Help on Aleph 5 buzz.

[protos]

My new Alephs are sounding better every day. However I have noticed that although each monoblock is very quiet by itself or connected by itself to source when I connect both mono's to source there is a perceptible buzz that is higher pitched than the very slight hum you might normally hear if you are right next to the mid /woofer.
Nelson has said that a hum is a ground loop problem and a buzz is parasitic oscillation.
How do I go about solving this problem ?

 

[wuffwaff]

Hello Protos,


sounds like a ground loop. Try disconnecting mains earth from one mono (just for testing). If this works you must change the earthing setup on your amps by inserting NTC or resistors between chassis earth and circuit earth.

william

 

[nar]

I had no buzz or hum with mine! But seems it's a ground loop...

I have no earth linked to the preamp's ground.However,each mono block is physically with its own ground,each ground goes to earth through power thermistor CL60.

The only place the 2 grounds from the amps meet is the output XLR of the preamp (there is nothing magic)

Cheers

 

[protos]

Thanks for the replies.
It seems that it is my fault for not putting in a thermistor in the connection to ground. In fact I have not put one on the power line either because my amps seemed to switch on perfectly well without it. I guess my inexperience is to blame. I did try lifting the ground on one of the monos and the buzz disappeared so I guess with the thermistors the problem will be solved.