When I have my bass plugged into my amp and dont touch the strings I get a sound of feedback, like a very low buzzing noise, but then stops when i dampen the instrument. I use a small Balcat Bass Amp for in my bedroom, and have a Nirvada copy of a standard Fender Bass guitar. It has made this noise ever since I bought it, which was in top condition from Cash Converters for £99. I've tried swapping leads and the noise still persists. I have never noticed the sound when practicing with my band, I simply havent listened out for it. When practicing with the band I have a larger amp. The sound doesnt stop me from playing but its annoying.
I will try and spot it next time I practice with the band. My brother said it may be interference with other things plugged in on the same 4-way adaptor plug in my bedroom. My friend says it may be the connections within the Bass, but I took it apart before and saw nothing wrong with it, although there were a couple of wires that overlapped.
Just to mention I have taken it apart a couple of times to modify it.
But the problem was with it beforehand. I know the money back guarantee doesnt quite stand up for itself now...
How can I fix this problem? I noticed on some guitars that they have more than two pickups which I imagine enhance the sound quality of the instrument. Do I have to buy and fit another set of pickups?
feedback type noise... 
