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

[applepancakes]

from bare drivers on both sides:
-glued coffee filter on the back, used a pin to make a hole through the coffee filter to get more bass
-sandwiched pink insulation between stiff felt on the earside (to get rid of excessive 2.5k+)
(also recabled, plasticine flush, hm5pads)
 
sounds decent now. some channel imbalance. were i to do it again, i'd leave the stock felt and work from that.
 

 

[rhythmdevils]

Quote:

-glued coffee filter on the back, used a pin to make a hole through the coffee filter to get more bass

 

 
Where did you read about this?  It's eerie to see something I came up with but never mentioned in this thread recited as if it were common knowledge...  not a big a deal, I'm just curious...

 

[applepancakes]

i mentioned it before. naked, the bass was too much. with the filter it was close but the hole i added helped. (and only the insulation on the ear side helped with the treble)
 

 

[kalbee]

Quote:

I got my t50rp a while ago but work has been eating up all my free time. I hope to put my days of next week to finally doing some mod
Kalbee -. Your post is exactly what I was looking for. Is there a list of mods and what they do? I am a total nood to this stuff. Heck I don't even know what a baffel is. Are there any pics to give me a better idea how to do these mods.
My main goal is to make them good for metal. Preferably simple to do mods. That or make them good for movies with deep powerful sub/bass and good mids like hifiman if that is even possible.

Baffle is the rigid piece where the driver is attached on (also the earpads, in some cases, but not stock on the T50RP). Took me a while to figure out what it was also; I think it was the same post that jgray linked (first link in http://www.head-fi.org/t/452404/just-listened-to-some-fostex-t50rps-today-wow/8190#post_8378064) that taught me it.
 
Pretty sure there are posts that describe what kind of mod does vaguely what kind of changes to the sound. Unfortunately I did not save the links to the specific posts so I can't share them with you, nor do I remember them well. I just try different things. The only things I do remember are mass loading (as in to increase the weight of) to reduce plastic resonance (not always a big issue imo) and the use of fiberglass/cotton/etc. inside the cups to trick the return waves into a larger cup volume, increasing soundstage (but also changes the overall sound). If I remember well, fiberglass works well to bring out some bass also...?
In any case, here's a place to get started: http://www.head-fi.org/t/571549/fostex-t50rp-modification-summary-links
Also the stuff that jgray linked previously.
You can also look at various mods done on just about any headphones or speakers and, if there are explanations given, the same or with variation should be applicable to mod your T50RP.
 
 
If you want them good for metal, depends if you want your headphones to be as transparent as possible or to put emphasis on specific sounds. As far as mids go I kind of liked it best stock, or at least with stock pads... bass is a problem with those though.

 

[Nevod]

Where did you read about this?  It's eerie to see something I came up with but never mentioned in this thread recited as if it were common knowledge...  not a big a deal, I'm just curious...

It was mentioned in ortho thread a few years ago as "differential damping", but I don't remember who was the author. Maybe it was you.

 

[rhythmdevils]

No that was Ludoo and Kabeer.  This isn't exactly differential damping.  That refers to different damping on different parts of the driver and was developed around the pinched Yamaha driver whose center acts different than the outer edges of the driver, it's kind of like a ring radiator.  This is more like "vented damping" or something.  It's just funny how stuff finds it's way in here.  You guys are an eager bunch!! 

 

[DeathDomokun]

I remember seeing a post on another forum regarding poking holes in the paper covering the driver, it talked about where to poke the holes with a picture of a naked driver so you can see, as well as explaining to poke one hole at a time.

 

[OperatorPerry]

Can someone please post the dimensions of the driver/ driver PCB assembly thing?  I need to get them to jschristian so he can make baffles for me.  Will foam board baffles be okay?
 
Perry

 

[kalbee]

Baffles in general should be rigid. Foam board will only be rigid at much greater thickness so it really isn't recommended IMO. But if he is making something for you, don't think any dimensions we can give would serve you any good... It's gonna be custom...

 

[OperatorPerry]

Quote:

Baffles in general should be rigid. Foam board will only be rigid at much greater thickness so it really isn't recommended IMO. But if he is making something for you, don't think any dimensions we can give would serve you any good... It's gonna be custom...

If I give him the dimensions of the driver he can cut the holes and stuff for me.

