KM84 low output suddenly

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

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

BluegrassDan

Well-known member
GDIY Supporter
Joined
Mar 17, 2009
Messages
507
Location
Elizabethton, TN
Hey folks. I was playing at Bonaroo this weekend and using my KM84s. Everything was fine during mic check.

A bolt of lightning struck VERY close to us. Sounded like a rifle - flash and bang at the same time. One of the KM84s stopped working (there is very low undistorted signal). No other equipment was damaged.

I got them home, swapped capsules, and determined the capsule is fine.

I'm not saying that the lightning caused the malfunction - could have been coincidence - but could something have been damaged due to high SPL? Could this cause the FET or one of the old tanatlum caps to fail? Is there a particular area I should zero in on?
 
Hi,
i would check C8 and C5 first...
but as you have a working one, replace the capsules by two 100pf capacitors and inject a 1khz sinus into both mics, then follow and compare the signals (with a scope or even with a voltmeter) to find the culprit

regards
 
If the failure is anyhow connected with a bolt of lightning, than it's possible that HI Z part of the circuit is dead.  I guess that fet can be the victim. Anyways, as granger.frederic suggested try with injecting signal through 100p .
 
Seams like the same problem a friend of mine had some months ago.
We changed the FET and everything works as it should.
Like Moby already said.
 
Back
Top