arp trig/gate idea problem..

[Stopp,Gene]

The web site that Martin mentions has what you need (another bookmark!).

There's two ways to add external CV/Gate control to the Odyssey. One is
to interrupt the Odyssey's internal CV and gate with external jacks (if
you use switching jacks then you can have the Odyssey act normally when
nothing external is plugged in). The other is to add the external inputs
to the existing circuit, summing in the CV and OR-ing in the Gate. If
you choose the latter approach, then you will have problems with the
Odyssey detuning as the internal keyboard sample and hold circuit drifts
when no keys on the keyboard have been pressed for a long time. In a
MIDI setup this would be a pain in the ass.

When I added external jacks to my Odyssey, I used the summing approach
because I wanted to slave it to another synth yet still use both
keyboards (for an interesting transposition effect). This required an
extra dual op-amp to make a non-inverting summer, plus the external gate
OR-ed into the existing one with a diode. If I incorporate it into my
MIDI setup I'd have to add a switch or something or else I'd have to hit
a key every couple of minutes to keep it in tune (unless I want it for
non-tuned sound effects, which an Odyssey happens to be quite good
for.....)

BTW the Odyssey I modified is a white-face with a 24 dB/oct VCF from an
Omni II (it needed a filter transplant and the Omni was dead, so he gave
his guts to science).

The circuit boards in the Odyssey are connected together with a
"backplane" circuit board that is held in place by molex connectors on
each of the panel circuit boards. This "backplane" serves as the
interconnection between the circuit boards. The CV and gate outputs from
the keyboard circuit go over this backplane to the other boards. You can
intercept these signals at this point, by bending the pins out of
alignment at the molex connector and adding wires to the external jacks.

 - Gene

 ----------
From: Martin Fay
To: IXQY at aol.com; synth-diy at mailhost.bpa.nl
Subject: Re: arp trig/gate idea problem..
Date: Thursday, February 19, 1998 10:17AM

>  I have a whiteface Odyssey that I would like to add external CV and
>  Gate
> inputs to so I can control it with my recently acquired
> Expressionist. Someone told me the inputs should go to board "A" but
> I have no documentation to follow so I put this project on hold for
> now.
>  I would appreciate any info on how to go about adding these inputs
>  so I can
> control it through Midi with the rest of my setup.

Have a look at Phil Pilgrims site: http://robotnik.com/the_lab/

He has scans of the Odyssey service manual (covers all versions), and
a lot of other stuff.


Martin

Curious Yellow / 3 track demo now available on mp3
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