ValveKing 20MH issues

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GreenKamikaze7
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ValveKing 20MH Vari-Class squealing (on AB side...)

Post by GreenKamikaze7 » Sun Sep 05, 2021 7:57 pm

Hello all, new member here on the boards, long enough Peavey owner and user. Currently own and use a Classic 20MH for a clean & crunch, with a 6505MH for my all out shred face distortion tones. I picked up a used ValveKing 20MH yesterday that I wanted to A/B against the Classic 20MH with, and already have an issue with it....

The issue I'm having is that the aml sounds "gritty/grainy" or scratchy in the lead channel, and the clean does as well but not anywhere near as bad. The real issue I'm having is that the Vari-Class control gets this awful squealing noise when turned all the way clockwise... Im puzzled because it sounded fine when I played it in the store a few hours before I brought it home, and now this...

The TSI lights function properly - Red when in standby, green while on, and stay green in either channel or any other control position... i am also running the amp in 5W mode, as it's pretty much only being used in my house and 20W mode is obnoxiously loud...

So has anyone else encountered this issue??? If so, what was the problem? Bad tubes, or something else??? I have a spare set of tubes for the 6505MH I will try in it, but am waiting for the bias probe to show up before putting them in...

Any help and insight would be greatly appreciated. Thanks, and stay safe in these insane times we're all going thru right now!

UPDATE: Since this was approved and posted, I had put a new set of tubes in it and the only upside is that the squealing stopped...

The grainy/gritty sound still happens on the lead channel, and it's bad when using the effects loop... I even sprayed some contact cleaner in the jack ports for the loop, and still the same issue...

GreenKamikaze7
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ValveKing 20MH issues

Post by GreenKamikaze7 » Thu Sep 09, 2021 7:07 am

So I made an initial thread about the issues I am having with the 2013 ValveKing 20MH I just bought (used...). The problems I am having are:
*The amp sounds a little grainy/gritty on the lead channel...
*Grainy/gritty issue is made a lot worse when the effects loop is used.
*Vari-Class control has a high pitched squeal to it when turned all the way clockwise to the AB position...

So in a curious attempt to see if it was a case of a bad tube or tubes, I put a brand new set of EL84's & 3 good used 12AX7's in it. I had tweaked the bias to about half way per one of the other VK20MH threads where the owner was told to dial it in via the TSI indicator lights... While this did help to resolve the Vari-Class squealing issue, the problem of the grainy/gritty tone persists on the lead channel - and its more pronounced when using the effects loop.

And when I say grainy/gritty, I mean it sounds like some kind of signal interference that's causing the tone to be really choppy and not quite cutting out, but not the way the amp should sound... I've even sprayed contact cleaner inside the effects loop jacks and ran a cable in and out a few times to try and clean the contact points inside the jack, but to no avail...

And when swapping the tubes I checked the rest of the internals for anything that may be burnt or damaged, and everything looks okay...

Has anyone else had any of these issues with this amp? If so, what wound up being the resolution to fixing it??? Can anyone shed some light on what the issues could be to at least get me in the right direction???

Thanks!

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JamesPaul
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Re: ValveKing 20MH issues

Post by JamesPaul » Thu Sep 09, 2021 10:10 pm

I own both the 20 MH and the 20 combo. Unfortunately, mine do not have the "grainy/gritty" lead or the squealing issues. I know, not much help, but hang around and maybe someone will be along who can help.
Enzo wrote:I find if the amp is working, that is a good point to stop fixing it.
James Paul's Peaveys
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GreenKamikaze7
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Re: ValveKing 20MH issues

Post by GreenKamikaze7 » Sat Sep 11, 2021 12:15 pm

JamesPaul wrote:
Thu Sep 09, 2021 10:10 pm
I own both the 20 MH and the 20 combo. Unfortunately, mine do not have the "grainy/gritty" lead or the squealing issues. I know, not much help, but hang around and maybe someone will be along who can help.
Hey James!

Ah, no stress man... If worst comes to worse, I'll either sell it to the shop that will wind up repairing it (as he buys stuff all the time...), or salvage it for the tubes and parts for the Classic 20MH... I've already chassis swapped the Classic 20MH and ValveKing 20MH, so the Classic now has the black cabinet head & the VK20MH has the tweed cabinet head...

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