Fostex T50RP Incremental Mods and Measurements
Jul 18, 2012 at 11:54 AM Post #31 of 2,832
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In one of the threads, Dan of Mad Dog indicated that there might have been an apparent driver modification on the end of Fostex.  He indicated, he was getting better measurements on his headphone offering with the Shure pads over the HM5 pads.


Thanks for the info. Did he mention these apparent driver changes occuring in which approximate generation of T50RP's (the month and year he had purchased these)? If this is true, I'd like to know if this is the same variant BMF has measured in these FR graphs, and if I have these as well.
 
Jul 18, 2012 at 12:58 PM Post #32 of 2,832
Quote:
Thanks for the info. Did he mention these apparent driver changes occuring in which approximate generation of T50RP's (the month and year he had purchased these)? If this is true, I'd like to know if this is the same variant BMF has measured in these FR graphs, and if I have these as well.

 
I don't recall fully.  However, it also appears around this time, the gold rods that are connected to the ear cups also changed slightly.  Before, they were a bit more textured and had a slightly rougher finish.  The newer ones seem to be a bit smoother.  I remember a picture was posted in one of the threads of the two side-by-side and you could see the variation in the color of the rods, too.
 
Jul 18, 2012 at 1:34 PM Post #33 of 2,832

Thanks for the info. Did he mention these apparent driver changes occuring in which approximate generation of T50RP's (the month and year he had purchased these)? If this is true, I'd like to know if this is the same variant BMF has measured in these FR graphs, and if I have these as well.

I forgot to include this information. I just updated the thread.
 
All mods and measurements were made using a current production, recently shipped  set of T50RP's with the new color/texture metal hangers and the new non-textured, translucent white driver dampener.
 
Jul 18, 2012 at 4:26 PM Post #34 of 2,832
Nice job, BMF. Thanks for all of your hard work! Any chance you could post some measurements of other headphones or well-known T50RP mods (Paradox, Mad Dog, etc. if you can get your hands on them)? Since we can't really compare measurements between different measuring rigs and systems, that would be extremely valuable.
 
Jul 18, 2012 at 5:03 PM Post #35 of 2,832
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Nice job, BMF. Thanks for all of your hard work! Any chance you could post some measurements of other headphones or well-known T50RP mods (Paradox, Mad Dog, etc. if you can get your hands on them)? Since we can't really compare measurements between different measuring rigs and systems, that would be extremely valuable.

I don't have Paradox or Mad Dogs. I would be pleased to measure and include the data if anyone is willing to loan their TP1, Mad Dog, and Paradox to me.  I'll pay shipping both ways.
 
I'll add my measurements of my LCD2 v.1 to the database. I used the same exact measurement chain and methodology that I used for the incremental measurements. You can then compare my LCD2 measurement vs Tyll's/purrin's LCD2 v.1 measurement, do the math to calculate an "offset," and have a "pretty good" idea how my incremental mods might measure through theirs setups. 
 
This offset adjustment process is not required, though, to make use of the incremental mod database "as is."  The first measurement I posted to the database is "All Stock" which is the baseline. Compare all graphs relative to one another and against the baseline graph.
 
Jul 18, 2012 at 6:17 PM Post #36 of 2,832
That's unfortunate, I purchased the HM5 pads because of the thickness and comfort, and didn't know the Shure pads actually measured better or flatter.
 
But I guess the upside to the HM5 pads are that they introduce more soundstage, right? That's something the FR graphs can't show.
 
Jul 18, 2012 at 10:35 PM Post #38 of 2,832
I don't recall fully.  However, it also appears around this time, the gold rods that are connected to the ear cups also changed slightly.  Before, they were a bit more textured and had a slightly rougher finish.  The newer ones seem to be a bit smoother.  I remember a picture was posted in one of the threads of the two side-by-side and you could see the variation in the color of the rods, too.


Post # 6753 in the main T50RP thread shows old driver paper in a T50RP and new driver paper in a T20RP which is the same in the current generation T50RP.
 
Jul 19, 2012 at 7:15 PM Post #41 of 2,832
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Quick question: for someone who is new to T50rp modding, what is a good "jumping off point" for modding materials+pad combination? Thanks. :)

 
The "full" BMF 8.1 mod process.  Seriously.  Actually, if you go through the graphs BMF posted, you'll see benefits with pads, stuffing (e.g. Rite Aid cotton), properly adjusting the output for the bass vents as well as the bass hole size on the baffle (where the ear pads and driver are located.  If you start off with the pads, cotton and adjusting the bass vents and port,  you'll probably get the most gain.  Then, you can move into the rest of the BMF 8.1 mods with the acoustic foam, newplast, heavy felt, adhesive-backed felt and the Dynamat.
 
Jul 19, 2012 at 8:57 PM Post #42 of 2,832
Quote:
 
The "full" BMF 8.1 mod process.  Seriously.  Actually, if you go through the graphs BMF posted, you'll see benefits with pads, stuffing (e.g. Rite Aid cotton), properly adjusting the output for the bass vents as well as the bass hole size on the baffle (where the ear pads and driver are located.  If you start off with the pads, cotton and adjusting the bass vents and port,  you'll probably get the most gain.  Then, you can move into the rest of the BMF 8.1 mods with the acoustic foam, newplast, heavy felt, adhesive-backed felt and the Dynamat.

The simple mods are pretty self explanatory and I think I can do with stuff I have laying around.... But do you know how much the acoustic foam, newplast, heavy felt, adhesive-backed felt, and the Dynamat is going to cost? Just trying to get an estimate of a total cost here.
 
Jul 19, 2012 at 9:09 PM Post #43 of 2,832
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Can't wait for the Paxmate log pictures.
 
Can I ask what pads you used for your Gold Standard measurements? Have you tried measuring these with HM5/003 pads?

 
I measured my BMF DBV mod with Stock T50RP pads and FA-003 pads. I generated SPL graphs, Waterfalls, and Spectrograms for each. I also generated Spectrograms for my LCD2 and the Anonymous headphones. I photographed the Paxmate Logs over Acoustipack Lite and the Cotton + Fiberglass overlay. I uploaded everything to the database (Post # 1 in this thread). Since I did not incrementally measure with and without the Paxmate Logs, I make no claims about their contribution, if any, to the SQ variance which is very, very good.
 
Previously, I have tried a 2-layer cross-hatch of Paxmate strips over Acoustipack Lite. I also tried 3x70 mm Paxmate Logs in 3 columns parallel with the Acoustipack Lite, both with varying results. Bottom Line: You have to try different materials and configurations to find out what works for you.
 

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