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Double Bass Ground Noise Issue ???

patas75

patas75

Jan 26, 2011
269
3
Apple Valley, CA
#1
I have a BSX Allegro and am having an issue with noise. The bass has a piezo pickup built in the bridge. From there it goes to a Bartolini preamp. When I have the bass plugged in to an amp, there is noise coming out, sort of like static. If I touch the input jack there is small pop and the noise goes away. Once I remove my finger it comes back. Could this be a ground issue or possibly a shielding issue? What steps would you recommend in trying to resolve the issue?
 
#4
I'm assuming that the thread is headed to the amps forum, but in the meantime...

I'm suspecting a grounding issue with your amp, or with the outlet that it's plugged into. Can you try another outlet in the house? You can get an inexpensive outlet tester at the hardware store. Or your amp could have a bad ground, in which case you have to be aware of the chance that something might be dangerous.

Do you get the same benefit from touching the output side of the preamp? If not, then there may be a dodgy ground connection just between the input and output jacks of the preamp. A bit of wire between the two jacks might help diagnose this. Anything that works, you can figure out later how to make it reliable long-term.
 
#5
Although this sounds extremely elementary, have you tried a different cable? It's not unusual for the substitution of a good cable to correct a problem like this. You are dealing with a very high impedance, very high gain circuit here, so the cable needs to be perfect. In any event, it seems there is a difference in potential between the shield/ground on your bass and the amp's ground. The question then is why that is so.
 

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