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Just listened to some Fostex T50RPs today... WOW! - Page 293

post #4381 of 10873

wdahm519,

 

You make good points based on sound observations. As I mentioned, my post was based on a bunch of "if's": if we used  -->   the same amount of cotton, teased to the same density; the same equipment; the same amount of Dynamat; the same amount of acoustic foam (not to mention different brands of acoustic foam); the same amount of putty (not to mention the density/weight/damping differences between commercial plasticine and my formulation of tungsten putty). There are obviously multiple variables interacting that create the perceived differences that we/every individual "hears" - then there is our different HRTF X preferences X biases*cognitive dissonance to consider. I am no more immune to placebo, confirmatory bias, and/or cognitive dissonance than anyone else. 

 

I will try what you suggest and let you know what I "hear." beerchug.gif I hope you, and everyone else reading my posts and this wordy reply, appreciate that my impressions are nothing more than my impressions and sonic preferences. To me, it's all good. I share my experiences and impressions FWIW, IMHO, My 2 cents, YMMV, etc., for others to try or toss in the waste basket. I know what I like when I hear it; same as everyone else, and understand that what works for me may not work for anyone else. I do not deign to pass judgment on your work and results, or anyone else's.

 

Peace, cheers, and best to all,

 

BMF
 

Quote:
Originally Posted by wdahm519 View Post

BMF,

 

I find what you say interesting.  I will try and test with no cotton in the cups so ONLY the electrical tape reflex dot this weekend and see what I think.  I'm really busy this week and don't have time to do it until Saturday or so.  However, I found what you said true when comparing amps.  My Bijou tube amp makes the mids sound fuller and gives the bass some added presence where as my little Total Bithead is not up to par.  It leads to thinner sounding mids and slightly weak bass.  

 

I'm very happy with the balance of the cotton in the cups with tube amps, but I'm also a big fan of tube amps.

 

 

Also, I used less cotton than you did per that picture.  My cotton was way thinner.  The Jumbo balls are bigger than the Triple balls, at least here in the East Lansing, MI Kroger where I bought the cotton balls.  

 

Try thinner cotton and let me know as well what you think!



 

post #4382 of 10873

First one of you to make a how-to video on this would get a ton of hits.  Amazon's suggesting blu-tack and other mod materials along with the Fostex T50RP.  tongue.gif  

post #4383 of 10873

 

Here is a translation of a post on Russian forum regarding modding T50RP's. It's not my post, so I wouldn't comment  much on it.
 
 
 
And so I, having done an immeasurable amount of mods to T50RPs and still getting the same result, came to a conclusion that they can't be helped only with damping and their sound cannot be improved without modding the driver itself. In my opinion, their driver construction is flawed, while the membrane is of very high quality, albeit small. The effect a grille puts on the sound has been discussed there, and well, what we have with that driver? Fostex has saved up on magnets, put only 3 instead of 5 and replaced the others with metal plates which have 42 holes 2mm diameter each to pass the sound. Total equivalent area of these holes is ~132 sq.mm, which equates to a single 13-mm hole, about 15% of the membrane's surface. Also, the holes are so small, they're smaller than the emitted sound wavelength. I kind of remember from school's physics that it results in wave being emitted from one point with a spherical wave front. It's called diffraction IIRC. Then these waves sum up with different phases in different locations, and that's called interference. And more than that, sound is trapped within two bare metal plates and reflects from them multiple times before getting out. No wonder Fostex's sound is so sloppy, weak and muddled and is so different from other orthodynamics.
 
