Doepfer

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@doepfer.de [Doepfer_a100] <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@free.fr
>> [Doepfer_a100] <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@doepfer.de
>> [Doepfer_a100] <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
>> [mailto:Doepfer_a100@yahoogroups..com]
>>>> Gesendet: Dienstag, 12. Juni 2018 14:06
>>>> An: Doepfer_a100@yahoogroups.com
>>>> Betreff: Re: [Doepfer_a100] 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@hollis.co.uk [Doepfer_a100] <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@doepfer.de [Doepfer_a100]
>>>> <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: [Doepfer_a100] 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
>>>> 
>>>> 
>>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
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>> 
>> 
>> 
>> 
>> 
>> 
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