CoVariant is an audio unit that turns a DC-coupled audio interface into a MIDI to CV converter. The audio unit converts MIDI note and controller data from the host app to control voltages that can be used to control external analog synthesizers, modular systems or other CV controlled analog equipment.
A single instance of the Audio Unit provides outputs for CV/Gate, two MIDI controllers and two ADSR-type envelope generators. It supports last, low and high note priorities, multiple or single trigger modes, legato or continuous glide/portamento with constant rate or constant time modes and pitch bend. The controller outputs can be set to note velocity, aftertouch or any MIDI continuous controller number (0 to 127). Controller outputs are smoothed to prevent any stepping.
Why use CV/Gate instead of MIDI?
Timing: it’s sample accurate across all the channels. No MIDI jitter or congestion issues.
Tuning accuracy: the built-in tuning process is quick and accurate and exactly matches the control voltages to the synthesizer; you don’t even need to tune the oscillators.
Flexibility: you can use the outputs of the audio interface for CV/Gate (note pitch and duration), MIDI controllers (such as note velocity, aftertouch or modulation) or software generated envelopes. You can drive synthesizers that conform to the Volts/Octave or Hertz/Volt standard, V-Trigger or S-Trigger.
Compatibility with host applications:
CoVariant requires an Audio Unit host that supports multi-channel audio interfaces. Please note that GarageBand lacks this ability and so is not suitable.
The audio unit can be installed as either a Music Effect or an Instrument. Multiple instances can be used simultaneously.
If the host application is able to support multiple output busses from an AU then a single instance can provide six outputs: CV/Gate, two MIDI controllers and two envelope generators. For hosts that only support a single stereo output from an AU it’s possible to choose between CV/Gate, two MIDI controllers or two envelope generators; multiple instances of the AU can be set to produce different outputs from the same MIDI data allowing for the same result as running a single instance in a host that supports multiple output busses.
If the host application allows MIDI data to be sent to a Music Effect, or provides sidechaining for an Instrument, then a single instance of the AU can be used to calibrate the synthesizer and generate the CV/Gate output. If the host doesn’t provide either of these features then two instances of the AU can be used instead: one installed as an effect to perform the tuning, and a second installed as an instrument to convert MIDI data to CV/Gate voltages.
Fixes a bug that would introduce a delay in the gate when using multiple trigger mode.
With Family Sharing set up, up to six family members can use this app.