Fostex T50RP Incremental Mods and Measurements
May 2, 2013 at 4:50 PM Post #496 of 2,832
Did you do a modified bass port on the outside? Or did you leave the outside vents alone?
 
May 2, 2013 at 6:59 PM Post #497 of 2,832
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I okay I finally got T50rp enough to my liking. Bass is good but could be better and could extend lower. Mine can not go lower than 27hz. Feel free to make any suggestion. Here's my tweaked BMFv3 so far:
 
1. Stiff craft with double sided type over stock white felt and driver
2. Plasticine Flush Mass Loaded in the baffle compartments (I did not weigh it) and also seal around the circumference
3. Silverstone foam both side of cups with rips, felt top and button of vents with black felt.
4. A piece gauge over foam and felt followed by a piece of 7mm Rock Wool with a hole directly where the vents with black felt is followed by 3 thin sheets of rolled rite aid cotton.
5. Scotch taped bass port with a small needle hole on ear side.
6. HM5 with inner tube for pads.

 
Sounds like you're making progress. 
 
Same question jasonb asked: Are the cup vents in their stock form with internal black felt in place? If so, don't make a modified bass port or you will get less bass than you have, now.
 
If you have Shure 840 pads, try them with your current configuration to see if you hear more bass.
 
"3 thin sheets of rolled rite aid cotton" - If you separated the cotton into the single layers, 3 layers may have minimal effect but take it out to see if you hear any more bass.
 
Stiff felt - You could try removing it which will give you more bass. If that makes the bass too boomy, you could try punching 3mm holes in the stiff felt over the 4 corner driver grids.
 
Rock Wool: Reducing the thickness will give you more bass and less treble. You could try 5mm thickness and 5x5 cm (width x length).
 
Looking at the Pad Rolling measurements, stretching the pads onto the cups will probably reduce bass and increase treble; taping the pads onto the baffles/cups should increase bass and decrease treble. I have not modded and tuned using HM5 pads.
 
If you want to increase bass even more, remove the black felt covering the inside of the cup vents (save it in case you want to go back to stock). Doing so May make the bass boomy and require a modified bass port to bring it back under control.
 
The only way to determine which tweak and tweak combination creates any given effect is to do them one-by-one, systematically, and take notes about what you hear.
 
Good luck.
 
May 2, 2013 at 10:01 PM Post #498 of 2,832
Oops, I meant the baffle port. The little hole of the ear pad side near the top screw. I left the vents alone outside and inside.
 
On a side note does your modded t50rp increase/enhance echoing effect. I modded a t50rp with 840 pads a few years back and I don't recall hearing echoing effect as pronounce as my current on modded t50rp.  This only happens to certain songs with a hint of echoing.
 
 
May 2, 2013 at 10:04 PM Post #499 of 2,832
should be less ringing after modding. the internal dampening is supposed to reduce the ringing. 
Quote:
Oops, I meant the baffle port. The little hole of the ear pad side near the top screw. I left the vents alone outside and inside.
 
On a side note does your modded t50rp increase/enhance echoing effect. I modded a t50rp with 840 pads a few years back and I don't recall hearing echoing effect as pronounce as my current on modded t50rp.  This only happens to certain songs with a hint of echoing.
 

 
May 2, 2013 at 10:38 PM Post #500 of 2,832
should be less ringing after modding. the internal dampening is supposed to reduce the ringing. 


I agree. After the initial build and successful tuning, there should be no echo unless that's the way the music was recorded. The SQ should be clean and clear with good extension on both ends, textured, non-boomy bass, and treble detail without sibilance.
 
May 3, 2013 at 7:39 AM Post #501 of 2,832
Has anyone tried keeping the treble reflector and just removing the felt completely from the back of the driver? I couldn't tell if this mod was only successful with the felt  or not.
 
