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

[hans030390]

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When I referred to "naked drivers" that was a misnomer. They are indeed stock drivers with the while paper in place, but no other flat materials laid directly on top. 
 
What materials have you tried so far? I've seen people recommend coffee filter paper and used dryer sheets. You might also consider using fusible interfacing (used in sewing) and various samples of lens cleaning microfiber. (I'm not harping on microfiber as anything magic, but it does come in a range of porosity.) If the material doesn't boost the top end enough, blow through it, then look for a material that is even harder to blow through. Or try a double layer of the material. 

 
Ah, I see. I've tried used dryer sheets before, but it's been a while. I was just curious if you had tried anything or not.
 
Any chance you could provide more detailed instructions with pictures on how exactly you used rockwool in your mod? I think I have a pretty good idea of what you did, but not exactly. Some pictures would really help!

 

[atl5]

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Anyone have any leads on where to get 003 pads?  (not the new HM5 mk2 pads)  Something was mentioned here recently, but head-fi search is so useless.  Feel free to pm if it's super secret

Was scanning around earlier today and came upon this on the FA-003 post, its a rebrand of FA-003 that comes with a spare earpad and for the price of $50 + $20 shipping.
 
Thread: http://www.head-fi.org/t/491632/review-fischer-audio-fa-003-a-neutral-champ/2355#post_8388452
 
Place to buy: http://www.jaycar.us/productView.asp?ID=AA2065&form=CAT2&SUBCATID=1015#4
 
At this price, I had to order myself one. 

 

[rhythmdevils]

Thanks for the tip.  That's kind of a lot to spend though not knowing which pad version they will come with.  Can you let us know which version they come with? 
 
My 003 mk1 pads aren't even on both sides anymore so need a replacement.  grrrr

 

[mink70]

Not sure this is the thread to post this, as it seems deep into technical modding info, but I picked up a pair of Fostex T50RPs a few days ago and wanted to ask a question. I'm new to orthos, having lived with dynamics--Grado HF-2, Denon AH-D5000s and 2000s, Senn HD-25s, and Ety HF5s—and I have to say I'm pretty astonished at what I'm hearing. After 20 hours of burn-in, the Fostex produce an effortless, wildly dynamic sound that has a kind of liquidity and drama I simply haven't heard before. This morning, I listened to Axis Bold as Love, an album I've never connected with all that much, and I was so moved that I nearly cried. The only problem--and it's vexing—is that the phones only seem to do this on SOME recordings. Others sound merely okay. On some, the vocals sound strangely muffled. (I'm driving them with a DacPort that's connected to a MacBook Pro running Apple Lossless and AIFF from a fast FireWire drive via Fidelia.) Why is the Fostex showing its magic only on some recordings? Is this to be expected? And what can I expect from modding?
 
Thank you, thank you.

 

[supramkivtt2jz]

I have not read through this thread completely, but I have noticed multiple channel imbalance issues. I have recently discovered my t50's also have balance issues, so I took the ohmmeter to them. 
 
Turns out the right channel is about 5 ohm more than the left. 
 
My left clocks in at approximately 56.2 and the right at 61.3.
 
To correct this, I soldered a 5 ohm resistor inline with the left channel between the input connector on the left side and the positive terminal on the driver itself. I do not have balance issues anymore. 
 
edit: by 5 ohm resistor, i mean by using two 10 ohm resistors in parallel. 

 

[Trance88]

Yep, I had ballance issues with my T50RP as well. That's why I traded them for a used pair of T20's. I think had I got a more balanced pair of the T50's, they would blow the T20 out of the water.

 

[Arleus]

mink70,
 
When I first got my T50RPs and listened to them, I was immediately struck by the muffled vocals you mentioned. The poblem with them, in their stock form, is that their frequency response is very midrangey, being pretty significantly rolled off through the upper mids and highs, and through the bass region (100Hz and down). They also have a lot of reflections flying around the inside of the cups, which can in some cases create a very lush, rich, midrange, but it can also muddy things quite a lot on other recordings.
 
Modding can bring, within reason, the sound that you're looking for. Personally I aimed for the flattest response possible between 20Hz and about 2kHz, and I aimed to clean up the reflections in the cups as much as possible. I'm running something akin to the current BMF mod, and the result is a very clean fast sound, with a wonderfully natural midrange. 
 
