Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Hi. My friend's Rumble 100 bass amp suddenly, overnight, has developed a problem and I have been asked to troubleshoot it. The sound with a bass or guitar is totally distorted and loud, and this distorted sound exists with ALL of the controls set at ZERO. I've attached an MP3 file of a few seconds of strumming a guitar plugged into the amp. I have already tried disconnecting the internal speaker and hooking it up to my guitar amp and it sounded fine. I opened the amp up and all I found that looked suspicious was a 10k resistor on the power supply that looked like it had gotten hot and was leaning against a .33uf safety cap (I've since straightened it up). Both components tested good in circuit, well within tolerance, and they also tested good, well within tolerance, after I removed them from the board. Where do you suppose that I should start looking next?

Possibly a bad Volume pot R11 or cracked solder connections on this pot.