Just listened to some Fostex T50RPs today... WOW!

[mrspeakers]

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So here's a question for all you guys.
 
- Acoustic foam lining the inside of the cups
- Plasticine filled in the baffles, and lots of it (not overdamping)
- Black Creatology felt glued in place of the stock white foam, 1 single layer
- Bass port felt untouched but port is closed about 2/3rds of the way (maybe a bit more) with electrical tape on the outside of the cup
- Stock black felt on the ear side of the baffle has been removed
- Dynamat on the ear side of the baffle
- Two layers of acoustic foam doughnuts over the Dynamat on the ear side of the baffle
- Shure 840 pads with center foam cut out of them
- Leather belt AKG K701-style headband
 
 

I have a much simpler suggestion.  
 
Remove the craft felt, put about 6 or 7 "regular" cotton balls (tease them apart to loosen the fibers) into the cup, and apply a reflex dot to the center square only on the inside of the driver.
 
With all due respect to transport and micropore, that's a short-term adhesive product meant to last for a couple of days.  It's unknown how this will age, or if the glue will even stay tacky and hold for extended periods, or how the aging of the adhesive may change the sound.  For the center reflex dot, I used electrical tape, which should adhere for years and won't change properties.  
 
You'll need to fiddle with the porting a bit, but on my 840 setup about 80% open yielded a very nice sound with extended bass, and clear highs.  You could also cover a second or third square with the electrical tape as an experiment.  It should brighten things a little further.  
 

 

[hans030390]

When adding cotton balls to the cups, is it better to place them around the center post or on top of that as well? I haven't had much time to experiment with them.

 

[hans030390]

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You'll need to fiddle with the porting a bit, but on my 840 setup...

What exactly is your 840 setup, as far as there being/not being anything on the front side driver baffle/under the earpads?

 

[mrspeakers]

The cotton balls are essentially fluffed up and fill the whole ear cup uniformly.  
 
This is the exact configuration for Rastapants 2 840 Pad Edition (so far, but I am getting a few requests to post what I have).  Further changes should be reversible from these if I do anything else...
 

1. Plasticine inside surrounding the driver
2. Some Akasa on the larger areas of clay (make sure to not overdo it or the cup won't close)
3. Akasa on the entire back cup.  Fatmat between the Akasa and cup is optional.  (I like the idea of the paintable dampening goo, never heard of it before but may give it a test)
4. Some Akasa around the driver on the ear side out to the edge of the cup
5. Felt over ear-side driver removed
6. 6-7 cotton balls teased apart and spread evenly inside the cup
7. Vent 80% closed
8. No felt on the inside of the driver
9. Reflex dot of electrical tape in the center square (could try more tape, I wouldn't do over 33% though).  I know this would boost highs, but I'm not sure how much it will reduce bass.
10. Hard 5mm risers under the back of the 840 pad (anything will do, and can do a bit more than 5, too)

 
This is not a "bright" headphone but the frequency response is OK and the transients are excellent.  The spectral sound is more like the JH16, with a rise in bass below 200Hz and an extended but a little down in the highs.  I'm still tuning this and will update when I get the reflex balanced with the port a bit better.  Personally, I'd like to reduce the bass a bit to make this more neutral....  A key thing is that I have successfully eliminated a resonance that existed at 1K and a big dip at 4-5K.
 
Regarding brightness I can't say how this will stack against what you have for sure, but it should be cleaner and the frequency response is pretty good (and will likely improve this weekend if I have play-time).  It's not bright, but the treble is extended and very detailed, just not real "forward."
 
I make no claim this is better than a BMF because I haven't heard or measured one, but it has the benefit of using materials that are more likely, I believe, to last.  Further, my experiments with both Transpore and Micropore left me very unsatisfied with them (didn't again try a BMF). With my test gear I can show these are WAY better than stock in every dimension with no glaring hole except the 4-5 dB rise in low bass (this gives a big, solid sound without impacting the mids with bloom).
 
You can see here how fast and clean the performance is from 2K up.  As Purrin can validate, that's spectacularly clean and fast.  I'm not filtering or smoothing this, either.  In 0.4ms the output above 2KHz is at least -40dB down.  Once I get that spectral tilt smoothed out to bring the bass down these are going to sound really good.  I think Purrin would validate that over 2K this is spectacularly clean (if he notes this post) 
 
Again, thanks to Purrin for inspiring me to get off my butt and do a little real engineering.
 

 
 
 
 
 

 

[micmacmo]

mrspeakers, have you tried any fill material besides cotton? I couldn't find any cotton balls around home, but I did find some 100% polyester fill (go figure). So far, I like what I'm hearing. It adds some brightness/energy that was missing from the sound. It's an improvement over the melamine foam I was using. Even a thin 4mm slice of the foam seemed to drain life from the music, although I found it was an improvement over just the paxmate & plasticine.
 
I wonder if wool batting will work better. Any insight?
 
 

 

[200poundsofamp]

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So, if someone has another idea that will retail all the lush natural sound I get, but can tone the bass down slightly, and boost treble ever so slightly, I'd be open to ideas.
 

To me a small 3/8" round plastic furniture pad stuck on the center square behind the driver is perfect. You can use something larger than that if you want more brightness, but it makes the transition from midrange to treble peakier.
 
You can add felt or other material over the back of the driver to damp them harder and brighten the entire sound signature a bit. Too much and you kill the bass extension and sound stage though. You could also try differential dampening.
 
You can more specifically tune the bass by closing off the vent with electrical tape, why that works I don't know, but it seems to.
 
Quote:

mrspeakers, have you tried any fill material besides cotton? I couldn't find any cotton balls around home, but I did find some 100% polyester fill (go figure). So far, I like what I'm hearing. It adds some brightness/energy that was missing from the sound. It's an improvement over the melamine foam I was using. Even a thin 4mm slice of the foam seemed to drain life from the music, although I found it was an improvement over just the paxmate & plasticine.
 
