It actually sounds very good! Before dampening, there was waaay too much bass, and the upper mids had a harsh peak that made them almost unlistenable.
Looking for remedies, I cut open a black ink cartridge. Some of the larger cartridges have micro-cell sponges, which is a great dampening material to use in this case. About a 1/4" thick rough circle of dampening sits flush between the rear of the driver and the outer grille. This helped out!! Tons. but there was still too much upper mid.
The headphones stayed unused for about a month. Then I read somewhere in the Fostex T50RP thread about putting foam/toilet paper behind the earpads to change the distance between the driver and the ear.
I cut up part of a memory foam pillow, and used a couple bits behind the white ear circle pads. IT WORKED!!! Sound is more neutral than before. The bass is definitely present, mids are pretty close to being natural sounding, and highs are slightly recessed, but HF detail is still noticeable.
Compared to my modded T50rp's, the mids are more present in the SFIphones, but the T50 is still more natural sounding.
On the blu-tak vs epoxy mounting, I do believe the blutak was absorbing some resonances that I don't remember with my current revision of these headphones.
Any suggestions where to add blu tak for more dampening?
