A little mains hum

For my home system I'm using tube power amps, hand-made in the US (for the Nonsuch 4s). They work well and I'm happy with them. However, there is a little mains hum on the left channel.

Now the strange thing is that if I turn off the right power amp, the hum diminishes on the left so there's some sort of interference going on there.

Any ideas what?

 

And if you swap the L and R pre-out >power amp inputs? So that L from the preamp goes to the R power amp etc..

I bet the interference moves. Or mysteriously vanishes

 

Sorry Graham, you lose. The hum is unaffected by the interconnects being swapped or, for that matter, in or out.

Still, you've helped me narrow things down - it's a power amp only thing, somewhere between the plugs and the speakers. I have managed to reduce the hum (but not solve the problem altogether) by moving the two power amps further apart.

 

Try Stillpoints ERS... :latte:

 

Hiya steve

Have you tried putting the power amps into an alternative wall socket to the rest of the hifi?

Sounds silly but made a difference at my gaff


Chris

 

Doesn't sound silly at all to me. I suspect an earth loop through the mains and preamp. Try connecting one power amp to one mains spur and the other to another.

 

I'd go with that too, just had the very same problem on an small a/v system we've been too recently, more common than you think.

 

Thanks guys. I'll try plugging an amp or two into a different socket. My wife loves mains leads trailing across the room anyway.

Longer term, I really need new and better mains leads and I will have a look at the Stillpoints ERS. I've just got to get to the Bristol show first.