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Tube Ampp Almarro low level hum

My Almarro 318B amp has recently developed a low level hum that comes and goes. I have swapped out all 4 tubes at one point or another and that does not change it. Once the hum stopped for a few days while I was breaking in a new paid (NOS) of 6C33C tubes. But it keeps coming and going. It gets a bit louder and then softer. If I tap the base of the amp, the hum stops. If I pick up the amp, it stops. If I knock the table where the amp sits, it stops.

I run the amp about 6-8 hours a day. Once a week I foget and leave it on all night.

Any ideas?

Thanks

Dan
mcmanus
mcmanus OP
82 posts
 
I placed weights on the transfomers and indeed that solved the hum problem. Then I tried using springs under the amp to isolate it and that solved the hum problem without the weights. Thanks for all the great advice to solve the problem.
jax2
3,031 posts
 
Glad to hear it worked out! The spring solution is a new one on me, but I've found the weights can work wonders.
mcmanus OP
82 posts
 
The hum came back after a few days on the springs. So the weight is the ultimate answer to this problem. I just need to find one that matches the ascetics of the amp :) Thanks.
dan480
6 posts
 
I sugest you contact Mr Muramatsu at Almarro and ask all this questions.they are so helpful,I am sure they can solve your problem.
Daniel
Australia
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