I've got a mid-late nineties (pre Korg, post Marshall) AC30/6 TB and I've got a bit of an issue with it.

Now, the amp sounds fantastic and I absolutely love it... except for one thing. It seems that the tremelo channel bleeds into the brilliant channel. I don't know exactly how to describe it, but I'll try. There's a sort of... thumping that gets much more pronounced as I turn the volume up. Below about 1/4 volume, it's barely noticeable, but above that it gets pretty bad. I was wondering if there's any known quick fixes for this (didn't find any on googles) or if it's something that I just have to leave with (please, don't tell me that) or if I should take it to a tech. I'm also curious what would cause this.

Thanks in advance.
i have the same exact amp. i had a similar problem with mine. take it to a tech and he will most likely change some caps and a pot. the problem with mine was the there is a capacitor that connects part of the clean side with the tremolo and when it blows you get that problem. when you turn your volume up the cap gets more signal pushed through it, thats why it gets more noticeable with higher volume.
a legitimate AC30 6 TB, not a CC or a handwired model? The one with six inputs? Cause... if that cap were the case, I can't understand how the schematic would lay out that the tremelo would somehow connect to the TB channel, when the tremelo channel is a seperate channel... I'm'a use my marshall footswitch to try and see if I can kill the tremelo channel (I was told this does it) by switching it off, if that doesn't work, I'll take it to a tech. Just seems terrible that I go away to college after 3 years and NOW my amps decide to dive on me.