So, I've lost my temper and being on vacation, I've decided to do a radical driver mod, which was planned long ago. The result was as expected. I've tried two versions of modding, easy and complex. Easy method uncovers 100% of driver's area, complex - about 50%. Easy method is inspired by construction of HE-4, the magnets from one side are just completely removed, and the driver is damped on the back till proper tonal balance. Sensitivity is reduced indeed, but just by about 30%. Sound becames just like the proper isodynamic sound, with deep and mighty bass and clean and clear highs. It would be perfect if not some boominess. Hard to say what it's due to, perhaps because 
 
there is some space where there were magnets, which makes a chamber of sorts. Perhaps it's possible to correct by making membrane closer to ear, but it takes a complex and irreversible modding of driver's enclosure. I'm not yet ready for such an experiment. So, I've modded the front magnets, by removing metal between holes in the front metal plates. I've left only 4 "joints" - in the corners and underneath the plastic grid. It was a tedious job, using thin drill and needle file (may be wrong translation), but it took only one evening. Used cotton wool to remove remaining metal dust from drivers. Modded magnets should be glued back properly so that they won't jump out and damage the membrane during reassembly. Be very careful during assembly\disassembly and remove anything metallic away.
 
I have also covered the gaps between rear magnets completely with thin 1mm natural leather to reduce reflections. 
I've left one hole in the center to further tune the damping. Damping is a theme in itself and depends on wether 
you've removed stock damper, on materials etc. and is done by ear. One thing is sure - damping should be quite 
heavy, or there would be too much of boomy bass and echo. Anoter mod is spacer for earpads made out of polyethylene 
foam 3mm thick. Ear just barely touches the grid then and sond becames fuller to my taste. 2 layers is completely 
comfortable, but there's too much bass that way. After the modding, the phones sound completely different, very 
interesting. Very deep and mighty bass without distortion and midbass peak. Slight recession on low mids and a rise 
on upper mids, so they sometimes "shout" on wind instruments and high vocals. Highs are very extended, clean and 
sparky - a typical orthodynamic. Reading LCD-2 and He-5 reviews, I think I've got something inbetween them for much 
less money. Photos follow.
 
 
Comments before photos.
 
The improved driver from the front. I've left "joints" in corner as membrane barely moves there and they don't play 
much role in sound.
pic1.jpg
 
 
Rear magnets with plates covered by natural skin, view from membrane side. Only 2 holes are left for further 
damping.
pic2jpg.jpg
 
Rear magnets from rear. One of the left holes is taped over from that side, as pleather earpads required more 
damping. Damping can be tuned further by covering remaining hole with duct tape. I've covered about half of the hole 
to get tonal balance for me. 
pic3.jpg

 

 

 
If the holes won't be covered, driver should be damped in a traditional vay, by covering it with dense felt. Like 
that, or like as in the Thunderpants.
Here,a 2 mm hole is punched in the felt, and a piece of plastic with 1.8 mm hole is glued over. That hole in the 
plastic can be further taped over. If it's not covered, the balance seems to be like LCD-2s, bassy and a little 
boomy. The more damping, the more highs and less bass and boominess. With optimal (for me) damping, sound is very 
detailed and natural. I can't call it very open, as the headphones are almost completely closed. But there's no 
effect of in-head localisation, sound comes from the front. That, combined with deep bass, creates an illusion of 
being in cinema when watching movies. If the stock paper damper is not removed, damping should be done differently, 
covering driver's rear partially with felt, for example.
pic4.jpg
 
I must note that everything has been tuned with 3mm earpad riser. It changes the sound noticeably. If there's no riser or a different riser, damping should be also changed.
Also, cups are covered with thin skin on the inside and filled with synthetic fibers (sintepon). But this is a leftover from previous mods and barely changes the sound. Most of effect is from opening the drivers. Besides that, in an attempt to reduce bass and boominess, I've drilled 3 more baffle vents 2mm in diameter in addition to one stock. They are placed in 3 remaining corners. hard to say how they effect the sound, but it seems that compression on the bass has been reduced. 
pic5.jpg

 

post #4384 of 10873

yeah, enough w/ the sissy cups damping....let's saw and mod the friggin' drivers already evil_smiley.gif

post #4385 of 10873

I would need to read a serious amount about those in order to consider doing that, and if at all it would be with a second pair. Nevertheless, that's pretty cool.

post #4386 of 10873

Yeh, looks like another pair may be on the way, time to hack into the drivers,.....muhuhahaha wink_face.gif

post #4387 of 10873

It's getting too complicated blink.gif I'm just enjoying my stock T40 + 2pads w/ the Dared MP5 for now biggrin.gif

post #4388 of 10873

My 840 pads came from Amazon today along with my Patricia Barber CD, but I cant seem to be able to get them to fit. Is there a secret to putting these things on confused.gif

post #4389 of 10873

Mine came today and I did get them on, although it was a challenge. Just move around the cups and eventually you'll get there... Although I wouldn't want to redo this more than 2-3 times beacause it risks the pads stitching snapping/breaking.


