2. amps-preamps
  3. 184310-3592

Krell KSA 200s ground hum

I picked up this amp a week ago and I REALLY like it. When I first plugged it in with nothing attached except speakers it was silent. Like small hiss from an inch away but one of the more silent pieces I have had. As soon as I hooked up an rca from my preamp there it was. Loud ground hum. So right now I have floated the ground with cheater plugs on everything in the chain. Silence all is good with the cheater plugs and the system sounds great. If I take the cheater plug off of any of the 5 pieces in the chain it’s back! All same outlet and dedicated 10 gage line. I mean I’m “ok” with the cheater plugs if need be but…….. any ideas? 

mofojo
erik_squires
16,128 posts
 

disconnect any incoming coaxials, like cable modem, satellite TV, etc.

Also, USB cables from a PC.  :)

mofojo OP
2,301 posts
 

I can have just one of my grounded components plugged into the dedicated line with the amp. Any of them. When I hook it up via rca to the amp the hum is pretty loud. Float the ground in that component and the hum is gone. 

erik_squires
16,128 posts
 

And the amp is NOT right physically under another piece of gear?

mofojo OP
2,301 posts
 

No it’s at least 2 ft away from the closest component. 

jea48
4,450 posts
 

Are you using the OEM power cord that came with the Krell Amp?

Is there a ground loop hum with only the preamp connected to the Krell amp? (Nothing connected to any of the inputs on the preamp. No other type of ground wire(s) connected to the preamp either.

If yes there is hum with only the preamp connected to the amp, (nothing connected to any preamp inputs. No external ground wires connected to the preamp... For a test install a ground cheater on the power cord of the Krell amp only. Hum should be gone... Yes?

 

Just curious are the shorting jumpers, pins, installed on the XLR inputs?

CAUTION:Use only one input to the amplifier at a time. The KSA is shipped
with shorting pins in the XLR inputs. These pins should remain in the XLR
inputs if you are operating the KSA in the single-ended mode. When the
shorting pin is inserted, pin 1 and pin 3 are shorted together. The shorting
pins must be removed to connect the KSA for balanced operation.

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