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What causes loud num noise?

I have an tube amp using SE connections and have followed manual for the exact way to set up the system. How come the amp produce a loud hum noise, just like standing at the back of a big television. The noise is independent to the volume control. I plug the amp directly to a wall power receptacle. I have used the same receptacle connecting to my old solid state amp and it works fine.
awchui
kchahoc
85 posts
 
Sounds like a ground loop. Try unplugging (with the power off to all components) one at a time and then turning the rest on to see which piece is causing the ground loop. If you still don't understand or need a fix I'm sure running a search will be of use.
Happy Day,
lak's avatar
Ag insider logo xs@2x
lak
4,555 posts
 
I failed to ask therefore I made an assumption. Is the noise coming from your speakers (as Kchahoc said ground loop) or is it coming from your amp?
awchui OP
1 posts
 
The noise is coming from the speakers. The noise was not there when I have the old set up. The noise comes on once I connect the tube amp to the preamp and turn on the amp power.
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