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MIDI-CV converters can have up to four different types of outputs used to control analogue synths,
usually labelled CV, GATE, S-TRIG and AUX. Below is a description of what they do:
Pitch - CV outputs (V/oct, Hz/V)
The CV (control voltage) is a voltage that tells the synth what note to play. Most synths use the 1 Volt
per Octave (V/oct) pitch scaling system to control the pitch. This means, that each octave is 1V
(V=volts) apart (or 0.0833V per semitone).
For example, bottom C (MIDI note #36) corresponds to 0 Volts. The next C will be 1V, 2V, 3V etc..
Synths using this system include Roland SH101, Sequential Circuits Pro 1, ARP Odyssey, Oberheim
OB 1.
Some other synths, most notably Korg and Yamaha, use a different pitch scaling system. This is an
exponential method called Hertz per volt (Hz/V). This means that for the next octave up, the voltage is
doubled. So bottom C (note#36) will be 0.25V, the next C will be 0.5V, 1V,2V, 4V etc.
If you are not sure which C is MIDI note #36, use MIDI analyser mode to check.
If you use a Hz/V synth with a V/oct pitch output (or vice-versa), the synth will play out of tune but will
not cause any damage to the synth.
Note - The Korg Monopoly is an exception. Although other Korg synths use Hz/V scaling, this synth
actually uses V/oct scaling.
Gate - (Or S-TRIG)
The GATE (sometimes called V-trig [voltage trigger]) signal is a voltage that tells the synth when to
play the note. The GATE voltage will usually be a positive voltage when the note is on, and 0V when
off.
Some other synths, like Moog, Korg, and Yamaha, use S-TRIG (Short Trigger) instead of GATE. This
signal still tells the note when to play, but it is a different type of signal (electrically). To tell the note to
play, the converter will provide a short circuit at it’s S-TRIG output (0V), and to turn off the note the
output will be open circuit (literally like opening and closing a switch).
A point to watch for: unless you know the synth, it will not always be clear what type of CV and GATE
signals are required to play the synth.
For instance, the Korg MS20 requires an S-TRIG signal, but the input is labelled TRIG. Another
example is the Yamaha CS5. The pitch input is marked CV, but requires a Hz/V signal. The best way
to check is either ask someone who knows, or just try all types of output till the synth works correctly. If
you do plug your synth to the wrong outputs, it shouldn’t do any harm, although always start out with
minimum voltages.
Here’s a general guide to the most common synths and how to hook them up to your converter
SYNTH MODEL
CV OR
HZ/V?
S-TRIG OR
GATE
AUXILIARY
CONNECTIONS
NOTES
MINIMOOG
CV
S-TRIG (5V)
FILTER OR
LOUDNESS
CINCH-JONES CONNECTOR NEEDED
MOOG PRODIGY
CV
S-TRIG (5V)
FILTER
KIT AVAILABLE FOR FILTER IF NOT FITTED
MOOG ROGUE
CV
GATE (5V)
KIT AVAILABLE FOR FILTER
MOOG SOURCE
CV
S-TRIG (5V)
KIT AVAILABLE FOR FITLER
ROLAND SH-101
CV
GATE (5V)
CLOCK IN (SYNC)
KIT AVAILABLE FOR FILTER/MODULATION
ROLAND MC-202
CV
GATE (5V)
KIT AVAILABLE FOR CV/GATE/FILTER/SLIDE
ROLAND TB-303
CV
GATE (5V)
FILTER (SEE RIGHT)
KIT AVAILABLE FOR CV/GATE/FILTER/SLIDE/ACCENT
SEQUENTIAL PRO-1
CV
GATE (15V)
FILTER
KORG MS-10/20
HZ/V
S-TRIG (5V)
ANY OTHER
THERE ARE MANY EXTRA INPUTS ON THE MS10/20
KORG 700S/770
HZ/V
S-TRIG (5V)
FILTER
KIT AVAILABLE FOR CV/GATE AND FILTER
KORG MONOPOLY
CV
GATE (15V)
VCF/PORTAMENTO
ARPEGGIO CAN ALSO BE CONTROLLED
YAMAHA CS-10/20/30
HZ/V
S-TRIG (5V)
FILTER AVAILABLE FOR CS-5
ARP ODYSSEY (&AXXE)
CV
GATE (15V)
KIT AVAILABLE FOR FILTER
ARP 2600
CV
GATE (15V)
FILTER
OCTAVE CAT/KITTEN
CV
GATE (15V)
FILTER
This is a general guide only, further socket kits are available, and many other synths can be controlled.
There simply is not the space to detail all connections to all synths. However if you visit our website you
will find more information there.
A further point to watch for. Some synths use stereo jacks for the CV and GATE connections. Moog,
for instance, use a stereo jack for CV In/Out, and a stereo jack for S-TRIG In/Out on some synths.
A BRIEF GUIDE TO MIDI TO CV CONVERSION FOR THE BEGINNER
