Doepfer

Thanks a lot Dieter, I mentioned the LC6 for mistake in the object line, it simply is the LC3. I doubt that the problem source is the A-138s mixer, though its signal can be heard on the multed outs of the WMD buffered multiple. As soon as I come back in town, the first trial will be simply displacing the WMD multiple onto another (grounded!) case where one of the 2 audio sources comes from (an A100P9 which I assume is grounded).

Then I will try the experiment you suggest, though I never managed things like this and I just know what is grounding theoretically…

I have to specify that all instruments (except monitors and stereo amplifier) are supplied via an APC unit throughout various multiple sockets bays (instruments are connected to the multiple bays and the bays are connected to the APC unit.

Other hardware included in the patch is: A-100P9 PSU3 (DPO installed onto it) and SOFTPOP

If I properly understand, the A-100P9 should be grounded yet; as for the latter, it is not clear to me if grounded or not. Reading the manual I deduce that “yes” it is grounded, though it is not clear to me what GND means when the unit works on battery (as it can be used with 1,5V batteries as well). The manual section dedicated to the patchbay talks about grounding:



I power the unit with a universal PSU and I assume that it can assure grounding, as the SoftPop comes without any PSU… (the polarity demanded is NEG outside). So, if the universal PSU assures grounding then I probably can use this R socket to connect temporarily the LC3 case’s ground… (?)

Best wishes, 
Diego


> Il giorno 13 giu 2018, alle ore 09:53, yahoo@doepfer.de [Doepfer_a100] <Doepfer_a100@yahoogroups.com> ha scritto:
> 
> 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> [mailto:Doepfer_a100@yahoogroups.com <mailto:Doepfer_a100@yahoogroups.com>]
>> Gesendet: Dienstag, 12. Juni 2018 19:43
>> An: Doepfer_a100@yahoogroups.com <mailto:Doepfer_a100@yahoogroups.com>
>> Betreff: Re: [Doepfer_a100] 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@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
>>>>>> 
>>>>>> 
>>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> ------------------------------------
>>>>> 
>>>>> ------------------------------------
>>>>> 
>>>>> 
>>>>> ------------------------------------
>>>>> 
>>>>> Yahoo Groups Links
>>>>> 
>>>>> 
>>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>> 
>>> 
>>> 
>>> ------------------------------------
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>>> 
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>>> 
>>> Yahoo Groups Links
>>> 
>>> 
>>> 
>> 
>> 
>> 
>> ------------------------------------
>> Posted by: Diego Ragnini <diegora@free.fr>
>> ------------------------------------
>> 
>> 
>> ------------------------------------
>> 
>> Yahoo Groups Links
>> 
>> 
>> 
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