Why is A400 picking up interference when Rotel did not?

I cant quite understand this.

I have the A400 set up in exactly the same place using exactly the same cable as what was used on the Rotel, and yet this thing seems *extremely* sensitive to picking up interference from the PC, whereas on the Rotel, it was very silent.

Also the A400 seems to have a low level hum even when the computer is not even turned on.... although I've read that could be the caps.

Any ideas about the interference? Its the first amp I've ever had thats suffered from this problem.

 

Could it be an earthing problem causing the low level hum? Can you hear the hum when it is turned on but the volume is turned right down?

 

Yep... its always had that hum. Its mainly the interference I cant quite understand. I've moved it further away from the PC and everything, nowt seems to work.

 

Could be the internal wires acting as antennas perhaps - picking up RF from the PC? My memory's hazy on this, but maybe ferrite beads in places internally could help - or a little capacitor to filter off the stuff. A net serach or one of the forum's more technical bods should be able to help For example, a search for amplifier RFI found http://www.catchnet.com.au/~rjandusimports/rfi.html which seems to be exactly what you need

 

Thanks SteveC,

I've got an idea that will definitely help: Get my old amp back

 

When linking with my PC i had a ground loop problem.
If the hum is there when the pc is turned off but the cable connected and dissapears when the cable is dissconected then it is likely to be a ground-loop problem.

If that is the case message me and i will explain how to fix it,

 

Wise option...