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
hiend2's avatar
hiend2
376 posts
 

The substitution of the the 12at7 or Whatever might have something to do with it.

dpop's avatar
dpop
292 posts
 

@hiend2 

Try using an extension cord and plugging them in on other circuits

ervikingo has tried that already.

hiend2's avatar
hiend2
376 posts
 

I has a trouble in my preamp similarit was exposed to a Large Magnetic field.

Take the amp to your office,

Try a solid state unit...

donavabdear's avatar
donavabdear
477 posts
 

@ervikingo Hate to say it but I keep thinking about your neighbors WiFi transmitter system. 

I spent 20k on buying 2x PS Audio P20 AC regenerators and I still have a hum. Also it is rare that 60hz is the only frequency usually you get a lot of 120hz the harmonic. Test to see your ground and neutral voltage should be very low if it is anything above 1 or 2 volts that could be it. Also a new TV or radio station in the area. I love tube amps but I'm thinking they are such a pain. 

dpop's avatar
dpop
292 posts
 

@hiend2 

Try a solid state unit...

ervinkingo has tried that already, and the solid state amps don't hum. Please look back at some of the past comments.

@donavabdear 

I love tube amps but I'm thinking they are such a pain. 

I agree with you, and that's one of the reasons why I no longer incorporate them into my systems.  

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