Champ 600 Noise. What is it?

[dqami]

I just picked up a used 600 off Ebay and I'm noticing an ugly distortion coming from the amp when playing the 5th string A when volume is at 8 and above. It sounds like a blown speaker but I hooked the amp into a cab and it makes the same noise. I swapped tubes out also and same thing. Does anyone else have this issue or know wth is going on? I emailed the seller to see if he has the original sales receipt as I know Fender has a 5 yr warranty. On a side note, would swapping the cloth void the warranty?

[metropolis74]

I'm curious about this too and hope some of the Champ 600 gurus chime in. Not trying to hijack the thread I got a new Champ 600 last month and had a noise problem that appeared after my first day of playing it. Then after the third day and breaking it in more, the noise magically disappeared (knock on wood). The noise only occured when playing the low E open and through the first 5 frets and volume at 8 or more. It was a gritty sizzle sound that happened whenever I plucked that string on those frets. Is that the sound you are hearing? Like the OP, I tested it with diferent speakers tubes and still heard the noise. Then I tried a floor model Champ at GC and yep same noise. Mine doesn't make the noise anymore right now, but if it comes back...

[Yoni]

uhhh it is a TUBE amp.

[Teleholder]

I had that same problem and it turned out to be a loose tube. Just making sure the tubes were seated in the sockets real good and tight cured it.

[dqami]

No receipt so no warranty so I guess it's ok to mod. Well I just did the R19 and R7 mods and low and behold, the noise is gone. I'm not sure what cured it as it also went away when I tried a different guitar. After the mods, I went back to my original guitar and it was still gone. Don't know why and at this point, don't care :)
If you haven't done the 2 mods I just did, try it. It will totally transform the 600 into a beast (and swap the grill cloth).