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I am using an SM57 to record my guitar cabinet. At random times during a recording the volume level will drop signifigantly (like -10 dB) and randomly return to its normal level. It generally does not stay between the two extremes. Also the line can get a little noisy when this happens (not a lot like a loud hum, but noticable enough where it is annoying). I am not moving around or adjusting the cables, mics, or preamp levels when this is happening.

I have tried to isolate the mic, cable, and preamp by trying different combinations, but I can never seem to duplicate the problem when I want it to happen.

Sometimes I can play for an hour before it is a problem, and other times it will go back and forth more than twice in a minute. Every time I have tried to run tests using just the preamp, just the mic, or just the cable with other mics, cables, and preamps I can never duplicate the problem.

Does anybody have any experience with a problem like this and what it could be?

I hope it is the cable since it is cheaper to replace than the other pieces.

Comments

FlyBass Fri, 02/13/2009 - 19:54

Sounds like a bad connection somewhere. It could be the cable or a jack on the mic or preamp. Corrosion builds up on potentiometers. Things heat up and expand. Just the weight of the cable can add stress on a connection.

Is it a problem with the interface or computer? Are you running other programs when you have this problem? Maybe something is stealing cycles from your processor. USB connection? Using your internal drive for audio files? Slow drive speed?

Experiment and test.

anonymous Sun, 02/15/2009 - 08:36

It may be a bad connection. I have no idea at this point.

As far as the interface/computer is concerned there is no problem. It is an 8 channel interface made be presonus and only occurs on this one thing. Many times we will just be using the interface as a mic preamp for jamming and only his cable/mic combo will have the problem while the rest is okay.

The only thing I know to do at this point, is to buy a new mic cable and put the old one in the closet and hope this doesn't happen again. If it does then I will have to determine if it is the preamp or the mic. Cables are much cheaper.