A few years ago I stumbled onto a thread here,
viewtopic.php?f=5&t=66746 covering a beyerdynamic M-380 capsule replacement suggesting the element at the heart of the mic was also used as the driver in the 600 ohm version of the beyer DT-770/880/990 headphones. Inspired and unable to afford a real 380, I decided to make my own. I Just finished them a few days ago, pics and saga below.
The project was simplified when I found a seller with 2 matching, unused bodies (they said beyer said they're 380, but they look like opus 65, same difference?) There was no felt on the capsule mounting frame, and the little shockmounts for said frame were missing. I was able to get a good look at some in a dead TG-x50 I got on the cheap, but unable to easily source them, I decided to just make something. I cut a Y shaped piece out of a neoprene mousepad and z-folded it to get sort of the same effect. Some screws were missing also, but the "HarDware" store had some that worked. M-2.5-0.45 x 6mm for the shockmount attachments. Same thread but a slightly shorter countersunk screw is what's used on the top of the body to secure it closed (I had the originals but this might be useful info)
I got some used 600R DT-XX0 drivers, the two I ultimately used are not from the same pair, but one DT-770 and one DT-880. Different color plastic, slight difference in magnet shape, measure the same DCR and sound the same on initial listening anyway. They needed some cleaning up as hair found it's way to them. Lots of alcohol, and lots of isopropyl alcohol and some gentle cotton-swab and toothpick action got them cleaned up, and they fit right into the capsule frame used in the mic bodies. Reassuring.
A crafty friend donated some felt, and after much indecision I attached it to the frame with Tacky (PVA) glue, as it has potential to be forgiving should I need to make changes down the road. It's bonded nicely. I attached the metal diaphragm cover the same way. Spread the glue carefully with a toothpick to thoroughly cover just the appropriate surfaces.
The TG-x50 had a small foam strip attached to the sides of the capsule frame. It looks like it's 1/8" x1/4"wide, but I had 1/4" x 3/8" on hand so I used that, for now anyway. It's the wrong color and you can kinda see it through the grill where the halves of the body meet, but whatever. Images I found online show a piece of felt covering the rear of the element also, so I glued a piece there as well.
Soldered up wires to the capsule. Fucked up and pulled one of the tabs breaking the connection with the coil wire, which is damn near invisible., but recovered successfully and got it located and reconnected without issue. If you do this, turn down the heat on the iron a bit and be careful. It's worth noting the real M-380 has a humbucking coil, which the above referenced thread indicated made no notable difference when omitting. Not finding any info on said coil, I decided to omit it as well. All wired up, stuffed a piece of the white felt from the headphone remnants into the neck of the mics and closed them up.
They work! I don't have a real M380 to compare with, but they pass sound, have a nice strong output and seem to exhibit the extreme proximity effect, and are certainly fig-8 pattern. I haven't recorded any samples yet, but will try to at some point to share.
Finding the mic bodies made this a much easier project, but it could totally be done without. Some more serious hardware hacking might be necessary, but the open-back DT-880 can housing could probably be modified to make a functional, round version which I suspect wouldn't alter the functionality significantly. I didn't have to go that route, but I'd be interested to see/hear the results if anyone does.
I originally detailed this project in a different (gasp) forum
groupdiy.com/threads/beyerdynamic-m380- ... rts.68413/
