Studio Pro: The CV Instrument

The CV Instrument plug‑in. As of version 8.1, this now includes four modulation slots, which by default are filled with two LFOs and two ADSR envelopes. You can route these to any audio output on your interface, but the outputs must be DC‑coupled.

Integrate your modular into Studio Pro using the newly updated CV Instrument.

We last explored the CV Instrument in version 7. It’s an understated plug‑in that translates MIDI notes into CV pitch and gate voltages for playing external modular and analogue gear. With some imaginative use of pitch‑bend, you could also use automation lanes to generate a continuously varying voltage for some creative modulation. In version 8.1, Fender have integrated some rather interesting modulation possibilities, which gives us an opportunity to have another look at the way the CV Instrument could bridge the gap between your DAW and your voltage‑run external gear.

But first we need to go over a couple of things to ensure we’re all on the same page.

Understanding Control Voltage

Within a DAW such as Studio Pro, we’re very used to dealing with music and control in terms of MIDI. With MIDI, you can send notes, velocity, aftertouch, pitch‑bend, modulation and control change data direct to virtual instruments or external MIDI synths and modules. Everything has a channel, you have individual controller numbers, and it’s all very ordered, intentional and specific. With control voltage, or CV, you just have a variable voltage that you use for everything.

You can interpret that voltage as notes changing the pitch on a VCO, or you can interpret it as modulation changing any parameter on any module you wish to plug it into. In terms of Studio Pro and the CV Instrument, this allows us to take MIDI notes and translate them into a voltage corresponding to pitch, and with this update, use some in‑built modulators to control external modular gear.

DC Coupling

Control voltages are identical in form to audio signals, so instead of moving between machines as data on data cables (as MIDI does), they move between machines as audio signals on audio cables. The main difference is that audio signals are oscillations we can hear; they wobble at a frequency within our audible range and push speaker cones in and out fast enough to generate sound. With CV, the movement is much slower, and often, as when you want a steady pitch, the voltage does not change at all. This can cause difficulty for some audio interfaces; since they expect frequencies in the audible range, they may have built‑in filtering to block out slow‑moving or static voltages. What we need is an audio interface that doesn’t do that.

The magic term is ‘DC coupled’, which refers to an output or input that allows for flat DC voltages. If your audio interface doesn’t have any DC‑coupled outputs, then this is not going to work. Check your documentation, as many audio interfaces often have a couple of DC‑coupled connections that you can use.

The New CV Instrument

The original CV Instrument was designed to convert MIDI notes into CV pitch and CV gate signals, and that’s what we still find in the top half of the upgraded CV Instrument. But in the bottom half we have four very exciting‑looking modulators. By default these are presented as two LFOs and two ADSR envelopes, but each slot can be either, giving you a nice amount of scope.

Before we get into the details of each modulator, we need to have a word about signal routing. The modulators are going to...