# Whats wrong with my amp? Peavey 6505+



## Diablo (Dec 20, 2007)

Ok, I hadnt used this amp in while (month or 2), went to try it and it seemed to be making a weird effect on its own. While I was playing, it sounded as if there was a mic plugged into it that someone would tap every 20 seconds or so.
Is this a tube problem? I changed the power tubes not that many playing hours ago, but havent changed the preamp tubes (previous owner did, but no idea how long ago). I rarely play at volumes over 3.


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## Stratocaster (Feb 2, 2006)

Wow that's a strange one.

Is there a chance you could have blown/damaged a speaker in your cab? That's the first thing that the tapping sound made me think of...

Keep us updated!


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## Diablo (Dec 20, 2007)

Stratocaster said:


> Wow that's a strange one.
> 
> Is there a chance you could have blown/damaged a speaker in your cab? That's the first thing that the tapping sound made me think of...
> 
> Keep us updated!


Anythings possible I suppose (the noise goes a way when I unplug the cab  j/k!) but I think its an amp generated issue, as I'm getting the "tap a microphone" sound even when nothing is plugged into the amps input.

One other thing I noticed is that power tube closest to the input/transformer flashes brightly when the microphone sound occurs (possibly the tube beside it as well, not certain).


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## ne1roc (Mar 4, 2006)

Your tube is definitely finished. Did you bias the amp when you changed the tubes the first time?


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## keeperofthegood (Apr 30, 2008)

Another cause of regular popping in anything electrical (and with being regular I would suspect this) are failing capacitors. The pop is the overcharge/discharge of the capacitor. The bright flash may be the moment of the discharge.


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## Wild Bill (May 3, 2006)

keeperofthegood said:


> Another cause of regular popping in anything electrical (and with being regular I would suspect this) are failing capacitors. The pop is the overcharge/discharge of the capacitor. The bright flash may be the moment of the discharge.



Yeah, you're probably right. The coupling cap feeding that tube is probably leaking. High voltage from the previous stage gets though and hits the grid of the following. This turns the tube on full, like a dead short. The tube makes like a firework!

Coupling caps are cheap! Replace them first and see if the problem goes away.

It IS possible that the tube is shorting all on its own, especially if it was never re-biased when the tubes were changed and the tube has been running too hot! Problem is, now if you just changed the tubes, if it's a cap problem the new tube will be damaged while you're waiting to see if it will flash! So I would definitely change BOTH coupling caps to the output tubes first!

If you don't know how to recognize which caps are the couplers, or even recognize a cap, then find a tech!:smile:

Good luck!

:food-smiley-004:


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## Diablo (Dec 20, 2007)

Thanks for the info guys. No I didnt bias the amp when I changed the tubes.

I wouldnt know how to change coupling caps either.

Bill, I take it you work on these things for a living, would you want to take a look at this one?


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## ne1roc (Mar 4, 2006)

Wild Bill is a great amp tech and worth the drive to Stoney Creek from Mississauga. He did a re-tube for my Carvin Legacy and it never sounded better!

:food-smiley-004:


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## Diablo (Dec 20, 2007)

ne1roc said:


> Wild Bill is a great amp tech and worth the drive to Stoney Creek from Mississauga. He did a re-tube for my Carvin Legacy and it never sounded better!
> 
> :food-smiley-004:


Cool, PM sent!


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## Stratocaster (Feb 2, 2006)

Instead of changing the tube, you can just give me the 6505 and buy a new amp:smile:...........:frown:


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## Diablo (Dec 20, 2007)

Stratocaster said:


> Instead of changing the tube, you can just give me the 6505 and buy a new amp:smile:...........:frown:


I think you've got enough amp to keep you happy for a long time 
I wouldnt call a 6505+ an upgrade to an EVH III, altho both are great units in their own way!


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## Stratocaster (Feb 2, 2006)

:rockon2::smile:


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