Bogen CHB 35A Always a bit Distorted

[Derwood]

Greetings,

My brother-in-law was over jamming and he was playing my bogen totally cranked. The next day I turned it on and it seemed to sound a bit distorted no matter what volume level I had it on. I switched speakers with the same results. I also swapped out the 12AX7 since I had one lying around. I am not sure if the running it cranked had anything to do with the current situation. It sounds like there is a tube screamer on with the gain up just a bit. It is smooth distortion and very subtle. It is there with different guitars.

Could this be a simple tube issue and swapping out the original tubes (1960's) solve the problem? Is is likely a preamp, power or rectifier issue? Should I not spend the money to get all new tubes (2x 7868, 6EU7, 6C4) and just take it to my amp tech?

Any knowledge would be appreciated.

Derwood

[tim]

It could be your power tubes or preamp tubes. One power tube may not be conducting properly. The only way to tel other than hooking it up to a scope is to replace the tubes and see what happens...

[Derwood]

It is actually not stereo. It is basically a three channel 35 watt head. The third channel skips one of the preamp tubes.

It has also gotten worse. It is now humming badly and has much less volume that before. Could it just be tubes or do I need to send it in? Tube replacement will be about $80.

Derwood

Here is the message that has just been posted:
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Not being familiar with your amp, I'm going to make an assumption that it's a stereo amp. If so, is it only distorted on one side or both...switching speakers to test the amp assumes that one of the speakers is good. If both speakers are blown, then swapping them would make no difference, it would always sound distorted...I guess we need a bit more information to help you out.
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[MWJB]

"Could it just be tubes or do I need to send it in? Tube replacement will be about $80." Could be just tubes depending on their age/history. Playing the amp cranked, by itself, should not have blown anything, so I'd be more concerned as to why the tubes/amp have gone down. Go straight to the tech, new tubes may help but if the problem is just a resistor going open it might be fixable for much less than the new tubes...plus if you don't know what the problem is, you'll still have to pay for the fix after buying new tubes if they don't cure the problem.

[Enzo]

Confused. Is there another discussion about this amp somewhere?

[Derwood]

Some one did reply to me off list between the first and second post. I included the comments in my reply.

Derwood

I am taking it in!