feedback

Lately my upright bass, equiped with a piezo mic has started feeding back like A MFer. I'm runing it thru a red knob fender head with a mesa cab. I've tried everything. Would a preamp help? Anything?

[font=trebuchet ms]Feedback happens when soundwaves from the speakers cause vibration in the instrument, which adds to the signal going into the amp, coming out of the speakers, causing vibration in the instrument....

Short of trading your bass in for a solid-body (less acoustic sensitivity to sound around it), you have to find a way to isolate your instrument from the speakers. Pointing the speakers a different direction, moving further away from the speakers - whatever it takes.[/font]

You could try a gate or a feedback destroyer. Behringer make cheep rack mounted ones. I bet any sort of gating, downwards expansion guitar pedal would do the job like a Boss NS2.

Another think to try is a kill switch (you can use an A/B switch). Kill the signal to the amp and the cycle is broken. End of feedback.

Thanks Lord and good Doctor,

MF has a cheap noise gate that I'll try first. If I have to I'll go back to the fretless acoustic that is easy to control with the onboard controls. The old blues dude I'm backing up won't like it though. Just not the same vibe as the doghouse. Peace my brothers!!!

Ive heard some very good things about ISP decimator noise gates.They have a pedal and a rack mount version...here

http://rocksolidamps.com/items.php?CA=12&UID=2005031806503571.98.138.177&Lang=