 

[bluemonkeyflyer]

Is anyone interested in a measurement kit compatible with Room Equalization Wizard (REW) and Windows/Mac's? I have two. Included will be the phantom power supply that operates on a 9-volt battery and 1 wired Panasonic electret mic (WM-61A) that goes in your ear and takes into account your personal ear shape during measurements.
 
The phantom power supplies are ready to be installed in tea tins. They are identical to the one I copied from wdam519 and pictures are available in the WIKI under BMF V8.1 Mod. The links and tutorial for  setting up and using REW are listed along with the other WIKI documents.
 
I'll send them out for my cost of $35.00, including shipping in the CONUS. Shipping outside the U.S. will be approximately $20.00 more, or $55.00 US, total. I will charge exact shipping and let you know the total before you send any money via Paypal.  I am not profitting.  I made the kits simply for the fun of it and want to make them available to the community because I've found a measurement kit so useful, myself.  I will send them out Only to people who do not have a soldering kit. If you know how to solder, make your own! It's easy.
 
I have tested the measurement kits and they work. I will re-test before shipping. If your kit does not work when you receive it, you can send it back to me for a refund not counting shipping.
 
It would be great if, after you're done modding and measuring, you would make the kit available for someone else at cost plus shipping.
 
If interested, PM me.

 

[geetarman49]

kudos, BMF!

 

[Nevod]

Quote:

No that was Ludoo and Kabeer.  This isn't exactly differential damping.  That refers to different damping on different parts of the driver and was developed around the pinched Yamaha driver whose center acts different than the outer edges of the driver, it's kind of like a ring radiator.  This is more like "vented damping" or something.  It's just funny how stuff finds it's way in here.  You guys are an eager bunch!! 

I recall it was indeed about using an damper disc with cut-out where another, less dense damping material was to be inserted, but it was also suggested to pinch a hole through the dampers for the ones who carved more bass. Maybe it wasn't the first post though, maybe it was a requote.

 

[kalbee]

Quote:

If I give him the dimensions of the driver he can cut the holes and stuff for me.

Oh woops. That's what you wanted. Well considering you will most likely want to keep the driver in it's original plastic enclosure, you'll probably only need a cutout of 1 3/8" square, which is essentially the size of the steel(?) plates that sandwiches the magnets. The rest can be screwed onto or glued onto the baffle or something. Not 100% sure of how the unit looks like so I can't tell you the actual size and shape; do take note it's a irregular shape. Assuming you have a T50RP (or T20/40RP) you can take it apart and see it for yourself; my mods are still fully reversible and so I have yet to dislodge the drivers from the baffle to see if there's any indent towards the ear-side.

 

[micmacmo]

One isotope of Unobtainium I've wanted to get my hands on for awhile is rock wool. Joelpearce mentioned it many months ago as a cup dampener and said he had it leftover from a construction project. It turns out that it's not just sold in bulk for construction but also commonly used in the plant nursery and hydroponics industry as an artificial "soil" for germinating seeds. 
 
I went to a hydroponics shop in town (I now know where marijuana grow-ops get their equipment) and picked up some 3-inch and 4-inch cubes of rock wool. Cheap. It's made by Grodan with a 70 kg/m^3 density (vs the Roxul Safe'n'Sound fiber Joel used with its 40 kg/m^3).
 

 
 
I cut 1-cm-thick slabs and cut them to fit into the bottom of the cups and around the hanger "hump," thusly:
 

 
I tried the rock wool with various materials on the back of the driver (on top of the stock white material). The only effect of these over-the-driver materials was to enhance or decrease the mids and treble, from about 1 kHz up (no effect on lower mids or bass). Plush microfiber (from a dusting cloth) gave the brightest sound, then, in descending order, thin/smooth microfiber (from a lens cleaner), dense cotton (from a nursing pad) and stock material alone.
 
The thin microfiber with the rock wool gave the flattest frequency response and, to my ears, the most pleasing sound. 
 

 

 
(Note the apparent "ridge" at 60 Hz in the heat graph. I'm not sure what that is but it's consistent across all my mods involving rock wool. I can't hear it, though. Maybe that's why Purrin truncates his amazing waterfall charts to ignore the lower end of the spectrum?)
 
This mod measures similarly to my mods involving absorbent cotton in the cup and plush microfiber over the stock white driver material. However, I think this sounds a little more open (although I'm not sure what I'd need to measure to convince myself that it is truly so! 

 )   I'll stick with this mod until I find some fault with its sound and start mod'ing again.