I wonder if wool batting will work better. Any insight?
 
 

 
I've been using a circle of cut down egg crate foam, seems to add some brightness too, and not in a bad way at all. Fostex does that stock on the T20v2, seems to work here too.
 
I'm going to test foam vs cotton vs nothing and see what happens.

 

[Armaegis]

You guys ever try using cork? About $2/sq.ft. at an office supply store.

 

[dogears]

The Pawbulous Silver Pawstex is singing with the Dared MP5! It added a warmth to the sound that made it sound more natural specially on vocals. Recommended for a cheap setup. I'm running Musiland02US>DaredMP5>FostexT40

 

[Arleus]

Hi guys, I can finally join this club - my T50rps arrived a week ago, and I've been tinkering with them since.
 
I was going to post here and ask if anyone else had a resonance problem around 1kHz, but I see you've already addressed this mrspeakers - do you know which part of your mods was responsible for taming this? I figured that it was probably a structural resonance, rather than an aerodynamic one (a quick calculation tells you that an acoustic 1/4 lambda standing wave at 1kHz would have to be in a space of about 8cm in length and match a one open one closed boundary condition - I don't think this can happen on this scale in the T50rp), so I added a bit more plasticine to the inner baffle, and I think it helped a little, but certainly didn't solve the problem entirely. 
 
As for cotton wool vs polyester, I first tried some polyester soft-toy filling (it's kind of fluffy, looks a bit like cotton wool, but coarser, more wiry, and stiffer), but found cotton wool to be far superior in the end. I reckon our cotton ball sizes are different in the UK to yours, mrspeakers et al, as I've got a little under one full ball in each cup. I could probably just about cram 2 in each cup at most, but when I tried, it killed the bass off entirely. 
 
Currently my mods are: plasticine and paxmate on the back and sides of the inside cups; default black felt over the vent (no electrical tape); RP2 levels of plasticine on the inner baffle, plus a little extra around the sides of the driver; about 3/4 of a cotton wool ball (whatever Wilko's default size is) in each cup; paxmate on the ear-side of the baffle, with a hole cut for the driver diamond and the equalisation vent; stock pads. I've not touched the stock felt/cloth on either side of the driver, nor have I tried a reflex dot yet. 
 
It's not bad, but still needs some work, especially around 1k. I have to say though, the improvement from stock is already immense. The T50rps are rather more expensive in the UK than the US, and had I bought it with no intention to mod it, I would have been disappointed with the sound I got for the price - the balance has tipped a long way in the other direction now, and these are starting to approach my 702s in terms of quality. In fact, I think the mids are better, but I'm missing a touch of high end sparkle, and the bass doesn't dig quite as deep. I know the 701 series doesn't have a reputation for its bass, but it really does extend very low when called upon to. Oh, and the 702s have a huge lead on soundstage, but you can't have it all! So, any suggestions would be much appreciated.
 
Oh, incidentally, I've been playing around with the idea of getting some custom cups 3D printed. I think the polymer the printing process uses is quite light in general, so it will need generous mass damping, but in any case, I'll definitely let you guys know if I ever do get around to doing that!

 

[mrspeakers]

I found a bit more cotton killed the 1k resonance  completely.  It is absent from my waterfalls....  Listening to LFF's Paradox I would recommend people leave the white felt on, but I haven't even started to try to mod these without the 003 pads.
 
Haven't tried wool but would be surprised if it is better than cotton.  Cotton is better than poly.

 

[rawrster]

Does anyone here use tube amps with the T50RP? I was wondering if they found good results with them as I'm looking at buying a tube amp to have a mix of ss and tubes as well as make use of my other dac finally.
 
I don't want anything too expensive or large but looking at amps like WA6, something from MAD, maybe a DNA Sonnett but wondering if any amp at around those prices does well with these.

 

[micmacmo]

Arleus, I totally agree with your comparison to the k701 wrt sparkle, space and bass. I really enjoy the k701 and I'll be keeping them regardless. But I find that when I first put them on my head, I always feel there's something thin about the sound. It takes a few moments for my ears to retune to them. Not so with the t50rp.
 
Armaegis, where would you put the cork and what role would it play? Replace the paxmate?
 
I'll pick up some cotton balls and, if I get to a fabric or quilting store, some wool batting too. I'm concerned about the polyester fill. I hear occasional crackling when I put the phones on and I think it might be static generated within the polyester. That can't be healthy.

 

[Armaegis]

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Armaegis, where would you put the cork and what role would it play? Replace the paxmate?
 
 

 
Sort of a middle ground absorber and soft reflector. I've seen it used in a couple mods on the forums before. I would think in the cups would be best, but it's hard to work cork without a flat surface... maybe the baffle front?
 
The other thought was that it would be somewhat easier to use a dremel to cut cork into the wedge patterns like seen in acoustic foam panels, but once again within the confines of a small cup and weird surfaces it might not be feasible?
 

 

[punkaroo]

I plan on picking up a T50RP soon. I'll post impressions of it with my DNA Sonett
Quote:

Does anyone here use tube amps with the T50RP? I was wondering if they found good results with them as I'm looking at buying a tube amp to have a mix of ss and tubes as well as make use of my other dac finally.
 
I don't want anything too expensive or large but looking at amps like WA6, something from MAD, maybe a DNA Sonnett but wondering if any amp at around those prices does well with these.

 

 

[snakeeater69]

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I plan on picking up a T50RP soon. I'll post impressions of it with my DNA Sonett


 

Good luck with that. For some these sellout  fast. Well, at least the $74 ones does.