[jamesf2]

Hi all

I hope this is the right section to post this in. Apologies if it is in the wrong place.

I have a rather basic system used to play music from a PC into separate rooms. The set up is as follows:

PC - Cable with 3.5mm jack on the PC end and 2x RCA on the amp end - 2x RCA to XLR adaptors - Amp (2 channels) - cables - speakers.

There is a constant buzzing from the speakers which momentarily gets louder every 15 seconds or so, just for about half a second before returning to normal.

With the input cable disconnected from the amp, there is no buzzing at all.

With the input cable disconnected from the PC but still connected to the amp, there is still a buzzing, though it is quieter.

With the input cable connected to a phone instead of the PC, there is no buzzing.

With the PC end of the cable shorted, there is no buzzing on the channel that is being shorted.

I've tried to eliminate electrical interference problems by disconnecting everything from the PC other than the power cable and cable to the amp. I've unplugged everything else from the sockets and even turned off power to all the other circuits (lights etc). The buzzing is still there.

Would anybody be able to suggest any possible solutions / things to try?

Thank you in advance.

 

[rdgrimes]

Replace the cable that connects PC to amp. Get rid of the XLR adapters and go with plain RCA connects. Either of those 2 things might solve this.

 

[Knucklehead90]

Ground loop? Do you know what a 60 cycle ground loop sounds like?

 

[GreySkies]

XLR inputs on the amp—balanced inputs? While you can connect unbalanced and balanced gear, in my experience, some brands don't like it, for example Behringer. If the amp has unbalanced inputs, try using those instead of the XLRs.

 

[jamesf2]

The amp only has the 2 XLR inputs. No RCA or anything else.

I did have look into ground loop, but the noise is still there when disconnected from all other equipment, just the input cable, amp and speakers are connected. The only thing with a mains connection is the amp itself.

 

[gregcss]

I had buzzing issue too that is likely caused by the electric wiring of the house. I fixed it with Jensen isolation transformers. Not cheap but it worked (for me).

http://www.jensen-transformers.com/home-theater/audiophile/