You could try using an isolating USB.


Best Regards
Laurie Biddulph
Mobile: 0400 257 645
Phone: +61 (0)2 4340 0938
Web: www.elby-designs.com
Skype: widgetoz

Elby Designs
9 Follan Close
Kariong
NSW 2250
Australia


-----Original Message-----
From: Doepfer_a100@yahoogroups.com [mailto: Doepfer_a100@yahoogroups.com ] On
Behalf Of codotinc
Sent: Saturday, June 01, 2013 6:41 AM
To: Doepfer_a100@yahoogroups.com
Subject: 1 Re: Doepfer 6U Suitcase making sounds

Hi Dieter and Florian --

Thanks for your replies.

Florian: you were right in your diagnosis -- it was my USB-powered audio
interface. The synth was totally quiet until I plugged it into the
interface.

So, that's sorted but it's a bit of a pain! Now I need to get a new audio
interface !

Thanks for your help -- glad to know that my PSU is not stuffed.

Kind regards,
Jon

--- In Doepfer_a100@yahoogroups.com , Florian Anwander <fanwander@...> wrote:
>
> Hello
>
> to both Nathan and Jon: is this a mechanical sound or does it come
> from the speakers
>
> If it comes from the speakers, disconnect the audio out from the A100
> system, and connect a headphone with a mini jack connector to the
> output of the last module in the audio chain (example: VCA or mixer)
> and turn it up. Do you still hear the noise
>
> If yes, then the problem is in the A100
>
> If no, then the problem is in the combination of the A100 with the
> rest of your system
>
>
> To Jon:
> Do you use an computer with and USB Audio interface
> If yes: Is the interface USB-powered
> If yes: use an interface with an separate power supply.
>
> USB-power on Audiointerfaces in a studio like environment introduces
> HF from the digital signals of the computer in the audio ground. Those
> are useful only for standalone usage.
>
>
> Florian
>




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