2. amps-preamps
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Identify this hum, please

Added a new (used) mono pair of amps which didn't hum in the system I heard it in. Previous amps haven't hummed in my system at all. It hums equally from both channels, gets louder as you turn up the volume. Tried lifting grounds with cheater plug, no change. Tried moving it to a different circuit using an extension cord and it hums and buzzes there. What could it be?
dhcod
ozzy's avatar
ozzy
7,468 posts
 
Many ground hums are caused by Cable TV. Do you have any type of cable TV connection into any of your equipment?
dhcod OP
710 posts
 
I did all the ground lifting and measuring and in the end it's not the amp. It's the preamp. I replaced the passive with an old Advent 300 receiver (using it's preamp out) and the hum is gone. That Advent actually sounds WAY better than it should. I've always been a passive guy but I've heard that my amps (Joule-Electra Stargate SET) rather like a regular preamp. After hearing even the Advent I can see why. These are great amps by the way. Any preamp suggestions :)

Thanks to everyone for their help!
atmasphere's avatar
atmasphere
11,807 posts
 
Ah. The hum was caused by noise pickup in your cables, and the impedance of the passive setup was so high it could not control it.

A tube preamp would of course be my first suggestion.
dhcod OP
710 posts
 
That's where I'm headed. Lots of money though so I'll be saving up!
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