (I'm still using stock, though I believe BMF stated they sound the same as 840, a few pages back). Or, is it simply the headphones I'm comparing to? You can see from my signature that I tend to prefer fast / analytical / sparkly sound signatures. I love the lush richness of my T50rps midrange, but do I have to sacrifice that to obtain the other qualities I enjoy?

 

 

[snakeeater69]

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2nd, I saw LFF's subtle hint at dispersion many posts ago and since his success is the center of much speculation I am inclined to investigate. I have a material in mind that is a natural vegetable celullose that has many random cells of differing sizes, so far it shows great promise (in my simple test) for really evening out the cup resonances without completely filling the cup or covering every surface (don't worry, whether it works or not I will share). In my stock cups I put a slice of this material in without any other material or mods and effect was immediately noticable, smoother coherance across the spectrum. I feel like this one simple step took me about 50% towards where I want to be. But I can still hear the plasticky honk from the cup, though already reduced.

 

 
Were you referring to something like Loofahs & Natural Sponges. I'm definitely going to try something these after trying the cotton balls to see if there is a difference.

 

 

[Hennyo]

This is what I was thinking too. ^ Augmenting sub-bass in these in the main problem. 20/15-45 hz. You need cup-space. I'm thinking cotton swabs and certain types of felt.
 
Mrspeakers mods are amazing in their own way though. They are dang fast. Very quick response.The latest iteration has exquisite mids and highs, balanced mids/highs and very well placed. But sub-bass.. Oh it's got me reelin'.
Hmmmm

 

[snakeeater69]

^Oh, I'm pretty much set on doing the latest RastaPants 2 by Mrspeakers. I just might try it with that material to see if there is any improvements. I highly doubt it though. One more day until my T50RP gets here. I hate waiting.

 

[dogwan]

Quote:

 
Were you referring to something like Loofahs & Natural Sponges. I'm definitely going to try something these after trying the cotton balls to see if there is a difference.
 
 

Yes, I was referring to Trader Joe's pop up sponges. They come compressed so you can slice them along an edge while they are still in that state. You wet them to make them expand. I was able to make 1-2mm slices this way. I'm sure they are also available at other stores undeer different names.
 
They are supposed to me made from 100% vegetable cellulose. The neat thing is that when when sliced that thin they have virtually no closed cells. And the size of cells is completely random.
 
Be sure to let them dry out before using in your cups. They will dry out fairly stiff, but I've found that if you put them in at just the point of being just this side of perfectly dry you can mold them pretty easily.

So far my results have been encouraging. I'm just coming out of Mid-terms though and have not been able to put much time into it.
 
I'm thinking that first I will try some really loose polyester batting in the cup, just enough to press a slice of the sponge up against the driver. Since my driver cups will already be damped with Quiet-Kote I'm thinking I will want the dispersion effect right up against the driver. My theory is that this will increase the damping of the driver diaphragm tightening up the bass while at the same time dispersing the reflected back wave from leaking back through the driver. Still just a theory.
 
Alternatively I may try them as dispersing pads in the bottom of the cup.
 
See told ya' I'd share.....whether or not it works.
 
-Dogwan
 
BTW,  just aced my PHY121 mid-term!
 

 

 

[Hennyo]

Quote:

 
-Dogwan
 
BTW,  just aced my PHY121 mid-term!
 

 

Hey, cool idea. What did you use to paint your cups? Btw, Right on Mr. Ace!
 

 

 

[dogwan]

Quote:

I need to find one of those rubber stoppers you used!  The only solution I could come up with is using silocone to hold the cables in place.

There's an electronics surplus supply store here in Portland. It's in a crapty part of town inconveniently located. But $10 will get you all kinds of little hard to find items. IRC those grommets were about $.05 each or 25/$1. I always find stuff I didn't know I needed. Last time I found an assortment of Orange drop 716's for $.25 each (NOS). And if you need odd tube sockets, they have 'em.
 
Anyway, I would look in your town for something like that. There's always someone making a living from this kind of stuff.
 
-Dogwan

 

[dogwan]

Quote:

 
What did you use to paint your cups? Btw, Right on Mr. ACE!

 

Quiet-Kote from CascadeAudio products. It's used mainly for car audio but has many other uses. I used it dampen the platters on 2 AR turntables with great success. Set up a rotating jig to keep the spray evenly balanced and applied 6 light coats. Did wonders for those notoriously ringing AR platters.
 
You can order it from PartsExpress. But I would probably just ask at a custom car audio place if the have an almost empty can for a pair of headphone cups.
 
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=268-250
 
PS; there are other similar products out there. This just happens to be the one I use.
 
-Dogwan

 

[rhythmdevils]

It occurred to me that it's a bit of a waste to be adding mass damping to an ortho, it would make for a better sounding headphone if the necessary mass (or as much weight as was possible for the comfort you want) was added via bigger driver and/or bigger magnets.  Of course we can't make our own drivers very easily, just a random thought. 

 

[Armaegis]

Quote:

It occurred to me that it's a bit of a waste to be adding mass damping to an ortho, it would make for a better sounding headphone if the necessary mass (or as much weight as was possible for the comfort you want) was added via bigger driver and/or bigger magnets.  Of course we can't make our own drivers very easily, just a random thought. 

Well the heavier the housing, the more stable and cleaner the response from the driver... yes a heavier/stronger magnet would be more ideal, but we work with what've we got

 

 

[vafan13]

has anyone tried damplifier pro, as opposed to dynamat xtreme?  It's significantly denser/heavier but only a bit thicker.  One of my friends is a car audio buff and says it is better.  General search of car audio forums seems to agree.

 

[mrspeakers]

Quote:

It occurred to me that it's a bit of a waste to be adding mass damping to an ortho, it would make for a better sounding headphone if the necessary mass (or as much weight as was possible for the comfort you want) was added via bigger driver and/or bigger magnets.  Of course we can't make our own drivers very easily, just a random thought. 

The mass is to reduce the resonances of the plastic.  Heavier magnets or bigger driver would not affect this.  It's cheap plastic that rings like a bell, and the mass loading reduces the resonant frequencies and decreases the amplitude of the resonance.  A big driver, of course, reduces the amount of plastic, but then you have an LCD-2.  
 
 

 

[rhythmdevils]

Yeah I was wondering whether there is a difference between mass loading the driver itself, or the structure around it, and it seems to me like the heavy magnets in a bigger driver would do just as much, but it would be reducing resonances closer to the source. 

 

[mrspeakers]

It still wouldn't solve the problem of the plastic "ringing." Damping serves two purposes; absorb energy in the plastic and lower the resonance.  Heavier driver/magnets would lower the frequency of the primary resonance mode of the structure, but it wouldn't damp out the vibrations that do occur in the plastic...  Also, heavier drivers have poorer high frequency response (in general)...

 

[sharkz]

As promised, here are a few pictures of my recable. Sorry for the lack of sexy pictures. Even though I have a nice camera, the lighting in my room is mostly terrible and I just don't have the energy to stage a proper photo shoot at this point.
 

 

 

 
If anyone has any questions, just let me know.