[sdiy] Synthi A breakout cable

[mdimmm at hotmail.com]

>>> Hello everyone,
>> 
>> Hi!
>> 
>>> I'm looking for some technical advice for a simple DIY conversion.
>>> I would like to make a breakout cable to connect my Synthi A to my Doepfer
>>> A-100 system, and I'm not sure whether to use resistors in the cables or
>>> not. Synthi modules connect to each other via 2.7kOhm resistors, and Doepfer
>>> modules don't, they're simple patch cables. The breakout cable would connect
>>> to the 32-way Prestopatch socket on the Synthi, with the possibility of 16
>>> inputs and 16 outputs going into the Doepfer system.
>>> To keep the signals on suitable level for both machines, should I put
>>> resistors in the inputs, outputs, all 32 cables or use none at all?
>> 
>> There is a few things to recall. In the Synthi A you have 0.33V/Oct on the
>> VCOs
>> and 0.27V/Oct for the filter (if I recall things correctly), which may or may
>> not be an issue for you. Simple voltage dividers will serve you well for the
>> scaling.
>> 
>> As for the resistors, they reside in the pins, and there exist different pins
>> depending on the strength you want. Thus, the feeding of signals into the
>> inputs is up for a suitable series-resistor. You may want to consider to have
>> a few CV-mixers for some popular CVs (like frequency controls) so that you
>> can
>> mix a few signals together prior to tossing them down the line to the
>> Synthi-A.
>> 
>> I would consider buffering, just to keep things properly isolated. The Synthi
>> A
>> matrix is sensitive as it is.
>> 
>> Cheers,
>> Magnus
>> 
> Also remember the Synthi is conceptually different than the Doepfer in that
> the outputs of modules have level controls and the inputs are "wide open".
> The reverse is true for the Doepfer. You will probably need to put level
> controls on the lines leading to the inputs of the Synthi modules. Also
> don't be fooled into thinking the 32 pins on the presto-patch relate exactly
> to the 16x16 matrix. Some of the lines are different on the presto patch. It
> has been a long time since I owned one, but I remember they are different at
> the meter and input columns.
> -James
> 
Level controls could be the same resistors as the ones used in standard
Synthi A patch pins?

As far as I know, the Prestopatch layout is identical to the matrix layout.
On the Prestopatch, the first connector on the left is the output channel #1
output, and the last one on the right is the output channel level control #2
input.

Mdimm