Fostex T50RP Incremental Mods and Measurements
Nov 26, 2012 at 8:39 PM Post #227 of 2,831
Today, I received a pristine set of Amfiton TDS-7 vintage Russian headphones from my very good friend, Dmitry. The SQ and FR from them is very similar to the SQ/FR from my modded Fostex T50RP/DBV #3. Both have well extended bass and treble response. TDS-7 mids are a little bit more recessed but still clear and lush. My DBV #3 bass is less pronounced than the TDS-7 which is tilted more towards the bass register. TDS-7 treble is slightly less clear than my DBV #3 but both are detailed and free of sibilance/fatigue. TDS-15's bass is less than the others but well extended with a general tilt towards the treble range. TDS-5M generally "splits the difference" between bass and treble after modding; I have not modded TDS-15 and TDS-7, and don't plan to do so. Fostex T10's are wonderful after modding, as are T20v2.
 
Please excuse the poor quality of these iPhone photographs.
 
 

 
Left to Right: TDS-16 (Kiev), TDS-15, TDS-7, T50RP/DBV #3
 
 
 
 
 
 

 
Left to Right: Amfiton TDS-7, T50RP/DBV #3, Fostex T10, Amfiton TDS-5M
 
Nov 27, 2012 at 9:17 PM Post #230 of 2,831
Quote:
pardon my ignorance, but this has been gnawing at me a bit.. What does DBV stand for?

 
DBV just happens to be a labeling system that Blue Monkey Flyer has established to keep track of the various modification levels of his headphones.  Currently, the DBV is at # 3.  However, Blue Monkey Flyer has also posted some tips within one of the T50 threads so that a person performing the mods, can make some small adjustments to that version to vary the sound slightly.
 
Don't worry, DBV isn't some super top-secret for a code name of the Fostex mod that we can't get our hands on.  It has been thoroughly documented by Blue Monkey Flyer in the posts he's applied here in the forum.
 
Enjoy!
 
Nov 27, 2012 at 9:34 PM Post #231 of 2,831
I know that.. I was just curious how it came to be "DBV", LOL.  I am currently listening to BMF's DBV #3 
beyersmile.png

 
Nov 28, 2012 at 12:54 AM Post #233 of 2,831
Nice pictures there BMF! Favourite ( minus the T50) one being? Be careful with the T-10 badges they tend to fall off at inopportune moments. I attached mine with some contact cement on both bits.

These even have the original plastic protection on them I thought they were bubbling but it was that factory plastic coating !
 
Nov 28, 2012 at 9:01 AM Post #234 of 2,831
Quote:
Nice pictures there BMF! Favourite ( minus the T50) one being? Be careful with the T-10 badges they tend to fall off at inopportune moments. I attached mine with some contact cement on both bits.
These even have the original plastic protection on them I thought they were bubbling but it was that factory plastic coating !

 
Thanks, nick n. My favorite in terms of the sound is my modded T50RP - DBV #3. This is not surprising since I tuned it for my preferences and audio chain. Of the others, I like them all:
 
TDS-7: The best in stock form out of the entire group. They sound wonderful though tilted towards the bass side. Still, very clear/lush mids and plenty of treble without fatigue. Excellent sound stage and imaging. Very enjoyable except clamping pressure. 
 
TDS-15: All stock. Tighter bass and less quantity than TDS-7. TDS-15 is titled towards the treble end. Very good mids like the TDS-7. Coolest looking vintage Russian headphones.
 
TDS-5M: Modded following DBV #3 configuration with cotton, fiberglass, and treble reflector: Bass and treble somewhere between TDS-7 and TDS-15. Very good mids.
 
TDS-16 (Kiev): I have not been able to listen to it because I must make a 5-pin xlr din to TRS adapter.
 
Fostex T10: I added DBV #3 cotton, fiberglass, treble reflector to the stock yellow biscuit. Similar but all around better sound than TDS-5M in its present modded state. One of the badges detached during shipping. I was fortunate to notice before I discarded the box. I secured both with a thin ring of super glue. Beautiful "polished" look, cushioned headband, and better build quality than current production T50RP/T40RP/T20RP Mk2.
 
Not shown: 
 
Fostex T20 v2 (2 sets): Modded with a ring of Newplast around the driver, felt disk the same size as the driver,  treble reflector under the felt, some cotton between the driver felt overlay and the stock foam puck. They sound similar to my modded T50RPs.
 
