AW: [Doepfer_a100] Interferences from A-138s into LC6

From yahoo
Sent Wed, Jun 20th 2018, 07:59

Yes, these are the correct terminals. If the GND connection really solves
the problems one has to think about a permanent solution. But I have never
heard about similar problems from other customers. And we use A-100P9
together with A-100LC3 during exhibitions or work shops and never had any
problems.

Best wishes
Dieter Doepfer


> Please can someone check that this would be the right connection
> in order to grant that the A-100LC3 “GND” is temporarily
> connected to mains earth/GND? So I would temporarily connect the
> blade terminal of the first picture to the same blade terminal
> found in the A-100P9 (2nd picture).. Then, in order to set a
> definitive connection, I would provide a mains “plug" where to
> pass uniquely cables for all floating GND's in the system towards
> the mains earth/GND pin wall socket. Would both these solutions
> be correct, please?
> Best, Diego
>
>
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> Il giorno 13 giu 2018, alle ore 09:53, xxxxx@xxxxxxx.xx
> [Doepfer_a100] <xxxxxxx_xxxx@xxxxxxxxxxx.xxx> 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: xxxxxxx_xxxx@xxxxxxxxxxx.xxx [mailto:xxxxxxx_xxxx@xxxxxxxxxxx.xxx]
> Gesendet: Dienstag, 12. Juni 2018 19:43
> An: xxxxxxx_xxxx@xxxxxxxxxxx.xxx
> 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, xxxxx@xxxxxxx.xx
>
> [Doepfer_a100] <xxxxxxx_xxxx@xxxxxxxxxxx.xxx> 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 xxxxxxx@xxxx.xx
> [Doepfer_a100] <xxxxxxx_xxxx@xxxxxxxxxxx..xxx> 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, xxxxx@xxxxxxx.xx
>
> [Doepfer_a100] <xxxxxxx_xxxx@xxxxxxxxxxx.xxx> 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: xxxxxxx_xxxx@xxxxxxxxxxx.xxx
>
> [mailto:xxxxxxx_xxxx@xxxxxxxxxxx..xxx]
>
> Gesendet: Dienstag, 12. Juni 2018 14:06
> An: xxxxxxx_xxxx@xxxxxxxxxxx.xxx
> 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
> xxxx@xxxxxx.xx.xx [Doepfer_a100] <xxxxxxx_xxxx@xxxxxxxxxxx.xxx>
> 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, xxxxx@xxxxxxx.xx [Doepfer_a100]
>
> <xxxxxxx_xxxx@xxxxxxxxxxx.xxx> 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: xxxxxxx_xxxx@xxxxxxxxxxx.xxx
>
> [mailto:xxxxxxx_xxxx@xxxxxxxxxxx.xxx]
>
> Gesendet: Montag, 11. Juni 2018 15:09
> An: xxxxxxx_xxxx@xxxxxxxxxxx.xxx
> 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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> Posted by: Diego Ragnini <xxxxxxx@xxxx.xx>
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