Noisy studio 22+

[voodoo_child]

My studio 22+ is suffering from an uncontrollable howling feedback-type noise once the volume or either master goes past about 6 or 7. Its not feedback from my guitar, and im using quality cables and theres no problems with grounding on my guitar or anything. I can control it to a small degree with the 5 band eq, and bringing the regular tone pots down to zero completely eliminates the problem (but obviousy isnt a solution).

Any ideas about what could be causing it, in order of likelihood?

 

[voodoo_child]

Scratch that, i just replaced the first preamp tube and it completely eliminated the problem on the clean channel. The lead isnt perfect but is much better, i assume swapping a good tube in the remaining postions one by one will help.

 

[boogie-boy]

Hi !
I have about the same problem to a MK2c I have. The clean channel is perfect, but when i kick in the lead it gets crazy microphonic (like tapping on a microphonic tube, just all over the chassis, print boards etc.) and the uncontrolable feedback comes along with some ghost notes when I play single notes.

I have searched for what could be wrong for six years now, but no local tech I have found seems to be able to detect what is wrong. I have done a lot myself from advise from different people at places like this, but nothing has helped so far.

It is not a tube problem. I have tried countless (I have three suitcases of tubes) without help.

In my amp I think there is something wrong around socket V3.

Well Last saturday I left it with a fourth tech to look at it. If he finds out what was wrong I will let you know.

I just think our problems have to be related. If you find out what is wrong, please let me know too.

Stian
NORWAY

 

[welshboogie]

I think a lot of people will agree with me here, you cannot just put any tubes in a Boogie!! any sub-quality tubes will squeal like a pig in the high gain/sensitivity stages (especially V1).

If the squeals are across all channels and you are getting that ringing sound from tapping the front of the chassis then I suspect a poor quality V1 and (this is from memory) V3.

If you are getting Ghost Notes, then it could be a cap problem as well.

I would advise both of you to re-valve these amps with new high quality tubes - not sure what brands you can get but I am currently using a brand called Harma which are Cryo-treated to eliminate feedback - I have a MKIII and I can run it at high volume with Vol 1, Treble and Lead Drive on 10 with not a squeal in sight!!!!

I am sure BoogieBabies has some thoughts on this and will offer some more of his invaluable advice on this - respect Bro!!!

 

[voodoo_child]

Thanks for the reply. I replaced the V1 tube with a spare i had lying around and it more or less eliminated the problem. Mostly i was just worried that it was a problem with the amp itself, and i didnt fancy a visit to an (expensive) amp tech. Now im satisfied that it was simply a microphonic tube.

A full re-tube with a quality brand is on the cards for the near future (i bought it second hand and havent changed the tubes yet), for now, the amp is useable again, which will do until i have time to give it a full retube.

Thanks for the advice

 

[boogie-boy]

Hi !
Nice to hear you found out about it !

For my amp it is certainly not as easy. I have a suspicion on the V3 socket however, but that is a lot of work, so I will eliminate al other options first.

If Boogiebabies is the "chief tech" (every forum has one... ) here I would be very happy to hear from him about this problem. If you happen to read this and have an opinion, please write !

stian