My Sick Plans For Two SEM's

From us008586
Sent Fri, Sep 8th 1995, 03:24

I recently got two brand new Oberheim SEM's as PART of a deal I did with
a guy for one of my MemoryMoog's.  Let me tell you, these babies look 
like they were just built yesterday.  Evidently, they were found in the
back of some service center that probably ordered them as replacements
for a 2/4/8 Voice an just simply never used them.  The slight downfall to
my units are that they are just the front panel and the circuit board.
No power supply or case.  With this in mind, I am getting ready to make
a fully patchable 2-Voice Modular.

The following is what I've planned out...if anyone notices any big oversights
please let me know before I start cutting metal.  To house the units, I've
purchased a BUD 8 space (14") steel rackmount enclosure (black finish with
rack rails on the front and back).  As you might expect I will be mounting the
SEM's on the upper part of a 8 space blank rack panel.  Below each SEM will be
thirty-six 1/4" jacks with the following connections:

VCO 1 - CV In #1
VCO 1 - CV In #2
VCO 1 - Modulation In
VCO 1 - Sync In
VCO 1 - Sync Out
VCO 1 - Sawtooth Out
VCO 1 - Pulse Out

VCO 2 - CV In #1
VCO 2 - CV In #2
VCO 2 - Modulation In
VCO 2 - Sync In
VCO 2 - Sync Out
VCO 2 - Sawtooth Out
VCO 2 - Pulse Out

VCF - Audio In #1
VCF - Audio In #2
VCF - CV In #1
VCF - CV In #2
VCF - Modulation In
VCF - LPF Out
VCF - HPF Out
VCF - Bandpass Out
VCF - Selected Filter Output

ENV 1 - Gate In
ENV 1 - Trigger In
ENV 1 - Normal Output
ENV 1 - Inverted Output
(This will be the Normal Output sent through a basic
op-amp inverter circuit)

ENV 2 - Gate In
ENV 2 - Trigger In
ENV 2 - Normal Output
ENV 2 - Inverted Output
(This will be the Normal Output sent through a basic
op-amp inverter circuit)

LFO - Trigger In
LFO - Output

VCA - Audio In
VCA - CV In
VCA - Output

Add 'em up...that's 36.  As you can see we're talking some
serious power and flexibility here.  For longevity, all the jacks
will be insulated/enclosed Switchcrafts.  In addition, I plan
on adding a toggle switche that will let you select how
the envelopes are triggered (+Gate or +Gate/Trigger), another
to determine whether both envelopes are driven by a common trigger,
and finally a switch to determine if both VCO's are driven with the
same CV.

BTW, does anyone know which VCO's CV is used when the two VCO's are
linked????  Also, which trigger is used when both Envelope Generators
are linked by common triggers????

All the jacks will be connected to the SEM boards via the already
installed Molex receptacles.  In case your unaware, the mating plugs
are readily available from Digi-Key.  The following are their 
part numbers:

3 Circuit Molex Plug w/o Mounting Ears -> WM1221-ND ($3.70/10)
4 Circuit Molex Plug w/o Mounting Ears -> WM1222-ND ($5.32/10)
0.062 Male Crimp Terminal              -> WM1000-ND ($10.50/100)
 
For the needed +/- 18.5VDC, I am going with a Power-One Linear, Adjustable
Dual Output power supply.  The model I am using is adjustable from 18-20
volts on each output and is rated at 0.9 amps per output.  Should do the
job nicely!

I'm sure I am going to have a fun time drilling all those 1/4" jack holes
and routing out the large openings for each SEM.  But when I'm finished, I
should have a top-notch modular to complement my Roland System 100m setup.

Jeff