Doepfer

> -----Ursprüngliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com
> [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von palicki
> Gesendet: Samstag, 22. August 2009 14:21
> An: Doepfer_a100@yahoogroups.com
> Betreff: [Doepfer_a100] Precision adder/Sequential switch/Sequencer
> question
>
>
> Hi all,
>
> Here comes a question regarding a strange muting behaviour of my
> A-151 Sequential switch.
>
> I have a Precision adder (A-185-2), a Sequential switch (A-151)
> and two A-110's set up in the top row of an 9HE low cost case.
>
> The CV output of one row of an MAQ 16/3 sequencer is connected to
> one of the inputs of the Precision adder (switch in "+" mode").
> CV values from the MAQ are the distributed by the A-185-2 to both
> oscillators through the system bus.
>
> I would then like to offset the sequence from the MAQ by using
> the Sequential switch and connect it into another of the Precison
> adders inputs.
>
> But when I connect the O/I of the Sequential switch into another
> input of the Precision adder (switch in "+" mode"), and when
> there is no input to the Sequential switch (nothing plugged in
> into I/O 1 through 4), the oscillators go mute! The sound
> disappears completely.
>
> No CV -> A-151 -> A-185-2 -> System bus = mutes A-110 = no sound!
>
> Could someone explain what is going on?
>
> Thanks,
> Jacob

The inputs of the A-185-2 are very high impedance inputs to avoid any load
of the CV connected to it. If you insert a patch cable with an open end into
one of the A-185-2 inputs the input in question does not "know" which
voltage is applied and will generate a random voltage (usually very high or
low, i.e. ~ +12V or -12V). If the output of the A-185-2 is connected to a
VCO the frequency will go ~ 12 octaves up (or down) and it seems that the
VCO does no longer generate a signal.

The same happens when you connect an input of the A-185-2 to an A-151 socket
that is not addressed.

Remark: an open input is not the same as a grounded input (0 V) !

Best wishes
Dieter Doepfer