May 3, 2013 at 11:39 AM Post #502 of 2,832
Speakng of felt. What is the stiffened craft felt behind the driver supposed to do exactly. I just grabbed a sheet from Hobby Lobby for 85 cents so ill try it, but was just curious what it is supposed to do.
 
May 3, 2013 at 11:55 AM Post #503 of 2,832
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Speakng of felt. What is the stiffened craft felt behind the driver supposed to do exactly. I just grabbed a sheet from Hobby Lobby for 85 cents so ill try it, but was just curious what it is supposed to do.

From what I understand, it's supposed to tame the bass and help out the highs. I honestly just did all the mods at once so I have no idea what each one does on it's own haha. Figured go big and edit later.
 
May 3, 2013 at 1:28 PM Post #504 of 2,832
I attached a layer of the stiffened felt to the back of the driver with double sided tape along the edges. I also removed the fabric in front of the driver, between the ear and the driver. I was expecting the stiff felt to murder the bass, but if anything it has made it tighter sounding, but it doesn't seem to have brought the bass level down any. I also think it brought the treble up a smidge too. I don't feel the urge to add the +2db of treble I have been adding with my E17's EQ. For 85 cents and 15 minutes of my time, I guess it wasn't a waste.  
 
Next, we will see what the Alpha pads do to them. I'm expecting a huge difference in soundstage and imaging, but I'm not sure what to expect in terms of frequency response. 
 
May 3, 2013 at 2:09 PM Post #505 of 2,832
should be less ringing after modding. the internal dampening is supposed to reduce the ringing. 


I agree. After the initial build and successful tuning, there should be no echo unless that's the way the music was recorded. The SQ should be clean and clear with good extension on both ends, textured, non-boomy bass, and treble detail without sibilance.


It's either all of this or the song really have echoes in it, only just now that your headphones are resolving enough to make it out. :p
 
May 3, 2013 at 2:33 PM Post #506 of 2,832
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Next, we will see what the Alpha pads do to them. I'm expecting a huge difference in soundstage and imaging, but I'm not sure what to expect in terms of frequency response. 

The bottom of the first post has some frequency response graphs with different pads including the Alpha Pads. Pretty jagged highs.
 
May 3, 2013 at 2:57 PM Post #507 of 2,832
Those graphs were also taken on a T20rp, not a T50rp. i will find out what they do either tomorrow or monday when they arrive.
Quote:
The bottom of the first post has some frequency response graphs with different pads including the Alpha Pads. Pretty jagged highs.

 
May 3, 2013 at 3:00 PM Post #508 of 2,832
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Those graphs were also taken on a T20rp, not a T50rp. i will find out what they do either tomorrow or monday when they arrive.

Right, but they use the same drivers I think. Otherwise that whole section of the post would be negligible. Do you have a DIY frequency response setup? I really need to make one...
 
May 3, 2013 at 3:08 PM Post #509 of 2,832
I probably could set one up. I have a Behringer measurement mic that I used to use for tuning my home theater system. I'm not sure if it would work with my current laptop though. 
 
Anyway, people on the Mad Dog thread speak highly of the Alpha pads. Most, if not all, seem to think they are better than the 840 pads. 
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Right, but they use the same drivers I think. Otherwise that whole section of the post would be negligible. Do you have a DIY frequency response setup? I really need to make one...

 
May 3, 2013 at 3:51 PM Post #510 of 2,832
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I probably could set one up. I have a Behringer measurement mic that I used to use for tuning my home theater system. I'm not sure if it would work with my current laptop though. 
 
Anyway, people on the Mad Dog thread speak highly of the Alpha pads. Most, if not all, seem to think they are better than the 840 pads. 

Yeah, I've seen a lot of positive reviews about them (isolation, soundstage, and imaging). I'm definitely interested in getting some, I'm not too concerned with the FR on the high end anyway, it's not like there's ever been a headphone that ISN'T sawtoothed up top. You should definitely comment on your findings with the pads
smily_headphones1.gif

 

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