I think I am close to dialing these in where I want them for now. For anyone who has not been keeping up with my mods, here are my three most important previous posts on my mods (in order of most recent to least recent): 1 2 3
Since I do not have a way to measure these out, I can only judge with my imperfect ears. They might sound awful in reality, but they sound quite wonderful to my ears currently.
The bass is easily audible down to about 30Hz and has just enough weight and punch for everything I throw at it. I threw on "Derezzed" from the Tron: Legacy soundtrack and was really digging how these represented the bass in the track. Opeth's Ghost Reveries album has a very punchy, dynamic, thick sound without overdoing it. I've found it very difficult to get a proper balance with this album, and the modded T50RP seems to do it wonderfully. Very nice.
The mids seem to be properly in line with the bass. Lush, textured, and simply wonderful to listen to. Treble is nice and detailed without sounding too sibilant, bright, or artificial. Overall, these simply sound natural. The music makes the headphones disappear with ease. They are surprisingly spacious sounding with a very coherent, decent-sized soundstage and good imaging. All instruments and aspects of the music are clearly differentiated with nice separation. They seem "faster" than other headphones I've listened to. They are not always extremely 3D sounding, but headphones rarely are.
I don't want to take too much time describing them, because these are just my impressions. My impressions are likely biased and potentially no where close to reality. That said, I do believe my T50RPs in their current state offer sound quality on a level beyond any other gear I've heard. Now, that's not saying much. The nicest pair of headphones I've heard are the D2000s and HD598. I have a decent 2.1 setup as well (dedicated DIY bookshelf speakers and sub, EQed to boost known weaknesses in the bookshelf speakers) along with a nice car stereo setup (also DIY). My experience with other audio gear is relatively limited! I do like to think I have good ears, though, and I'm no stranger to music (played piano for 9 years, guitar for 4, love to sing and am at least decent at it).
I ran some sine sweeps on these (using SineGen), and I was having a hard time detecting any noticeable dips and peaks. It seems like they lightly "peak" around 100-200Hz, with a slow roll-off down to about 30-40Hz and a fairly even/flat sound up until 7-9KHz, where there appears to be a big dip. This seems almost universal with these headphones though, much like the peak at 10KHz. This is far from a perfectly accurate method of testing the frequency response of a headphone, though. But, for now, I'm very satisfied. I have no itch to go in and mess with them anymore, though I will be comparing them with the Brainwavz HM5 (FA-003 copy) once I get those in. I may adjust things after that.
Anyway, enough of all that. I don't think people are even trying this out, but here's what I've done so far:
1. Silverstone acoustic foam completely lining the cups (cut neatly, no draping, maximizing internal cup volume, cover center post)
2. Felt removed from cup vents, covered all but the bottom-most slit in Silverstone acoustic foam. Leave that bottom vent slit open (covering it with cotton, step 3, is recommended)!
3. Take 5-6 regular sized cotton balls (per cup), tease them apart completely, and place half of that in the cups evenly. Then take a thin layer of fiberloft and place that over the cotton. Repeat this. In the end, you'll have 5-6 teased cotton balls in each cup with 2 thin layers of fiberloft thrown in the mix (one in middle of cotton, one in front of cotton facing the back of the driver). It should take some light force to close the cups in the end.
4. Plasticine in the back of the driver baffle
5. Silverstone acoustic foam covering most of the plasticine
6. ~3mm wool felt on the back of the drivers (Original paper/felt removed. No reflex dots either). Cut out a square/rectangle in the middle of the wool felt (matched up with the center square on the back of the drivers, see previous post for example picture). This felt is quite a bit different than anything I've seen in the local stores.
7. Felt removed from the ear-side baffle (keep protective mesh in front of driver). Make sure the screws holding the driver in place are tight.
8. One layer of Dynamat on the ear-side baffle. Cover the open hole near the driver.
9. One layer of Silverstone acoustic foam covering the entire ear-side baffle (except for driver, outer screw holes, etc).
10. 840 earpads. No stuffing in the backs or anything like that.
11. Cover the 3 vents you closed off inside with duct tape or electrical tape on the outside of the cups. (This probably doesn't make a difference at all)
12. Take a mechanical pencil and poke the lead out a bit (paperclip would also work). Poke all along the cotton through the open vent, just enough so that the cotton does not push up against the vent so hard.
13. Use tape to tune the vent and sound to your liking. On my setup, I keep the bottom vent "open". (Updated 1/1/2012)
14. Side note: Make sure your cups/baffle are screwed on and tightened properly. I've noticed that sometimes it won't close completely if you don't pay attention.
If anyone wants to try this out, I can send them some of that 3mm wool felt I'm using for cheap (though it's super cheap on Amazon). Fiberloft is pretty easy to get, but you probably only really need just cotton in the cups.
I'm really loving how these are sounding! Hopefully someone else will try this out.
Edited by hans030390 - 1/1/12 at 2:22pm