Buzzzz!

[Huge]

Thanks, I knew I meant to try that!

Which they are.

Quite. Might have a poke round inside the PC.

[Huge]

Yeah, I know. And when new, which this one is.

Already have.

:o(

[John Rumm]

I would suggest a different lead as a good starter. (Possibly a bit of contact cleaner sprayed on to plug prior to insertion and give it a twist).

[Dave W]

"The PC is protected by a UPS"? So it's not running directly off the mains? Then surely the UPS is the prime suspect? Something wrong with the earthing circuit?

[Brian Gaff]

Maybe but it was not buzzing before he says. Its a pity it was not a laptop.

My feeling on this is that the power supply in the pc has an issue somewhere now, probably caused by the load switching. Hopefully its not the motherboard sound system but one could plug in a USB sound system and see if that buzzes as well I suppose. I'd ALWAYS, unplug a pc when nyone is fiddling with the mains as even when they are off, they are normally on as far as the psu is concerned to supply current to the usbs for charging stuff. Brian

[Brian Gaff]

Most amps these days do not have earths in any case. It has to be something very local. The only other thing is the socket itself, but normally if those jacks are dodgy its cracklying and out of phase, not hummy.

The ultimate test i suppose is a mains supply from another house. if it buzzes on the phones its not the amp after all. Brian

[Brian Gaff]

Not convinced. Unfortunately UPs devices tend to be just powering it part of the time. Unless there is aomethingextremely strange, the earthing should not in fact matter. The fact that its mains hum, not that orrid spiiky buz one gets from the cheap ups devices would still tell me something going on in the pc. Easy enough to check of course take the ups off and use it naked so to speak. Brian

[Adrian Caspersz]

Might not be the PC, but rather a fault in the UPS?

[Huge]

OK, I freely admit it. I am a knob. An eejit.

Something in the pile of crap on my desk had sat on the remote control for the amplifier and turned it up full (2 x 75W). That's why I thought altering the volume (using the remote) made no difference to the hum, 'cos it was already as loud as it would go. Turning the amp down to a sane level makes the hum go away.

Sigh.

And thank you very much to everyone who responded.

[rick]

In a previous life .. often used to find a loud buzz on audio would change in volume when you touched the tone arm or metal faceplate of an amp. Usually caused by poor earth connection.

It could be just that PC mains lead or the USB lead to speakers (if plugged in by USB that is) are picking up induced noise .... try moving it's route.

I have a speaker phone that buzzes whenever I have desk lamp in use ... no fault - just induced noise.

[Huge]

Naah, it was user error. But thanks for the reply.

[Andrew]

+1

[Andrew]

Or even £11,995 ...

[burns.me.uk]

I know Huge found the cause of his buzzz ...

I recently added a reasonable set of amplified 2.1 speakers and changed the KVM in my study, then started to notice annoying thrips and clicks on the audio, which I initially thought were from the KVM, but bypassing it proved they weren't, and they were present from the heaphone socket of the laptop itself, and on the docking station.

The monitor is connected by miniDP and has another headphone output, tried that one and it's free from the stray noises, however when the screen blank ing kicks in, the audio goes off too.

So I treated myself to a dirt cheap DAC

Metal case, USB powered, outputs to coax S/PDIF, TosLink S/PDIF, headphone and phono, USB powered, no extra drivers required, I won't bang on about ho w rounded the bass and crisp the treble it gives, or how I can hear the dif ference between a poundland USB cable and a Russ Andrews one, but it certai nly is the best PC audio I've ever had ...