[sdiy] Synthi A breakout cable

[James Husted]

On 11/4/02 5:22 PM, "Magnus Danielson" <cfmd at swipnet.se> wrote:

> From: "m d" <mdimmm at hotmail.com>
> Subject: [sdiy] Synthi A breakout cable
> Date: Mon, 04 Nov 2002 23:08:04 +0000
> 
>> 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