Ok - I am not sure if the schematic you linked is actually an OB-SX
board. Assuming it is, it has 2 envelope chips (the should be Curtis
chip likely a 3330) for both the VCA and the VCF. Check your board
to see if it has these chips. It has slots for all the control
voltages for ADSR shown on the left side.

I own an OBX-A and have done a lot of mods and I am sure this is a
different schematic, but I don't know if this and OBX-A or OB-SX.

If your board is the same as the schematics, you just need to provide
the static voltages to control all of the items shown on the left. I
think the voltages range from -5V to 5V in most cases, but you need
additional schematics to make sure.

Also note, the board does not have an LFO, so you will have to build
one (these are fun to make, I added a 2nd LFO to my OB-X and it was
not that hard to make.)

This is a big project, even to make a mono-synth without memory. The
good news is, if you plan ahead, you can do it without making ANY
modifications to the sound board. Nothing to loose but time and
money, and perhaps your wife if applicable.

--- In oberheim@yahoogroups.com , ogusa@... wrote:
>
> Each of the connections like PWM, ENV etc. are voltage control
inputs.
> THe voice board does not produce envelope or control voltages,
they
> were created by the CPU.
>
> You face quite a challenge YOu would have to build at leat 2
envelope
> generators and LFOs, as well as several static voltage generators
> (pots), get voltage control to the envelopes and LFOs and set up a
> routing matrix. Even on the classic monosynth, the architecture is
> "normalized" but there are switches for various CV routing otions.
>
> Plus much of the Oberheim "sound: came from the many control
> possibilities (Env mod PW 1 with delay etc). If you want that
sound,
> you are going to have to build half of a a full modular system to
> support the module.
>
> Anyway, unless you're a analog synth designer or advanced hobbyist
> (like myself), you'll never get it to do what you want.
>
> Sorry,
>
> Peter
>
> Quoting analogback <gehayman@...>:
>
> > thanks for the reply Jeffrey,
> > i found schematics and voice board connector info today,
apparently,
> > the board was from a blue obsx which is supposed to have the same
> > voice card as an ob xa. but a few questions remain!
> >
> > i have a midi-cv converter and +15v -15v & -5v power supply
(required
> > voltages)
> >
> > there are a few connector ins/outs that are labeled but not
> > immediately obvious to me so i will try to get more info!
> >
> > if anyone with knowledge of these machines would care to take a
look
> > at this picture, perhaps it could help me determine the less
obvious
> > connection points
> >
> > http://i133.photobucket.com/albums/q55/neonleg/obxapinout.jpg
> >
> > thanks!
> >
> >
> >
> >
> > --- In oberheim@yahoogroups.com , Jeffrey Nelson <nelsonj_sce@>
wrote:
> >>
> >> You will need to power it up, and then supply it with
> >> a gate and CV. A good place to start is a Midi to CV
> >> converter. You can get them off of Ebay around $75.
> >>
> >> The problem will be the power supply, you will likely
> >> need +/- 12V and +/-5V and others perhaps.
> >>
> >> The other problem is that you need to provide voltages
> >> for all of the envelopes, VCF filter and res...
> >>
> >> Finally, you need to build an final output stage for
> >> overall volume control.
> >>
> >> In short, it can be done, but it won't be easy. Not a
> >> simple project. Get a schematic first. Good luck.
> >>
> >>
> >> --- analogback <gehayman@> wrote:
> >>
> >> > hello! i have an obsx voice board that i would like
> >> > to try and modify
> >> > in order to use it as a standalone monosynth.. does
> >> > anyone know if
> >> > this has been done before if its possible
> >> > obviously the boards
> >> > connector info would be a great help as well!
> >> > any info appreciated as i've scoured the net to no
> >> > avail :(
> >> > greetz
> >> >
> >> >
> >>
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
>