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Fostex T50RP Incremental Mods and Measurements - Page 151

post #2251 of 2259
Thread Starter 
Quote:
Originally Posted by dmillz4dayz View Post
 

I tried that and unfortunately it didn't help. In fact, I now can't get a connection between the leads. I'm guessing it's the break on the left blemish. Is there a way to bridge that gap? Maybe carefully tape it off and paint a conductive material over the break? Or would that mess with the impedance? 

Looks like you may have a small puncture on the lower left side and the lower middle section. If so, adjacent traces may be shorted. Difficult but not impossible to repair.

post #2252 of 2259
Quote:
Originally Posted by dmillz4dayz View Post

I tried that and unfortunately it didn't help. In fact, I now can't get a connection between the leads. I'm guessing it's the break on the left blemish. Is there a way to bridge that gap? Maybe carefully tape it off and paint a conductive material over the break? Or would that mess with the impedance? 

If you have lost continuity there is no practical way to repair the driver....
post #2253 of 2259

I'd like bring out vocals and guitars more on my MK3's. Would mods directly on the backside of the driver help with this? I'm not too sure what those mods actually do to the sound signature. Are they easily reversible? I'm afraid damaging the stock white dampening on the driver if I stick felt on top of it and then try to remove it if I don't like how it sounds. 

post #2254 of 2259
Yep, that's the way to go. Just don't stick anything onto the dampening paper, stick it around, over the driver assembly. I'd try to get my hands on stiff felt and a hole puncher, I'd try a square of 2mm stiff felt with a hole punched, aligned with the hole on the stock paper. This will reduce the bass as well.
post #2255 of 2259
Thread Starter 
Quote:
Originally Posted by xtenglong View Post
 

I'd like bring out vocals and guitars more on my MK3's. Would mods directly on the backside of the driver help with this? I'm not too sure what those mods actually do to the sound signature. Are they easily reversible? I'm afraid damaging the stock white dampening on the driver if I stick felt on top of it and then try to remove it if I don't like how it sounds. 

Read page 1 in this thread for numerous ideas to try, a description of the typical results from various modifications, and tuning tips.

 

Note: these mods were applied to T50RP mkII, not mkIII. Trial and error testing of these methods with mkIII will be necessary given the changes Fostex made to mkIII:

 

1 of 9 rear grids has the white paper cut out

controlled venting of the baffles 

venting on the ear side of the baffles via side slots where the lip of the pads are installed

 

 

Do not apply tape directly on the white dampening paper. If you do, the glue will eventually liquify and foul the white paper's damping properties. Instead, temporarily secure the felt with strips of tape around the perimeter forming a "picture frame." This is shown on Page 1 and this method is totally reversible. Once you settle on a modification scheme, you can permanently secure the felt over the back of the driver with a bead of hot glue all the way around the edges of the felt and driver frame.

 

Stiff felt seems to work better than soft felt. If you don't have stiff felt, try a double layer of soft felt.

 

I don't think plasticine, Newplast, or Dynamat are worth the expense and effort and they are difficult to remove.

 

The most bang for the buck sound quality modifications are:

 

pads

modifying the 4 cup vents

adding various dampening materials including cotton, felt, fiberglass, wool, and/or rockwool


Edited by bluemonkeyflyer - 12/4/16 at 11:29am
post #2256 of 2259

Are the drivers prone to rattling for deep bass, or is it mainly for the MK3 now that they cut out a grid on the driver allowing more air to move? I've had an issue with my left cup rattling and a bit on my right when the volume is turned up. I just exchanged it but the problem is still there. I just tried loosening the screws and tightening the screws holding the driver together. It helped a little bit, but the problem is still there. I'm using an O2/ODAC, no gain, and the rattling starts before I'm in the 12 o'clock position. Would Newplast around the drivers to hold down any direct vibrations help?

post #2257 of 2259
Thread Starter 
Quote:
Originally Posted by xtenglong View Post
 

Are the drivers prone to rattling for deep bass, or is it mainly for the MK3 now that they cut out a grid on the driver allowing more air to move? I've had an issue with my left cup rattling and a bit on my right when the volume is turned up. I just exchanged it but the problem is still there. I just tried loosening the screws and tightening the screws holding the driver together. It helped a little bit, but the problem is still there. I'm using an O2/ODAC, no gain, and the rattling starts before I'm in the 12 o'clock position. Would Newplast around the drivers to hold down any direct vibrations help?

 

I've replaced diaphragms for several people whose headphones rattled. In each case, the diaphragms were warped making a sort of hump which moves the diaphragm closer to the magnets on one side. I think the rattle is caused by the hump vibrating against the magnets when there is a lot of bass producing greater diaphragm excursion.

 

I don't think adding Newplast or similar material will have any effect but there's only way one to find out.

 

Loosening and retightening the screws holding the two driver frames together won't accomplish anything. There are 2 snap tabs on either side of the driver frames that prevent fatigue and loosening of the driver frame screws/threads. The two sets of neodymium magnets, one set on either side of the diaphragm, repel one another. Think of the driver screws and snap tabs as redundant systems that keep the two driver frames from flying apart.

post #2258 of 2259

The rattling on the left side stopped now after playing with the screws. There still is rattling on the right side. I'll see if I can get rid of it by playing with the screws more. I think the tensions on the screws weren't evenly distributed, so I'll try tightening them in a star pattern.

 

I'm having a tough time believing that two headphones in a row would have the same defect, on both ear cups every now and then. There are a number of people in the MK3 thread that had the same issue but it went away after modding. My hypothesis is that since one of the grid has been cut open, more air is flowing through so the diaphragm is moving more. The rattle isn't that bad, I just notice it on songs like Gesaffelstein - Destinations. I've been testing the headphones with a bass shaker test now.

 

EDIT: Just got home, played around with the screws again. Can't seem to fix the rattle on the right side, so I guess I'll try to exchange it again.


Edited by xtenglong - 12/4/16 at 8:09pm
post #2259 of 2259
Quote:
Originally Posted by bluemonkeyflyer View Post
 

I've replaced diaphragms for several people whose headphones rattled. In each case, the diaphragms were warped making a sort of hump which moves the diaphragm closer to the magnets on one side. I think the rattle is caused by the hump vibrating against the magnets when there is a lot of bass producing greater diaphragm excursion.

 

I don't think adding Newplast or similar material will have any effect but there's only way one to find out.

 

Loosening and retightening the screws holding the two driver frames together won't accomplish anything. There are 2 snap tabs on either side of the driver frames that prevent fatigue and loosening of the driver frame screws/threads. The two sets of neodymium magnets, one set on either side of the diaphragm, repel one another. Think of the driver screws and snap tabs as redundant systems that keep the two driver frames from flying apart.

 

Dang you nail it! I got the *exact* same problem on a YH100 driver: http://www.head-fi.org/t/824322/

 

It plays everything nicely but loud deep bass makes the driver give physical BZZZ BZZZZZZZ noises as if it were touching something it's not supposed to. 

 

Guess I'm SOL? :devil_face: 

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