Controlling Eurorack with an Acoustic Violin

Liz Dobson | University of Huddersfield
Yorkshire Sound Women Network

This summer I was fortunate enough to receive a CTRL from Delta Sound Labs and secure a residency at Q-O2, a subsidized arts space in Brussels. This blog presents a little technical info and some findings from my CTRL experiments.

Introducing CTRL module for Eurorack

This is beta module is set up with gate (or trigger) on the left (each send has a red LED), and continuous control voltage on the right. It receives control from Max 8 via a USB. For this particular project Delta Sound Labs also sent me their [helmholtz~] object for pitch tracking an acoustic signal, and a patch that converts this signal into CV. I’ll come back to the Max patch.

I used a Meyers Feather pickup to take a signal from the violin. Max receives the violin audio and communicates with CTRL via the [serial] object.

I have modified it and will explain some of the additions; the beauty of this setup is naturally this incredible flexibility. I’m not at all experienced with Max so I’d love to see what could be done by an experienced coder.

The [helmholtz~] object receives the signal, which is sent to [env~] then to gated output. When a signal is registered the toggle shows white. I have adapted the patch so that this is triggered on/off only when receiving a particular volume level. It means that I can set different levels for different sends.

The first clip is a brief demonstration of violin pizzicato triggering this gate.

The rest of the patch corresponds to the right side of the ctrl. The bottom four sends are DAC7 through DAC4. DAC2 & 3 are sending continuous data from the envelope output. DAC4 can be used to tell a VCO to play the same frequency as the violin.


This mean that I can send the same frequency to any VCO but I need to tune them to match first.

I’m looking at different ways of controlling the oscillators from my violin. So I have split the frequency input into bands in Max:
DAC5 only send if fr value is below 380Hz (which is just below Concert A).
DAC6 only send if frequency value is above 390 Hz but below 650 Hz (which is roughly the open E on a violin).
DAC7 only send if frequency value is above 650 Hz.

This means that I can set up harmony.

I have also set this up so that I can return to sending the full frequency range to all three DACs (5-7). That happens at the end of the last example.

The patch actually toggles between these options directly from the violin. When playing the open g string (~195Hz) the patch switches back to option 1 (same frequency to all) and when playing a frequency higher than 800Hz the frequency of oscillator performance is only affected when performing within the bands set (as shown above).

I’ve set up the forth toggle to trigger Freeze on Clouds. The volume threshold is slightly higher (so I’m using this to tap the instrument to trigger Freeze) and louder still to turn it off. Apologies. It sounds like I’m damaging the instrument, I’m really not striking it as hard as it sounds! Sometimes the general volume triggers it, so that’s something I need to think about.


Then sending LFO to control freeze Blend.

Finally, I sent the same violin frequency via CV to Batumi quad LFO and a square LFO out to pitch modulate one of the VCOs. The result is a rhythm that is dependent on the pitch performed.

I am not a Max user but this project has really opened up some interesting avenues for composition and I look forward to seeing how others use ctrl with their setup. Now I’m continuing to work on the patch and create one short piece for violin and modular, still with the dream of to writing piece for string quartet and modular. Huge thanks to Delta Sound Labs and notably Ricky Graham for the equipment and support. To Owen Green for assistance with Max. To Q-O2 for facilitating and supporting the residency, and to The University of Huddersfield for supporting this creative work while on sabbatical.

Dr Liz Dobson teaches sonic art and computer composition and The University of Huddersfield. Email: Twitter: @LizDobsonUoH

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