Last 3-4 pages are somewhat hard to understand and to get the proper picture.. I believe we would all benefit from being more systematic and joining thoughts and efforts. I don't have the T50 yet and haven't done real mods, so I'm really not on par with most of you, yet I can try to think up something. We should write not only the our modding, but also the reasons behind them, I think.
I'll try to write some of my thoughts:
There now seem to be the two prevalent mods: Rastapants 2i (they're described at page 285, I believe) and BMF 6v(2/3). They are more similar than different, but there is a difference in approach to damping the driver itself. What they do both is what I'd call the preparation. Damping the driver is what I'd call tuning.
I have one point of view on preparation. IMHO, the result of preparation would be an "correct" sound - with minimum of reflections, distortion, re-emitted sound, etc. Clean, fast, detailed, etc. Tonal balance could be skewed, but tonal balance is a result, not a cause. Then, tuning should result in an even tonal balance.
What would that preparation be? Mass loading cups with dynamat, mass loading baffles with plasticine/putty AND also loading baffles on the earside as well. Covering all that with paxmate - both the cup and baffle from both sides. Also covering inner side of earpads so there would be even less reflection. IMHO, that is why velour earpads are said to have better soundstage - they don't reflect. Some people said that such a configuration sounds bland, but IMHO it's a result of skewed tonal balance and should be corrected later with tuning.
Note: in optics, there is reflection when light passes boundary between substances with different refractive indices. The less the difference, the less reflection. It applies to sound as well. To minimise reflection, one should use a several-layer system to deflect and absorb the sound waves. Something very diffuse and light near driver, then something denser, and so on and so on. The organic dried sponges seem to be a good choice for the near-driver layer. Then, teased cotton balls. Then, paxmate, then, dynamat and then the cups. There also may be a denser layer of cotton between paxmate and dynamat, depends on the density. Making cotton ball stuffing with different density across its thickness is also a good idea - more teased near driver, denser near paxmate.
The second stage of preparation would be elimination of uncontrolled variables. RP2 do some of that elimination by lining rim of the baffle with plasticine. Other uncontrolled variables are leaks from under earpads and leaks between head and earpad. First kind of leak is not hard to address - stock-like glued-on pads should be properly glued on, and with flapped pads, one might put something viscous under the flaps, but I don't think it is necessary. On the second kind of leak, leather earpads have little leak, and gel earpads have even less leak - the more isolation, the less leak. Sub-bass requires proper seal.
Now, there comes tuning. I see three things to tune: driver damping on front and rear, ports on cup, and ports on baffle. Again, tuning should first result in "proper", fast and detailed sound, and then it should be tuned further to get proper tonal balance. Bad thing, without measurements, we can't be sure what really each measure does. Seems that closing cup ports results in damping resonances and perhaps shifting them lower. However, it comes at expense of compressing bass frequencies, as air has nowhere to move.
Baffle ports seem to be overlooked. They also play role in bass, and subbass, as they leak air between front and rear. Covering them overdamps the driver and reduces bass, while having them open results in roll-off at subbass, albeit having more of the other bass frequencies. I think, they should be controlled - not by opening or closing them completely, but by changing their resistance - covering them, for example, with felt which passes air through but restricts the flow somewhat.
Now, the driver damping itself.. it is the most questionable area, and I don't have expertise with it. I only have some thoughts on reflex dots and bass rings. Reflex dots shouldn't really reflect a lot of sound when placed right on the driver, but they surely add damping that way - they are solid and don't pass air. So high-excursion bass waves get damped, and they-re mainly bass, so there's less bass and hence, more treble - as everything is relative. Still, I don't think anythink rigid and reflective is good. So instead of reflex dot, I'd use a damper dot, if there would be any need to boost treble.
Bass rings, I think, should be the last thing to implement, exactly to tune the tonal balance. I would implement one on the front, to further reduce phase shift in highs - it may reduce percieved amount of highs, but make responce more extended due to less parasitic sounds. And of course it should indeed boost the bass (relatively).
Thanks you you read it all. Maybe my thoughts would be at least somewhat useful for all of you.
![[:enrage]](http://forum-images.hardware.fr/images/perso/enrage.gif "[:enrage]")
