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Tube Question

I have an amp that has Russian Tubes. This amp purchased in the 90's has always had a hum to it which when playing music isn't heard. I'm thinking of buying 1 6SL7 and 1 6550EH tube to swap out and see if I can find if one of the tubes is the problem. The 6SL7 is Sovtek and the 6550EH is electro-harmonix. Should I replace with a similar tube from another company or continue with the same company? Is this approach to finding the problem sensible or a waste of time?
128x128jcbach
invictus005
597 posts
 
@lewm My experience proves it. Had an integrated tube amp which used 6SN7 tubes. Ordered brand new Sovteks from Parts Connexion at the time and they hummed so bad it was impossible to listen to music. 60Hz hum and noise/buzz on top of it.

Replaced them with JAN 6SN7 and it was so quiet you’d have to put your ear to the tweeter to even hear the faintest of hiss.

Yes, garbage Russian and junk Chinese tubes can hum.

I had a similar experience with 300B tubes and many others.
jcbach's avatar
jcbach OP
46 posts
 
Thank you for all your suggestions. lewm the sound is through the speakers. I've been told that tubes after 10 years should be replaced as they might draw way higher current and create a stress on the power supply and create hum. I've also been told that transformer noise is mechanical noise and would not be heard in the speakers. It seems like replacing the tubes is the initial way to go as the tubes I currently have don't seem to get high marks anyway.
tkr
100 posts
 
10 years! Seems that it´s time to replace the tubes, no doubt about that.
lewm
12,460 posts
 
I've said all I can say. Good luck.
atmasphere's avatar
atmasphere
11,577 posts
 
6SL7s made in Russian often have leakage problems (this is a test on a tube tester) which can introduce hum. We've had such troubles with Russian-made 6SN7s (which are similar but less gain) that we've had to recommend on our website to simply not use them.

OTOH I've yet to see a Russian power tube do that. So yes, you can use other tubes and I recommend it. I would make sure though that the new 6SL7 you use is tested for no leakage on a good tester.
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