I'm having an issue with my (new, chinese built) AC-30 CC2. It's got the standard Vox GHS speakers. So here's the issue: Recently, the amp started making a noticeable buzz/crackle in the left speaker when playing the bottom 5 notes of the guitar (and ONLY the bottom 5 notes). This problem is independent of volume (occurs at low and high volume) and independent of amp settings (tried all sorts of settings to see if it would change). My first assumption was a blown speaker as the crackle was coming from a single speaker. When I played the offending notes and applied pressure to the back of the speaker cone with my finger, the problem stopped occurring. So I took the whole damn amp apart to get the speaker out (most difficult amp I've ever seen to work on) and, to my surprise, no tear anywhere to be found. The speaker is in perfect condition. Could this be a tube issue? I really don't know much about amps and I don't want to go buy a whole new set of tubes if it's not likely to be the problem. Any help from the knowledgeable folks here would be greatly appreciated. Cheers, Tyler P.S. Sorry if this post is a bit jumbled. I'm quite pressed for time at the moment. Thanks again!