unusual interference on PC. Zed10fx

hi there
I have a Zed10fx that when plugged in to the same mains ring as my PC causes a whine in the DAW. This is when NOT switched on and with no USB connection. The whine reduces a little when the Zed10fx is switched on.
Has anyone else experienced this?
cheers
Simonastro

What you mean with no connection? Is it connected to the PC?
If not something is wrong with your PC…
If it is connected and just switched off, then something is wrong with your PC…

Assuming that your Zed10 is not broken,
there is a ground loop introduced that should not happen with a correct wired PC.

@simonastro

plug it into a different outlet on a different circuit

Is there any connection USB or analog between the ZED and PC when you hear
the whine?

Are there any other pieces of equipment connected to the PC?

Where do you hear the whine coming from, speakers, headphones, directly from
the PC or mixer it self?

What happens when you unplug the ZED from the power outlet?

thanks for your responses folks

@SteffenR the PC is a newly built DAW with a BeQuiet Dark horse 11 power supply and works as it should. the Zed10fx is far from new but doesn’t exhibit any faults.

@volounteer have tried that ?

@Mike C sorry yes audible through Audient id14 USB soundcard, and does not occur if the Zed10fx is unplugged.

It sounds improbable I know but these are the symptoms.

What type of connection are you using between the ZED and PC?

If it is an analog output on the PC like the headphone jack to a line input
on the ZED it is not uncommon to need transformer isolation for that kind of
computer to audio mixer connection.

@simonastro

how does the pc and the zed connect?

do you know how they are grounded internally and also wrt the power plug?
are the power cords 3 prong or polarized or can they fit in either way ?

you cant hear a sound card.
do you use the speakers or headphones or other way to hear what the soundcard signal goes to.

actually it seems quite probable but we need more details to figure out why.
there are 2-3 reasons for what you described.

did you build the pc running the DAW or was it OEM built and you bought it OTS.

how does the pc and the zed connect?

good question

@volounteer yes ? - full disclosure I built the PC, which I’m now diagnosing over the phone due to Covid.

I’ve learnt today that a yamaha desk is also provoking similar behaviour, and when either USB connection to the PC or XLR to the soundcard.

Must be the PC then. ??

thanks you all for your help

Simon