 
 
Quote:

Why is the Fostex showing its magic only on some recordings? Is this to be expected? And what can I expect from modding?  
Thank you, thank you.

 

[supramkivtt2jz]

Quote:

mink70,
 
When I first got my T50RPs and listened to them, I was immediately struck by the muffled vocals you mentioned. The poblem with them, in their stock form, is that their frequency response is very midrangey, being pretty significantly rolled off through the upper mids and highs, and through the bass region (100Hz and down). They also have a lot of reflections flying around the inside of the cups, which can in some cases create a very lush, rich, midrange, but it can also muddy things quite a lot on other recordings.
 
Modding can bring, within reason, the sound that you're looking for. Personally I aimed for the flattest response possible between 20Hz and about 2kHz, and I aimed to clean up the reflections in the cups as much as possible. I'm running something akin to the current BMF mod, and the result is a very clean fast sound, with a wonderfully natural midrange. 
 
 
 

 


What have you done differently compared to the newest BMF?

 

[Arleus]

Quote:

 


What have you done differently compared to the newest BMF?

 
For practical reasons I did things slightly differently to BMF - my mod configuration with measurements is back on page 540, post 8093. We think I have different driver paper to BMF, and since my 840 pads were sans dust cover, and earside felt was removed, I ended up with different mods. 

 

[micmacmo]

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Any chance you could provide more detailed instructions with pictures on how exactly you used rockwool in your mod? I think I have a pretty good idea of what you did, but not exactly. Some pictures would really help!

 
The mods I've been using lately all have the same basic configuration. The biggest differences between mods are the cup filling and the material I use to supplement the white paper on the driver. Here's what's common:

1. Stock felt on cup vents.
2. Stock white paper on driver back
3. Stock dust cover over the driver on the earside.
4. Stock baffle holes (one open, three closed)
5. Cup back: two strips of Acoustipack on the deepest sections of the cup bottom and 1-cm strips of Paxmate on the vertical walls of the cup. Nothing on the tapered outer section of the cup. I filled the groove in the cup that connects with the baffle with plasticine (the white ring visible in accompanying photo). This is probably overkill. You could probably use Paxmate throughout if you don't have Acoustipack.
6. Baffle back: compartments filled flush with tungsten. But plasticine is likely fine.
7. Baffle front: I sanded off the dustcover everywhere except over the driver. I covered the sanded area with B-Quiet (Dynamat equivalent) and covered it with adhesive felt. (The only thing covering the driver is the stock dust cover.)

 
As I mentioned, I bought cubes of Glodan rock wool from a hydroponics shop. I used an old picture frame as the cutting jig to get uniform 1-cm slices. (Note that the rock wool has a "grain" to it. I cut across the grain. The result is that, when the rock wool is installed in the cup, the fibers run perpendicular to the surface of the driver. I'm not sure if that matters or if having the grain parallel to the surface will perform better or worse.) The space between the glass and the frame was 1-cm exactly. I laid the rock wool on the glass and used the surface of the frame to guide the serrated blade of a bread knife. BMF used a fancy bread knife with a laser-guided incision system, I think. : )
 

 
I used a knife to cut a 1-cm-thick slab to fit the back of the cup and accomodate the hanger hump. (Here's a google docs link to a pdf scan of the rough template I used. The dimensions of the printed template should be 5.6 cm x 6.8 cm.) Don't forget to punch out a hole for the hanger hump. Once I had the hanger-hump hole cut out, I took the plug and I cut it to half its thinkness. Here's the result.
 

 
 
And here's the plug re-installed into the hole. Note the dents and divots where I pushed the cup posts into the rock wool.  
 

 
And here's the rock wool installed.
 

 
On the driver, I used two-sided tape to hold in place a 4cm x 4cm piece of (orange) microfiber material cut from a lens-cleaning cloth. 

 

[hans030390]

Awesome, thanks!

 

[Armaegis]

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On the driver, I used two-sided tape to hold in place a 4cm x 4cm piece of (orange) microfiber material cut from a lens-cleaning cloth. 

 
Um... if you used two sided tape, doesn't that mean you have plastic tape directly behind the driver? the microfiber wouldn't matter in that case.

 

[Armaegis]

edit: double post

 

[sluker]

Not if it's just around the edges.

 

[micmacmo]

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Not if it's just around the edges.

Roger that. The tape's sliced nice and narrow and stuck just around the periphery of the driver opening.