2. amps-preamps
  3. 181284-111795

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

Showing 3 responses by jea48

jea48
4,733 posts
 

 

@holmz
 
 
 
 you beat me to it...

 

@dpop

It kind of sounds like a low frequency motorboating oscillation.

This may be off the wall, but I seem to remember reading a thread several years ago, can’t remember if it was on Agon or AA where a guy was having an oscillation problem with a tube amp. Just going from memory someone asked what speaker wires he was using. What ever manufacturer, type, speaker wire it was it was causing an impedance mismatch for the output transformers for the amp. If it was here on Agon I would bet the Late @almarg chimed in and was the one that solved the problem.

Might be worth it to try a cheapo zip cord 14/2 cable and find out for sure.

jea48
4,733 posts
 

I have had good luck with The Tube Store over the years.

jea48
4,733 posts
 

@ervikingo

The 7044 tube is the Driver tube...

I would strongly suggest you tell the vendor you buy them from you need each section of the Triode tightly, closely, matched. Pay extra for each tube if you have to.

I doubt you will get that from Amazon.

.

More to discover