Beyerdynamic M380 from Parts

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

thecr4ne

Well-known member
Joined
Aug 26, 2016
Messages
239
Location
California
I stumbled onto the thread linked below on Electrical Audio's forum regarding capsule replacement for a Beyerdynamic M380, using the driver from a 600 Ohm DT-770/880/990 headphones a few months ago.

http://www.electricalaudio.com/phpBB3/viewtopic.php?f=5&t=66746

This week I managed to pick up both 600 ohm DT990 driver and a NOS M380 body (silver like the Opus 65)  for under $200 total on ebay.  The body is missing a few bits that the complete original mic has and I'm looking for some clear reference photos if anyone is willing to open theirs up and take a few. Namely, I need to get a better idea of the suspension mounts that bridge the gap between the capsule frame and the mic body.  Any other close shots of the capsule and a good description of the materials used on the capsule frame and the white foam pad on the rear of the capsule would be really helpful.
 
Here's only really small pic:

http://recordinghacks.com/microphones/beyerdynamic/M380

Not help you much, last time i repaired it probably 8 years ago, don't remember these details.
Anyway  also pretty long time ago i bought cheap electret condenser for the mike body to use with this transducer.
I forgot about that -  so thanks for reminder :D
I want to use a spare 600ohm driver i have and try it in the studio for many sources. Anyway another occasion i will get 250ohm and see how this will work.
 
Thanks. I had found that one already. Unfortunately it's not much help. I'm hoping someone on the forum would be kind enough to open their own and take some up close and personal pics of the suspension mounts.

 
This is the best I've been able to get, from an image in the electrical audio thread linked above, zoomed and cropped. looks like a small rubber yoke that suspends the capsule frame inside the body.  I've emailed beyerdynamic's parts dept, but have yet to hear back. 

rvhEXkU.png
 
So I ended up with 2x bodies for this, and managed to get a non-functional TG-X50, which has basically the same internal mounting and whatnot, so that's a good reference.

I got a pair of 600Ohm DT-770s that had some bad wiring and harvested the drivers. Working on piecing these together, and debating making the TG-X50 into a third (I got a DT-990 driver a while ago)

At this point, I'm trying to settle on a felt for the internal baffling, and whatever the fluffy stuff is on the back of the capsule that I've seen in some photos. I think I'll just fake the rubber shock mount bits with some neoprene or something, and I need to find the correct foam to surround the internal capsule mount/baffle thing.

I understand the real M380's have a humbucking coil, which I can't find any useful information on, so I'll probably do without it unless anyone can offer me some clarity there.
 
Pics below. DIY'ed some new shockmounts from a 1/8" thick neoprene mousepad made a little y shape and accordion folded it to sort of be the same shape as the original. folded the top and bottom in opposing directions so it wouldn't twist to one side.

Also cut some felt, about 3/32" thick, not super dense, but it's what was available. Not sure what to glue this up with.
Also need to figure out the felt that goes on the back of the capsule in the M380. Pics and info are scarce.

Capsules pictured as well. These are drivers from 600 ohm DT-990 (black) and DT-770 (white) headphones.


fvPxCzQ.jpg

CLkoM1K.jpg

vQ3Mf90.jpg

1YWaUlv.jpg

oIUlpEb.jpg

EvRf4KB.jpg

5bxLuWe.jpg

MXhsnLK.jpg




 
Good news. I found a pile of "e-waste" at work that happens to be in the form of a few sets DT-770 cans with 600 Ohm drivers. Wish I hadn't already over-spent on some on ebay. Maybe I'll experiment with some as mics maybe some will live on as headphones.
 
OK, After a long stall, a pm response to this thread got me going again and these are DONEish. The only real stumbling blocks were choosing glue to attach the felt, and finding suitable hardware to replace what I was missing...and everything else I work on intermittently.

I chose Tacky glue (PVA) as I wanted something rather forgiving long term in case changes are needed. Using a toothpick I made sure every contact surface was covered and attached the felt. I also used the same method and glue to attach the perforated metal protective grill to the plastic capsule frame. There's a really thin edge here, but it's doable (and advisable to do before installing the capsule). I also cut a circle of felt to cover the back of the capsule, as there appears to be something similar in photos of the real M380. A few small dabs of glue to hold in in place.

