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Studio One: Controlling Your Modular With CV Instrument

PreSonus Studio One: Tips & Techniques By Robin Vincent
Published February 2025

The new CV Instrument plug‑in will take your MIDI data and output it as control voltages and gate signals through your DC‑coupled audio interface.The new CV Instrument plug‑in will take your MIDI data and output it as control voltages and gate signals through your DC‑coupled audio interface.

With the introduction of CV Instrument, you can control your modular rig from Studio One!

One of the most interesting and yet slightly under‑the‑radar new features in Studio One 7 is the CV Instrument plug‑in. It sits very unassumingly in the instrument plug‑ins list, and is easily ignored. For modular fanatics such as myself, who enjoy nothing more than complex interconnected workflows, it is a source of exciting Studio One‑to‑Eurorack action.

However, there seems to be very little information out there on how to use it. As I mentioned in my Studio One 7 review, the manual is factual rather than instructional; hopefully, I’ll be able to help with that. So, couple your DCs, grab some patch cables, plug in some mini‑jack adaptors and let’s get Studio One talking to your modular.

CV Instrument takes a regular MIDI note from your MIDI controller or sequence and converts it into a voltage to send to your VCO.

Nuts & Volts

CV Instrument is a virtual instrument plug‑in that can send note pitch and gate information out of Studio One and into your Eurorack synthesizer in a form it will understand. That form is CV, or Control Voltage. The pitch of a Voltage Controlled Oscillator (VCO) is... controlled by voltage, which means that as you change the voltage, the pitch or frequency of the oscillations changes. As standard, a change of 1V equates to an octave shift in pitch. So, CV Instrument takes a standard MIDI note from your MIDI controller or sequence and converts it into a voltage to send to your VCO. Easy, right? The process is easy enough, but the physicality can be a bit of a struggle.

CV happens along the same pathways as audio signals. You’re not sending MIDI or other digital data between machines, but varying voltage signals down jack cables. CV is the same as analogue audio, except it’s usually moving too slowly for us to hear. To get CV out of our DAW, we will need to use an audio interface — more than likely the same audio interface you’re using for audio. However, many audio interfaces have a high‑pass filter built into the signal path to remove exactly the sort of voltages we are trying to generate. This ‘AC coupling’ can have benefits for audio applications, but makes the outputs useless for CV.

Before you can send CV to your modular from CV Instrument, you need to tell it which analogue outputs on your audio interface to use.Before you can send CV to your modular from CV Instrument, you need to tell it which analogue outputs on your audio interface to use.

So the first piece of the puzzle is that your audio interface must not be AC‑coupled; it must be ‘DC‑coupled’ so that it can let slow‑moving or stable voltage signals through. We’re only going in one direction, from Studio One to our modular, so our audio interface only needs to have DC‑coupled outputs. Fortunately, this is becoming more common in modern audio interfaces. Most interfaces from PreSonus, MOTU and RME are DC‑coupled, and you should find it mentioned in the specifications of other brands and models. However, not all interfaces are the same, and you may find that some will work better than others. The Komplete Audio 6 from Native Instruments, for instance, is DC‑coupled but can only output a range of 2V, and so won’t give you more than two octaves of notes.

My audio interface is the excellent SSL 12, which has DC‑coupled outputs, but for reasons I can’t yet explain, it refused to work...

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