Jun 13, 2018
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 1 < 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 ]
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@doepfer.de[Doepfer_a100] < Doepfer_a100@yahoogroups.com > ha scritto:
supply it's GND
I fully agree. As the A-100LC3 also uses an external power
is not connected to mains earth/GND and has the mentioned"floating GND" (in
contrast to all other A-100 cases).should be an
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:
problem. Make
As external audio signals are involved it maybe a grounding
sure that the cables that are used to connect the modules tothe external
signals carry GND (there are patch cables available withoutGND, as long as
one patches within the case no problems occur, but withexternal signals the
GND is missing). And I don't know if all WMD sockets aregrounded. In some
modules (yes, also in some older A-100 modules :-) the GND ofsome sockets
is not connected as it does not matter if all modules areconnected to the
same GND.temporarily
You may try also the following: connect the GND of the A-100LC3
to the GND of the signal source unit (at the A-100LC3 there
circuit withunused GND terminal on the bus board). If then the problemdisappears it's a
grounding issue.[mailto:Doepfer_a100@yahoogroups..com]
It's just an idea. Not sure if this is the reason.
Best wishes
Dieter Doepfer
-----Ursprüngliche Nachricht-----
Von: Doepfer_a100@yahoogroups.com
volume knob.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
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 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@doepfer.de 1< Doepfer_a100@yahoogroups.com > wrote:
Hello,
the A-138s is a very simple module (just a standard mixer
[ mailto:Doepfer_a100@yahoogroups.com ]operational amplifiers) and I have no idea how the signal couldcrosstalk to
any other module.
Best wishes
Dieter Doepfer
-----Ursprungliche Nachricht-----
Von: 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
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Posted by: Diego Ragnini < diegora@free.fr >
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