It's not for sure that this is the reason for your problems. So I'd
recommend just to try it out, i.e. connect the GND of the A-100LC3
temporarily (e.g. the GND blade terminal on the A-100 bus board) to GND of
the other devices included in the signal path. If you use an A-100LC6
(mentioned in the subject of your message) that not necessary as the
A-100LC6 GND is connected to mains earth/GND.

Does the problem also occur if you use the A-138s outputs directly (without
the buffered multiple)

Best wishes
Dieter Doepfer

> -----Ursprüngliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com [mailto: Doepfer_a100@yahoogroups.com ]
> Gesendet: Dienstag, 12. Juni 2018 19:43
> An: Doepfer_a100@yahoogroups.com
> Betreff: Re: 1 Interferences from A-138s into LC6
>
>
> Ok thanks, so I have to learn how to ground it !
> It seems obvious but not
> I will try
>
> Floating GND ( ) needs to be deepened
> Or I’d better search for someone who can do it
>
>
> > Il giorno 12 giu 2018, alle ore 15:57, yahoo@...
> 1 < Doepfer_a100@yahoogroups.com > ha scritto:
> >
> > I fully agree. As the A-100LC3 also uses an external power
> supply it's GND
> > is not connected to mains earth/GND and has the mentioned
> "floating GND" (in
> > contrast to all other A-100 cases).
> >
> > Best wishes
> > Dieter Doepfer
> >
> >> Definitely get that case properly earthed first. Even if its not
> >> causing this issue, its not safe for you or your equipment. There
> >> should be a both crimped and soldered lug on the metal case, held
> >> in good contact with a screw and washers which connects to earth.
> >> This probably can be done by connecting the PSU ground to the
> >> case, but its worth checking that the case actually is
> >> electrically connected to the ground pin on your wall socket.
> >> Some PSUs with external bricks have a floating ground
> >>
> >>
> >> On 12 Jun 2018, at 14:20, Diego Ragnini diegora@...
> >> 1 <Doepfer_a100@yahoogroups..com> wrote:
> >>
> >>
> >>
> >> Thanks, the cables are all recent doepfer
> >> Not sure to know how to do this experiment though I will try.
> >> Which GND do you refer to
> >> Just the one of the audio 2 (the source which feeds the A138s) or
> >> the multed audio 1 as well
> >> Audio 2 is from a DPO mounted on a A-100P9 PSU3
> >> Audio 1 is from a Bastl Instruments SoftPop, which in the
> >> meanwhile went back to the dealer to be replaced for another kind
> >> of issue. I had noticed some electricity at fingers while
> >> touching the side panels of its case. It probably is not properly
> >> grounded, though it shows some sockets for grounding...
> >>
> >> Best wishes,
> >> Diego
> >>
> >>> Il giorno 12 giu 2018, alle ore 14:54, yahoo@...
> >> 1 < Doepfer_a100@yahoogroups.com > ha scritto:
> >>>
> >>> As external audio signals are involved it maybe a grounding
> >> problem. Make
> >>> sure that the cables that are used to connect the modules to
> >> the external
> >>> signals carry GND (there are patch cables available without
> >> GND, as long as
> >>> one patches within the case no problems occur, but with
> >> external signals the
> >>> GND is missing). And I don't know if all WMD sockets are
> >> grounded. In some
> >>> modules (yes, also in some older A-100 modules :-) the GND of
> >> some sockets
> >>> is not connected as it does not matter if all modules are
> >> connected to the
> >>> same GND.
> >>> You may try also the following: connect the GND of the A-100LC3
> >> temporarily
> >>> to the GND of the signal source unit (at the A-100LC3 there
> should be an
> >>> unused GND terminal on the bus board). If then the problem
> >> disappears it's a
> >>> grounding issue.
> >>> It's just an idea. Not sure if this is the reason.
> >>>
> >>> Best wishes
> >>> Dieter Doepfer
> >>>
> >>>
> >>>> -----Ursprüngliche Nachricht-----
> >>>> Von: Doepfer_a100@yahoogroups.com
> >> 1
> >>>> Gesendet: Dienstag, 12. Juni 2018 14:06
> >>>> An: Doepfer_a100@yahoogroups.com
> >>>> Betreff: Re: 1 Interferences from A-138s into LC6
> >>>>
> >>>>
> >>>>
> >>>>
> >>>> Hi thanks everybody for replying
> >>>> The situation was vague indeed, sorry, though the patch is very basic
> >>>> The case is just 1 row (LC3)
> >>>> As you can see by the colours on the following screenshot, the
> >>>> multed audio 1 signal (red cable) is slightly affected by the
> >>>> audio 2 signal (blue cable), as we turn CW the A-138s channel
> >> volume knob.
> >>>>
> >>>>
> >>>> Nothing else is patched/ engaged.
> >>>>
> >>>>
> >>>> I unfortunately have no means nor expertise for measuring anything...
> >>>> ASAP I will first try installing the multiple on another case.
> >>>>
> >>>>
> >>>> Best, Diego
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>> Il giorno 12 giu 2018, alle ore 10:25, John Hollis
> >>>> john@... 1 < Doepfer_a100@yahoogroups.com >
> >>>> ha scritto:
> >>>>
> >>>>
> >>>> Hi Diego,
> >>>>
> >>>> It does sound like there might be a short between the adjacent
> >>>> modules. Can you check for that
> >>>>
> >>>> Thanks
> >>>> John
> >>>>
> >>>>> On 12 Jun 2018, at 08:57, yahoo@... 1
> >>>> < Doepfer_a100@yahoogroups.com > wrote:
> >>>>>
> >>>>> Hello,
> >>>>>
> >>>>> the A-138s is a very simple module (just a standard mixer
> circuit with
> >>>>> operational amplifiers) and I have no idea how the signal could
> >>>> crosstalk to
> >>>>> any other module.
> >>>>>
> >>>>> Best wishes
> >>>>> Dieter Doepfer
> >>>>>
> >>>>>> -----Ursprungliche Nachricht-----
> >>>>>> Von: Doepfer_a100@yahoogroups.com
> >>> [mailto: Doepfer_a100@yahoogroups.com ]
> >>>>> Gesendet: Montag, 11. Juni 2018 15:09
> >>>>> An: Doepfer_a100@yahoogroups.com
> >>>>> Betreff: 1 Interferences from A-138s into LC6
> >>>>>
> >>>>>
> >>>>> Hello, I have a WMD buffered multiple which suffers from A-138s
> >>>>> mixer interferences, both powered by an LC6 Doepfer case. Is the
> >>>>> WMD faulty or its cable A-138s output can be heard on the WMD,
> >>>>> unless knob's fully CCW. I also see that the multed signal is
> >>>>> louder that the original one. Any hint is welcome.
> >>>>>
> >>>>> Best regards,
> >>>>> Diego
> >>>>
> >>>>
> >>>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> ------------------------------------
> >>>
> >>> ------------------------------------
> >>>
> >>>
> >>> ------------------------------------
> >>>
> >>> Yahoo Groups Links
> >>>
> >>>
> >>>
> >>
> >>
> >>
> >>
> >>
> >>
> >
> >
> >
> > ------------------------------------
> >
> > ------------------------------------
> >
> >
> > ------------------------------------
> >
> > Yahoo Groups Links
> >
> >
> >
>
>
>
> ------------------------------------
> Posted by: Diego Ragnini < diegora@... >
> ------------------------------------
>
>
> ------------------------------------
>
> Yahoo Groups Links
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>
>