Dynamic Mic Repair -- Help needed

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f0m3

Member
2013-12-09 6:37 pm
Hey,
after building a lot of guitar effects, electric guitars etc. i started to try to understand more on audio equipment. Please tell me if it is not ok to post here but i have the feeling there might the right people around here.

I have an 1980s akg dynamic mic D320b wich has a hubucking coil and a bass rolloff switch.
The mic is in a good optical condition and basically working but: the volume is low and there is no bass. i checked the basic wiring and even dropped out the bass rolloff switch (its just plugged in). Everything seems to be ok.

Then i checked the three solderpads outside of the capsule which seem to be +pol, -pol and humbucking coil(outside the capsule).
Theres a nice drawing in this old manual: http://lcweb2.loc.gov/master/mbrs/recording_preservation/manuals/AKG%20D-320B%20Hypercardioid%20Dynamic%20Microphone.pdf
When i measure the three solderpads i can see they are connected to each other as they should. But the across the diaphragm coil i measured about 300 ohms and across the humbucker coil only about 10 ohms. Could there be a problem? maybe a broken humbucker coil?

I would really appreciate some tips on this problem.
 
Sounds like the capsule has issues. I've worked on a few mics that have shown similar. For the likes of an AKG D12, the fix is possible, but difficult: you have to remove the diaphragm, clean it, and then re-align it. It's something I offer as a repair service, but there's no guarantee that the mic will be repairable.

My recommendation would be to start looking for new microphones. The EV N/D767a is a decent mic in a lot of ways, and can be had for sensible money on the 2nd-hand market. My go-to is the Sennheiser e935, but they're not cheap.

Chris
 
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