2. amps-preamps
  3. 1303583728

Help with hum

I have a hum coming through both speakers. It is independent of volume control and completely stops when the preamp is disconnected. Disconnecting source from preamp has no effect. I have tried switching cables and tubes from channel to channel but it keeps humming. I have tried all combinations of cheater plugs on both amps and on the preamp but with no improvement. Any advice regarding cause or diagnosis is appreciated. Preamp is Cary SLP-98 and amps are Manley Neoclassic 300b's.

Thanks in advance,

Dave
128x128dbrewer12345
zmanastronomy's avatar
zmanastronomy
738 posts
 
Try hooking a ground wire from a screw in the back plate of the pre to a screw in the back plate of the amp.
It should help out.
dbrewer12345's avatar
dbrewer12345 OP
16 posts
 
Zman,

I tried your tip without success. I did eliminate the hum when I touched a wire grounded to the pre to the (+) speaker terminal of either amp. I realize that is not a realistic solution but may help someone offering advice.
zmanastronomy's avatar
zmanastronomy
738 posts
 
Try hooking the ground wire from the source to the amp.
tarsando
578 posts
 
Since there is a ground connection on the interconnects, I don't see how connecting a separate wire as suggested would help. Plus I personally wouldn't do it because of possible electrical consequences that I don't really understand. Better safe than sorry. Good luck finding a solution!
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