Tobias electronics - intermittent buzzing

[kesslari]

My Tobias (pre-Gibson - that's Bart TCT, right?) started buzzing in active mode tonight. Passive it's fine. Active - it buzzes. Sometimes, and sometimes it's OK. Over 30 minutes of playing, it was about 15 buzz, 15 buzz-free (counted from the time the buzz started)

Anyone encounter this, and/or got suggested solutions?

 

[BassLand]

It is possible that your mid module (small square potted block connected to midrange control) is not in the proper position. Is the buzz more pronounced when you turn the mids up?

to test, try moving the bass 90 degrees on both planes (twist the body 90 degrees, then rotate the bass neck 90 degrees, horizontal to verticle) notice how the buzz is affected. IF this is the case an external magnetic field is affecting the bass preamp.

The solution (if this is the case) is to shield the module (wrap in copper foil) and turn it 90 degrees (from the position of most noise) inside the cavity. Other possible causes are internal caps may be bad. Does this happen in one particular place? IF so there may be a motor or other appliance that sends out a signal that the preamp mid module picks up.

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