#1
My friend bought a 6505 212 combo a few weeks ago that needed new power tubes, whenever you turned it on the blue glow from them would flicker (especially from the left hand side when looking from the back) and a crackling sound would come through the amp. Well a few hours ago he bought new tubes to put in the amp and it has the same problem..?

We swapped around preamp tubes when he first bought it and that didn't affect the problem, and the flickering made me think the power tubes were near the end of their life. But apparently I was wrong.. thoughts?
Endorsed by Dean Guitars 07-10
2003 Gibson Flying V w/ Moon Inlay
2006 Fender All-American Partscaster
SVK ELP-C500 Custom

1964 Fender Vibro Champ
1989 Peavey VTM60

[thread="1166208"]Gibsons Historic Designs[/thread]
#2
yep...something's definitely wrong.
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#4
It doesn't affect the volume whatever the problem could be, you can crank it and it's fine. Just has a very noticeable crackling noise that comes through, even without a guitar plugged in. It's not the inherent high-gain white noise either.
Endorsed by Dean Guitars 07-10
2003 Gibson Flying V w/ Moon Inlay
2006 Fender All-American Partscaster
SVK ELP-C500 Custom

1964 Fender Vibro Champ
1989 Peavey VTM60

[thread="1166208"]Gibsons Historic Designs[/thread]
#5
try this and report back

http://s545.photobucket.com/albums/hh384/buckethead_311/Amp%20stuff/?action=view&current=Microphonicpreamptube.mp4

it will be a bit harder due to it being a combo and pre's not as accessible.

try pre and power tubes

otherwise, just hit all the tube pins with deoxit contact cleaner and tube roll the pre using process of elimination
Last edited by 311ZOSOVHJH at Dec 17, 2011,
#6
I tapped the pre's checking for microphonics and they were all alright. They're actually pretty easy to get to on the combo, unscrew the back cover and they're right there. To change them on my Jet City you have to take the faceplate off, otherwise it's impossible to get to V1 from the OT in the way.

I'll tell him to pick up a can of Detoxit, that was actually my next idea and it wouldn't hurt to hit my JC's sockets as well.
Endorsed by Dean Guitars 07-10
2003 Gibson Flying V w/ Moon Inlay
2006 Fender All-American Partscaster
SVK ELP-C500 Custom

1964 Fender Vibro Champ
1989 Peavey VTM60

[thread="1166208"]Gibsons Historic Designs[/thread]