Fostex T50RP Mods:
I followed mrspeakers' Rastapants plan with just a few changes.
1. I chose to not apply plasticine to the tiny spaces directly surrounding the drivers.
2. I did not remove the dust cover from the ear side of the drivers because in a prior mod I could not hear a difference and I like the "stock look" better.
3. I placed a clear plastic "softtouch" Bumper reflex dot over the center grid square on the back of the drivers before gluing a 1" square of felt to the back of the drivers.
4. I have not yet tried the Shure 840 ear pads.
5. I used Paxmate to seal 3.75 of 4 bass ports instead of electrical tape.
I am listening to these right now and they sound wonderful.
Plasticine in baffles for mass loading, stock white felt intact, Paxmate Plus in cup for resonance reduction. The stock black bass port felt is intact for the moment but will be peeled off soon and all but 4 mm of the top slot covered with Paxmate. You can see this dampening felt at the bottom center space directly beneath the central compartment housing the main attachment screw used for securing the headband hanger to the cups.
Here, I have sparingly brushed acetone onto the metal grid beneath the stock white felt on the back of the driver. I used an xacto knife to pull up one corner. I had to apply a bit more acetone and slowly peeled off the white felt in one piece. I saved these in case I want to go back to stock.
White stock felt almost off in one piece.
The stock black bass port damper felt is intact. It is the smooth black square on the left side, center position of the cup. I peeled this off in one piece and saved it for later use, if needed. Paxmate Plus was applied to the cup bottom and sides. On the driver picture you can see the "naked" rear side (cup side) after the stock white felt was removed; and the plasticine in the baffles.
On the left side you can see the reflex dot on the center grid of the driver. It is nothing more than a clear plastic furniture bumper with adhesive back.
On the right side you see the Paxmate Plus. Look closely at the piece of Paxmate just to the left of the center compartment and notice the notch cut out that exposes ~ 4 mm of the top bass port slot. The other 3.75 of 4 slots are sealed with this piece of Paxmate.
In this photo you see a felt square glued over the reflex dot and rear grid of the driver. Note to noobies: Very carefully lift the baffle and peak underneath to see where the wires run so you can position the baffle and open cup on your workbench without stressing the delicate solder points on the drivers - the orange area with the red and white wires.
Here, the baffle has been screwed down to the cup. I fashioned a donut of Paxmate Plus to provide a better seal under the ear pads. It's not pretty, but it is functional. I had a heck of a time making this ugly donut. I ended up using the ear pad as a template to make a "pattern" from a sheet of stiff paper that I placed over a piece of Paxmate. Holding it in place over a piece of cardboard, I used an xacto knife to "saw" or "punch out" the donut. Note the "pressure equalization vent" at 1 o'clock and that the donut does not cover any portion of the driver under the dust cover.
"Software" - From top left to right: blue felt, furniture bumpers, various glues, Claytoons 483 gram plasticine, 2 pieces of stock white felt removed from back of drivers, akasa paxmate plus, velcro with adhesive backing, 2 pieces of stock bass port felt, plastic furniture bumpers for reflex dots, black felt and electrical tape, felt furniture protection pads for reflex dots, box of spare parts.
"Hardware": T50RP's waiting for mods, Shure 840 ear pads, hot glue gun, and a some tools.
Not shown (yet) is my set of Smeggy Thunderpants awaiting driver transplant surgery and two more sets of T50RP's.
Radio Shack Sound Pressure Level meter with headphone adapter made from a DVD clear plastic spacer and duct tape. When in doubt, duct it! Set to Fast response, C-weighting, and 90 dB.
Edited by bluemonkeyflyer - 9/20/11 at 2:46pm