Edited by Hennyo - 11/1/11 at 8:46pm
post #4390 of 10873

 Russians!!! lol thats cool!

 

M

post #4391 of 10873

Wow, I just got to the point where the tonality of these things is *perfect* for me. I listen to it and don't want to change a thing. Great bass extension, perfect amount of treble, awesome midrange tone, and very, very smooth.

Only thing wrong is I'm getting a little midrange reverb, probably because I'm using felt instead of paxmate, but damn, how satisfying.

post #4392 of 10873

Yea, my assumption is that felt would be more bassy than paxmate or the like.. I'm really craving sub-bass in these, but other than that they're alright. I just finished mrspeakers 840 cullimnation on page 285. Really not bad, and wicked fast. This is probably one of the fastest headphones I've ever heard, (I'd need to hear some Staxen side by side). But man, these are fast. I'm playing with the cotton thickness (Using Jumbo bawlls ;() but so far on first attempt pretty good. Mids / high end is perfect... I really like the high end. Very fast without any flaws I cn see, and it looks like his graph supports that. Might try another electric tape reflex dot, but quite good. Thinning out the cotton some more. Maybe space the pads a bit further away (elevate them some more) and that will create more sub-bass..

 

The Russian guy has a point. Most definitely BA what he's doing. I wonder if fostex tuned the magnet plate/'shield' that way on purpose though... To give it a more cohesive(?) analytical sound that the lcd doesn't have. (That is the lcd = different in the way it analyzes the sound... qh (Questhate) kind of summed the difference between the two drivers presentation of detail on page 246 or something...

 

btw, Sankar(!), if you're reading this thread, HI!

 

 

biggrin.gif


Edited by Hennyo - 11/1/11 at 9:13pm
post #4393 of 10873

I too wonder how would these milled drivers sound if they are to be coupled with properly mass loaded and foamed baffle and cups. Plus some bass ring damping..

post #4394 of 10873

Quote:

Originally Posted by KneelJung View Post

My 840 pads came from Amazon today along with my Patricia Barber CD, but I cant seem to be able to get them to fit. Is there a secret to putting these things on confused.gif


Just give them a chance to stretch out a bit. After taking mine off several times, I would say they are even easier to put on than the stock pads.

 

I have finally finished my major project of the past few weeks. Now I don't see many mentions of recabling around here, but I am really happy with how mine turned out. I was honestly never a huge fan of the single termination and wanted to go to something more traditional. I would up using 24ga silver plated copper silicon wire covered in 3mm nylon rope. The four wires are braided using a flat litz braid and the cable is terminated in a 1/4" Neutrik jack. Overall I am very happy with how it turned out. It sounds great and looks even better to me. The biggest problem of the whole ordeal was feeding the bare wire into the jacket. Once that was done, it was just a matter of getting my girlfriend to braid the wires for me and drilling some holes for insertion into the cups.

 

Even though the cable is now substantially thicker than the original cable (to be expected with four wires now), the cable is still just as flexible as the original. This was very important to me after comparing the stock cable to a recable I performed on my Grados using some Mogami Mini Quad, which is about 3x stiffer than this silicon wire.

 

Sadly my main computer is down with a whole host of problems I have been working through tonight, but hopefully I will be able to get some pictures posted up in the next few days if anyone is interested.

 

post #4395 of 10873
Quote:
Originally Posted by KneelJung View Post

My 840 pads came from Amazon today along with my Patricia Barber CD, but I cant seem to be able to get them to fit. Is there a secret to putting these things on confused.gif



Maybe try flipping the flap inside-out then wrap it around the edges after placing it on the baffle like that?

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