So my friend borked the cable on his Urbanears Plattan and asked me to fix them. This necessitated recabling the entire thing, and I figured while I was in there I could have some fun.
I didn't take too many pics of the Plattan while I was in there, but enough to get the gist. They are surprisingly easy to disassemble. The cup assembly isn't actually a cup. There's a ring which the headband is connected to, a rear plate, and the driver assembly which screws into the rear plate. So basically pop the pads off, take out three screws, and the whole thing comes apart. Sandwiched between the rear plate and driver is a piece of thick felt.
The cup is closed except for some tiny holes/vents on the side. The rear of the driver magnet plate has no vents either. So any acoustic pressure that goes into the cups is directly from the rear driver plate vibrating, or reflections from the ear back through the baffle diffuser ring.
So anyhow, my approach to modding this was pretty standard. Vibration-damp the crap out of it and improve the seal. I didn't worry too much about acoustic damping since there really are no reflections to speak of in the design, and my aim would be to eliminate those as much as possible anyways.
fatmat (or dynamat, or any vibration damping material)
acoustic foam (I think this was Akasa, rubber backed and relatively heavy)
about half an hour
The rear plate composes of the main plate and a silver "washer" which as far as I can tell is purely for aesthetic purposes. Anyhow, this washer means you now have large mating surfaces between the ring and plate that could cause vibration or leakage. So I sprayed the washer with some liquid rubber (roofing sealer) and cleaned up the edges with some sandpaper after it dried. This was to provide better seal and minimal vibration damping. On the rear plate itself I stuck a large piece of fatmat.
One small piece of fatmat on the rear of the driver itself. Just cover it.
Replace the felt with some acoustic foam. I popped it out and traced the profile on the foam back. Be careful to figure out the orientation, because it is not symmetrical. I tried to keep the shape as close as possible, so that when I laid it sticky side into the back, it would further seal and hold everything together. The ring actually has a bit of a lip on the back edge, so you can stick the acoustic foam to that before putting on the rear plate assembly.
After reassembling the rear plate and driver, line the front edge with some plumber's putty. This is to provide better seal with the earpads.
Snap on the earpads and you're done.
Just linking to the album for now. The forum keeps crashing on me when I try to link the pictures directly...
Change in sound:
bass becomes noticeably stronger (gives my Pioneer HDJ-2000 a run for its money) and remains quite flat
treble response significantly improved, frequency response reasonably smooth until the upper treble where you get one strong valley/peak
detail and instrument separation are improved, in part due to better treble presence, in part due to improved decay times
Edited by Armaegis - 4/30/12 at 4:49pm