A few questions

[thunderbird32]

I bought a Coliseum Bass from ebay recently and I've got a few questions. The first is that occasionally I hear a crackle or pop. I've checked the cable and I don't think it's my bass either. And I don't think it's the speakers since the cab is brand new and if I turn the amp up it doesn't get worse. Any ideas?

Also, when I turn the amp on I get a loud *whump* sound. Is it usual for this to happen? It won't damage my speakers will it? I only ask because I've never had this problem from my guitar amp and I'm curious.

Lastly, the treble knob has come loose. It feels like it's only held in by the wires. How difficult is this to fix? Can I easily do it myself?

Here's a picture just for fun:http://i185.photobucket.com/albums/x181/thunderbird_32/IMG_2950.jpg

[basiklybass]

The whump is common on large amps and I have been told many time, and read in manuals, that it is normal. I don't like it either and watching my speakers jump make me be concerned for them as well...but so far I have not blown one.

The crackle is not normal and should be investigated. There are many causes but the most common is bad soldier joints or loose connection on the board. We have heard many times on this forum that someone took out the chassis, took a close look and found some bad joints. They fixed them and solved the problem.