Ground loop on speakers

[Goi]

Hi,

I just bought myself a new pair of HiVi M10 speakers, and they sound awesome. Problem is, once they're warmed up, a very audible low frequency hum(I'm assuming it's ~60Hz) is emitted. It doesn't happen when it's just switched on, at least, I don't hear it, but I hear it after a few minutes.

The volume of the hum is independent of the speaker volume knob, and even when I disconnect the audio cable from my PC, it's still there.

I'm assuming it's a ground loop. How do I get rid of it? My speakers, monitor, and PC PSU are all connected to an extension cord.

Thanks.

 

[Goi]

Anyone?

 

[Goi]

I've also noticed that the sub gets kinda hot after some time even when nothing is playing. Most sub amps are Class D, so that can't be normal right?

 

[Phynaz]

http://www.ebtechaudio.com/products.html

 

[Rubycon]

DI box or ground lift is not going to cure non ground loop related problems.
Since you're experiencing hum with nothing connected this points to a hardware defect - excessive AC ripple entering the amplifier stage. It's possible as well if the unit is insufficiently shielded, using a high gain stage and placed near a strong AC field. Try moving the speakers to another part of the room to see if the hum abates.

If not, get them swapped out.

 

[Goi]

Thanks. I'll probably get them swapped out.