Strange changing white noise from repaired amp

[Meddi]

Hi all,

 

Maybe a tech question. But I recently had one of my SET monoblocks fixed and ever since there has been a strange sort of fluffy white noise that changes. Almost as though is it something in the power signal or something.

 

When the amp was fixed the problem was a tiny thing that dealt with ac-dc apparently.

 

Any ideas? It was fixed very quickly at my request.

 

It is starting to drive me a little mad to tell you the truth.

 

Thanks in advance,

 

Rob

[ehtcom]

Hi Rob.

If it's only one channel.

Try swapping the small signal tube(s) from left to right to see if the noise follows.

I have had the noise you describe come from sus 6SN7's a couple of times in past.

Cheers, Earle.

[Meddi]

Hi Earle and thanks very much,

It's strange but only two days ago did I get a crush on your tempest monos and pre... Beautiful looking and layout. Would love to hear them.

So the wife is involved now... Turns out when I turn the pre off the noise goes away... So I opener her up:

Then replaced the right channel input tube (?) and the noise reduced drastically. But it is still louder than the left....?!... The amp itself is very warm now so will have to see how it fares when it's cold.

I really appreciate your input Earle.

Rob

[Meddi]

Seems strange though that the noise started as soon as the amp arrived home. The monoblock SET that is.

Edited October 23, 2013 by Meddi

[Meddi]

Actually, assuming the right input tube is on the right in the photo, the noise is the same now when all is quiet.

[Meddi]

Problem is fixed. Turns out that the tube on the left is the tube for the right channel. Replaced it and problem solved.

 

Thanks Earle, wouldn't have happened upon the solution without your input.

 

I'm in your debt.

 

Rob