Pioneer SE-700, SE-500, and SE-L401: Some of the most beautiful headphones ever made, especially SE-700. Too bad they don't sound half as good as they look. Bass is weak from the SE-700 and non-existent in the others. I'm looking for a NOS Pioneer junction box.
 
LCD2 v1: I love the sound and the look. Excellent SQ, sound stage, and comfort.
 
Audio Technica 705 (NOS): Beautiful look and build. I have not listened to them, yet, because I need to wire up the "box" to my speaker taps.
 
Thunderpants TP1 "Double Dragons": Beautiful engraved dragons and wood cups. Sound, not so much.
 
Nov 28, 2012 at 9:13 AM Post #235 of 2,831
Quote:
 
DBV just happens to be a labeling system that Blue Monkey Flyer has established to keep track of the various modification levels of his headphones.  Currently, the DBV is at # 3.  However, Blue Monkey Flyer has also posted some tips within one of the T50 threads so that a person performing the mods, can make some small adjustments to that version to vary the sound slightly.
 
Don't worry, DBV isn't some super top-secret for a code name of the Fostex mod that we can't get our hands on.  It has been thoroughly documented by Blue Monkey Flyer in the posts he's applied here in the forum.
 
Enjoy!

 
Exactly as wje described. 
 
Last year I used my Dremel cutting tool to open the faux vents at the top of the cups. I hypothesized that doing so would enhance the bass and provide a more open sound. I dubbed this set "Double Bass Vents" (DBV). All manner of mods failed to support my hypotheses. The bass was completely out of control, loose, boomy, and bloated. The bass over-whelmed the mids making them sound veiled and muffled, and squashed all remnants of treble. 
 
I sealed the opened faux (top only) cup vents in that set of DBV's which I used later when developing DBV #1, #2, and #3. I used "DBV" as a means of distinguishing that particular mod configuration from other modded sets in various stages of experimentation. I have continued to use "DBV" simply for consistency/continuity when describing this configuration and variations despite its misnomer - the DBV (#1, #2, and #3) series does not have double bass vents.
 
Nov 28, 2012 at 1:43 PM Post #236 of 2,831
Did you try half the vents on bottom and half the vents on top? So the same number overall, but more evenly distributed.
 
Nov 28, 2012 at 3:30 PM Post #237 of 2,831
Did you try half the vents on bottom and half the vents on top? So the same number overall, but more evenly distributed.


No. Good idea. I would try it if I still had that set with open top vents but it is gone. Have you tried this?
 
Nov 28, 2012 at 4:24 PM Post #238 of 2,831
No... my set have been inadvertently glued shut by the rubber I sprayed inside the cup 
rolleyes.gif
 (on the plus side, this prevents further tampering which means I'll actually sit and listen to music rather than mess with things further)
 
For what it's worth, I do think the seal and dampening from coating the insides does make a difference. It's a real pain in the tush to apply though, quite irreversible, so it would make a good "final step" once you've decided on what the rest of your mods will be (since the rubber goes on before anything else). 
 
Nov 29, 2012 at 3:17 AM Post #239 of 2,831
No... my set have been inadvertently glued shut by the rubber I sprayed inside the cup 
rolleyes.gif
 (on the plus side, this prevents further tampering which means I'll actually sit and listen to music rather than mess with things further)
 
For what it's worth, I do think the seal and dampening from coating the insides does make a difference. It's a real pain in the tush to apply though, quite irreversible, so it would make a good "final step" once you've decided on what the rest of your mods will be (since the rubber goes on before anything else). 

 
I think when I get ahold of some proper cotton I'll have to glue mine shut so I stop modding and start using them more too!
 
Dec 5, 2012 at 3:56 AM Post #240 of 2,831
Quote:
REW Generated Sweep > Calibrated MacBook Pro Soundcard  > Glass Toslink > Dacmini with 1 Ohm Output Impedance Mod > Headphones > Calibrated Panasonic WM-61A Microphone > Calibrated Phantom Power Supply > MacBook Pro > REW Analysis

 
 
Panasonic WM-61A Microphone, Did you mod them for 3wire or you used the 2wire method ?
 


 
How did you calibrate the Microphone and Phantom powersupply ?
 

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