2. amps-preamps
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Hum on Tube Amp - Can't find source

I have a hum (60hz) I can hear on my speakers and it happens with my tube monoblocks (either of them).  With or without interconnects, it even happens on either amp (have tried one at a time) with every circuit on the house tripped/disconnected, every other component disconnected from the wall (including the Internet/CaTV line) and no interconnects.  

One amp has it as soon as it warms up whereas the other one is intermittent.

Hum X doesn't solve it, iFi Ground defender either, AVA HumDinger on powerline  doesn't solve it either.

I have replaced the tubes and both amps were just tested at the factory.  Replaced the circuit breaker, tightened every wire on the breaker box, checked and cleaned all connections to ground rod.  Added a hum eliminator to the internet line.

Hum cycles a bit with the tube glow matching the cycles.

I'm waiting on the power company to come check the power coming to the house.

Thoughts?

ervikingo
lowrider57's avatar
lowrider57
5,417 posts
 

Have you tried using a cheater-plug? It removes the ground from the circuit, this will check for a ground-loop.

lowrider57's avatar
lowrider57
5,417 posts
 

 

ervikingo OP
152 posts
 

Thanks for input! Yes I have. Cheater plug, HumX ground loop eliminator, iFi ground defender. Noise still present.

happens with interconnects out of each or either monoblock.

cables are lifted, separated. No dimmers on the home.

fuzztone's avatar
fuzztone
5,598 posts
 

Sounds like you have exhausted possibilities. Anyone who doesn't know what a HumX is unlikely to suggest any real solution. HumX works about 75% of the time for my unrelated issues.

Good luck. Are they noisy at any other locales? Hard to believe that they are at the factory. Proof?

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