ye olde synthesisers of yore used a DC analogue voltage as a control mechanism, this is a simple document for my own considerations.
there are 3 basic variations of "sequence" voltage sent
- CONTROL VOLTAGE, sends variable voltages, used for wide ranging parameters such as pitch (or really anything with a patch point).
In regards to pitch there are different systems, however 2 major protocols have emerged [Volts per octave, Volts per hertz].
The voltages used varies per manufacturer/device. (with voltage range being related to the octave range of the device)
CV range examples (to demonstrate possible voltage range)
Volt/oct. the voltage range demonstrates the octave range, eg 0V to 7V (7 octave range) and +/- 2V for pitch bend (2 octaves)
Hz/Volt. 0.0625V to approx 13V, (7.5 octaves)
- GATE, basically sends 2 opposing states, off/on (eg 0V - 5V).
These generally either open the VCA to allow signal through, or trigger an Envelope tied to the VCA
CV/ Gate are sufficient to send simple melodic info.
- TRIGGER, can be used to trigger notes or as a clock controller, it is a simple pulse (similar to a gate but with a set duration).
The Clock Trigger is a regular pattern of voltage pulses (generally 5V) signifiying timing steps. eg 24 pulses per quarter note (PPQN).
There are multiple variations of PPQN speed.
Roland DIN sync (SYNC24) is a regular pulse at 24ppqn, Korg uses 48ppqn.
Clock systems with a simple pulse use Tip Sleeve cables, others use Tip Ring Sleeve allowing a 0V=stop and 5V=start signal.
Other iterations of this format offer reset and fill in triggers.
Note triggers are single events that can be used to trigger drum sounds, they can also be used as a step cycle for sequencers or arpeggiators (eg. a tom output from a TR-606 into the clock input for a SH-101)
for note triggers;
V-trig is basically Gate.
S-trig shorts the signal path and is not common.
Useful Device Information
Akai MAX49
CV - 0V to 5V (1V/octave)
GATE - ??
Arturia Beatstep Pro
CV. either
1 V/Oct (0V-10V corresponds to Midi note 0-127)
Behringer Neutron
CV - 1v/octave
Behringer TD-3
Sync in - More than 2.5v
CV out - 1V to 5V
Gate out - 0V to 12V
Korg Monotribe
is switchable between either Oct/V or Hz/v, also between active high/low for Gate.
CV must be limited to 5V and gate to 20V
KORG Volca Beat
SYNC IN - max 20V
SYNC OUT jack sends a 5V pulse of 15 ms at the beginning of each step.