Regarding hardware, I actually remembered to take a screw with me to the "hardware store" which, as it turns out, had matching screws. In the "Specialty Fasteners" section I found 2 packs of M2.5-.45 x 6mm machine screws which fit the mounting holes, both for the internal shock mounts, and the two holes at the top of the body which hold it together (though those are countersunk and I already had the originals). The hardware that holds the capsule frame to the shock mounts is a screw and nut, so I just dug around and found some that would fit and used those instead of bothering with an exact match.

In the dead TG-X50 I git, the capsule frame has a strip of foam tape, like weatherstripping, sort of, on the outer edges. It looks to be about 1/8" thick by 1/4" wide, not an off the shelf size I don't think but I had some 1/4"x 3/8" weatherstripping on hand so I used that, for now anyway. It's a sort of tan color and since it's too big, it conflicts a bit with the foam windscreen, but not enough to be a deal breaker.

So once everything was otherwise assembled, all that was left was to solder and close them up. The coils on these capsules are super fine wire, and too much heat from the iron along with some foolishly applied pressure meant I popped one of the solder tabs completely off and broke the connection to the coil. I was able to locate the end of the wire and successfully re-solder it, but don't let that fool you into any sort of security. That wire is so fine it's nearly invisible and I thought I was going to melt it altogether when soldering. Frankly I'm amazed it worked. Just turn that heat down a bit and be really careful if you attempt this. Also, it's worth mentioning here that the real M-380 has a humbucking coil, which I can't find any useful info on, and the thread I referenced in the OP omitted it and noted no significant difference in performance, so I've gone ahead without it here as well.

Once I got everything soldered and confirmed connection, I stuffed a but of felt left from the headphones into the neck of the bodies as shown in other pics, and closed them up. And...They work! I don't have a real M-380 available for comparison, but they have an obvious fig-8 pickup pattern and a proximity effect that seems to correspond to descriptions out there. Oh yeah, I made a pair of these, hence all the plurals. I'll throw in some pics below.

This is totally doable, but I realize getting the bodies is a huge setback and I'm lucky to have found some. I'd think with some more serious physical hacking one could adapt the cans from the headphones to work for this, and the open-back models like the DT-880 would probably be better than the closed DT-770's. But otherwise the only difference would be shape, and a stand mount would need to be worked out, but it could totally be done.

I may still change the foam stripping to the right size if I can find it, and I have a sheet of foam I may use to cut some fresh pieces fort he grills.

Finished product
kaCfZqj.jpg


Inside rear, Attaching felt
jCnG9O3.jpg


nurXOPo.jpg


Screws (philips are new slotted original)
tBlnFwV.jpg
 
Looks to me like a damn fine job! Any chance of some audio samples in the near future? Well done!

Thank you kindly. As for samples, I'll see what I can do. I'd need to do some excavating in the garage to access a Kick drum or a bass amp, so those might not come any time soon. I have a guitar amp handy I could mic, and will try to do some sweeps with rightmark if I can remember how to use it. Will put them here when I get around to it. Sorry for the suspense.
 
Highly clinical sweeps. Test done in untreated bedroom, Mic on stand in front of speaker (Tannoy i8, rated +/-3dB 85HZ-22Khz, so not the full picture re: low end) Sweeps done with Rightmark Audio Analyzer free version 6.4.5. "Close" is about 1inch from speaker Grill, "Far" is about 3ft away. A and B represent the two mics.

KMZlrtt.png
 
Interesting curves, Chris... would be fascinated to see what it was like with the mic situated at that magic point where the proximity effect kicks in.
 
Oh it's there. Sorry for not being more careful to align things properly, I'm not super familiar with the software, and the gain staging was different for the Close and Far sweeps. If the "Close" curves are shifted upward about 5dB to alight things better in the high end range, you notice the Proximity effect starting around 1-2KHz and really taking off at about 600Hz and leveling off at ~10dB higher at 200Hz before the limitations of my setup start to make themselves apparent below that. Again this wasn't done very scientifically, but I'm impressed with how closely they approximate the published curve shown here.

