Hi,

After many Google searches and advice from friends playing in bands and a studio technician, I purchased the Proel DBA1 Active DI box.
In case one encounters similar problems, this works like a charm!

Regards,

Ton

--- In Doepfer_a100@yahoogroups.com , "Ton Akveld" <aca@...> wrote:
>
> Hi all,
>
> I wonder if anyone else is experiencing hum problems like described in this thread:
>
> http://launch.groups.yahoo.com/group/Doepfer_a100/message/20598 threaded=1
>
> I myself am constructing a A-100 system and recently reached the state were it can produce a sound, a MIDI2CV interface, one VCO and a VCA, as can be seen here: http://groups.yahoo.com/group/Doepfer_a100/photos/album/1838015066/pic/444387654/view picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc
>
> The bus boards use the same power source but are not (yet) connected, hence the cable between the MIDI2CV interface and the VCO.
>
> The power source is the one coming with the DIY kit #1 from Doepfer, suppling the AC current without a ground wire.
>
> When I connect the VCA output to my Roland KC-110 amplifier, using a stereo mini-jack VCA out to the L/R Roland in channel, it starts to hum. The hum worsens when powering up the A-100.
>
> I think I have to create some common power ground, as described by Florian Anwander in the before mentioned message:
> The Doepfer system needs no additional ground, but it definitely
> requires that all connected devices (A100 racks, external mixer,
> poweramp, effects) share one common power ground. The power connector of all A-100 racks MUST be three prong connectors and the multi power
> socket bar must use all three lines.
>
> The ground from the mains however seems not to be propagated into the A-100. The Roland has its own power supply in the form of a mains to 13 V DC adapter.
>
> How on God's green earth do I get a common power ground
>
> All help & advice is appreciated!
>
> Warm regards,
>
> Ton Akveld
>