1620430241967.png

and here:
http://recordinghacks.com/pdf/beyerdynamic/m380.pdf
 
Last edited:
very interesting. TGX50 was my favorite kick mic back when the AKG D112 was the default everywhere.
Still have my 20+ year old broken TGX50 in a shoebox.
Curious why the 600 ohm driver is specced over a lower impedance which would be more typical of 'pro' dynamic mics. Which tend to be 100-200 Ohm. DT770s come in a bunch of impedances!
 
The element in the TG-x50 is way different, so I'm not sure what would be involved in getting it back to sounding the way it should. That said, the hardware necessary to make it into this flavor of M380 with the headphone driver is there, plus some added stuff the M-380 doesn't need, so you might not be able to recreate the TG-X50, but you could at least make it into something else cool.

I don't have the greatest grasp on impedance matching/loading, so I can't contribute anything useful as for why 600R and not 250R. That said, the 250R versions of the DT-770/880/990s seem more common than the 600R, soooo maybe we should try it? I still have a TG-X50 body, I'll keep my eyes open for cheap set of older used 250R cans.
 
Last edited:
The last picture in post #6 shows the capsule with hair and dirt on the slightly sticky membrane. I'd pluck that off - it may work for kickdrum but the hair will resonate in front of a bass cab on certain frequencies and will create buzzing. The condition of the capsule is typical for those that were in headphones. Try to use non-magnetic tweezers, the magnet can pull down the tweezers and you don't want to damage the membrane. I hunted down headphones for capsules for a few years but found the ratio of fully working capsules to half dead capsules isn't working for me, about 50% were unusable and 90% too dirty for full use. If you record a frequency sweep you can find out if a capsule is buzzing, some do even if there's no more hair and dirt visible, i suspect there's dirt in the magnet gap which got in from behind, where these capsules mostly have not much to prevent that.
For the missing humbucking coil in the mic: it is not that big an issue. I have an especially bad transformer to test equipment shielding and checking M380s with or without humbucking coils it makes a difference if you get closer than 10 inch, otherwise I wouldn't mind.
I dug up a source of new old stock, completely unused capsules that were sitting in a warehouse in southern europe from an OEM deal Beyer made with Revox and started to fix broken M380s. Steve Albini bought two and is happy with them - he should know how these things are supposed to sound.
 
Ive used the M380 also , its a good mic on guitar cabs if you want a different tone to the usual 57 or 58 screech , used it on kick drum also in conjunction with a duvet tent at the back to reduce the rear lobe room pickup and reduce bleed in the high end especially , now you have a lot more scope to eq the bass drum without extraneous sounds creeping in .
 
The last picture in post #6 shows the capsule with hair and dirt on the slightly sticky membrane. I'd pluck that off - it may work for kickdrum but the hair will resonate in front of a bass cab on certain frequencies and will create buzzing. The condition of the capsule is typical for those that were in headphones. Try to use non-magnetic tweezers, the magnet can pull down the tweezers and you don't want to damage the membrane. I hunted down headphones for capsules for a few years but found the ratio of fully working capsules to half dead capsules isn't working for me, about 50% were unusable and 90% too dirty for full use. If you record a frequency sweep you can find out if a capsule is buzzing, some do even if there's no more hair and dirt visible, i suspect there's dirt in the magnet gap which got in from behind, where these capsules mostly have not much to prevent that.
For the missing humbucking coil in the mic: it is not that big an issue. I have an especially bad transformer to test equipment shielding and checking M380s with or without humbucking coils it makes a difference if you get closer than 10 inch, otherwise I wouldn't mind.
I dug up a source of new old stock, completely unused capsules that were sitting in a warehouse in southern europe from an OEM deal Beyer made with Revox and started to fix broken M380s. Steve Albini bought two and is happy with them - he should know how these things are supposed to sound.
Capsules were thoroughly cleaned before installation. Careful use of toothpick, cotton swab, and some alcohol got the job done. No resonances. I did damage one membrane when removing the capsule from the headphone mounting frame, stuck to the backing and couldn't save it. It was a newer headphone driver, which I was curious about as it had 3 solder tabs, but RIP.

I think I just sent you a message on reverb. The mic you have posted there doesn't have the felt on the capsule frame nor behind the capsule itself, it also doesn't appear to have the protective metal cover over the front of the capsule (this part comes in the headphones). Does it make a difference? Do you have sweeps of yours to compare? Curious if there's a difference in off axis rejection or top end response. Do you have more bodies or just more capsules?
 
Back
Top