How can your DAW communicate with Eurorack?
One of the driving forces behind modular and Eurorack synthesis is the desire to spill back out of the box. There’s a sense that even though computers are astonishingly capable, we can enjoy a more natural connection to our music and our creativity when handling hardware instruments. For some, this has meant moving on from using a computer and a DAW entirely. However, for most of us, it means that our creative space is quickly becoming a hybrid of software and hardware raising the question, “how do we connect these two worlds?” It’s a particularly interesting question when talking about modular synthesis because the language of control and musical expression is spoken through control voltage (CV) rather than the more familiar and computer-friendly MIDI.
In this article, I’m going to talk about three ways in which your Eurorack or modular synthesizer can connect into your digital workflow to either remind you of the usefulness of your DAW or to show you how you can spill out of your own box with the minimum of fuss and bother.
Before we talk about communication, sequencing and creative couplings there’s a more basic use of the computer that’s enormously helpful to modular synthesizers. And that’s to use it as a good old-fashioned audio recorder. Yes, that’s right, even huge modular setups that do everything live need to send their sound to somewhere so that it can be mixed down to some sort of format for delivery to your chosen medium.
The simplest version of this is to record the stereo output into your computer via a simple audio interface. You can use whatever recording software you like, but this is most likely going to be your DAW. At this stage you don’t need to be concerned about synchronization, tempo or locking anything to a timeline, your DAW is acting simply as a recorder.
If you want to keep your options a bit more fluid then you could route multiple channels out of your modular and into a multi-channel audio interface and record into your DAW onto separate tracks. You could take different oscillators to different tracks, drum sounds, noises and percussion to other tracks. This gives you the opportunity to mix and balance the sounds better. You can also add some effects processing, fade tracks in and out, make use of panning and dynamic processing.
Instead of recording a single performance out of your modular you could layer sounds up by recording one thing at a time into your DAW. Then during playback, you could work up something to go along with that and record it alongside. This means you could build up a huge piece of music with a small modular setup. It does start to bring up issues of synchronization. If you are using different arpeggiated or sequenced hardware, how does that sync up to the track you’ve already recorded? Good question. You can “wing it” and call the resultant mess “character” and “quirkiness” but perhaps it would be better to look at the next option.
Typically speaking, DAWs and computers prefer MIDI. It’s a language they understand and are designed to work with. Fortunately, there are Eurorack modules that can convert MIDI into the Control Voltage signals that modular hardware uses. This is useful for both synchronization and sequencing.
For sync, your DAW can send out MIDI Clock that is commonly used to sync up MIDI hardware, like external sequencers and drum machines, to the tempo of your project. Via a MIDI-to-CV converter, this can be changed into a voltage pulse and used to clock your modular and run its sequencers, gates, triggers and modulations in time with your project.
Once the two are locked together, recording and layering tracks becomes much more manageable. You may even decide to record a software track alongside. Maybe add some pads from a large software synth, explore the sounds of orchestral strings, add sampled drums, or perhaps start dropping in some loops and hits in interesting places. There’s no reason why modular has to stand alone inside your DAW. You can process it, rework it and add to it like any other track in any other project.
Which brings us to sequencing. With your trusty MIDI-to-CV module patched in you can start sending pitch (MIDI note) and gate (note on/off) information through your modular from MIDI tracks in your DAW. It opens up a whole other world of musical connection. You don’t have to be restricted to the 8 or 16 steps of your hardware sequencers you can compose entire symphonies on your computer and play your modular oscillators and trigger their envelopes just like any other hardware synthesizer. Or you can keep it simple with MIDI loops of a few notes. But now you have the capacity to copy/paste patterns and transpose with the click of a mouse, something that can be hard to do in Eurorack.
The MIDI-to-CV module gives you options that can expand the musical potential of your modular system as much or as little as you like.
MIDI should be enough, right? It could be, but it could also be argued that MIDI doesn’t really capture the essence of analog control voltage. Sure you can fire off notes and on/off triggers and even send out some modulation, but CV is very different in how it can be used and blended in the system. First of all, CV has an infinite resolution and can be continuously variable. MIDI only has 128 values to play with. That can result in filter sweeps feeling “stepped” or quantized. CV can be pushed and blended together to form shapes of modulated modulation that you simply can’t replicate with MIDI.
Since CV is like an audio signal running down an audio cable, couldn’t that audio just be recorded into the DAW or played back out to control the modular? Couldn’t your DAW just work with CV directly? With the right software it can, however, it depends on the technical specifications of your audio interface.
Unlike an audio signal, CV is not always moving. Audio is a waveform and has a frequency which is usually in a range we can hear. CV can move and have a frequency but is often really low, like in a Low Frequency Oscillator (LFO) used for controlling the movement of something. Or it can have a frequency of zero where it is being a fixed voltage like sounding the pitch of a note or setting a parameter to a certain level. Most audio interfaces have filters built into the inputs and outputs to remove very low frequencies that we can’t hear so that they can’t affect or add noise to the signal we want to hear. This means that most audio interfaces will filter out the recording or playing back of CV.
However, there are a growing number of audio interfaces that are “DC-coupled” meaning they don’t have those filters and will let flat DC voltages through. With the right software you can use these audio interfaces to move CV in and out of your DAW giving you proper modular style control over your Eurorack.
DC Coupled audio interfaces:
What sort of software? Currently, both Ableton Live Suite (version 10.1) and Bitwig Studio 3 have tools inside that will generate CV to send to hardware and respond to incoming CV to control software elements. A set of plug-ins called Silent Way from Expert Sleepers can be used in any DAW to do the same thing. Other software such as Audulus or Reaktor from Native Instruments can send CV out of its own modular environment to integrate with hardware.
You can then sequence and modulate with potentially more complex and advanced tools than what you may have in your Eurorack alone. And it doesn’t have to go all in one direction. You can pump interesting waveshapes, modulation and probabilistically generated sequences of gates back into your DAW to mess around with your software sounds and processing parameters. In some instances this can remain as CV and interact with CV compatible elements in your software and in others it can go through CV-to-MIDI conversion to become MIDI control over anything you like.
You can also use this to sync between your DAW and the modular which enables you to combine all the worlds in all directions and do your creating, recording, layering, processing and modulating all within an integrated space of hardware and software. That’s pretty awesome.
There’s a common misconception that somehow Eurorack needs to stand on its own and that your electronic music-making should become “DAWless”. While there is artistic merit in making music away from the distractions of the computer and endless possibilities of the DAW, it can also be extraordinarily useful. How much you integrate these workflows is entirely up to you but with a bit of thought and the right hardware you can build a bridge between these two different worlds and make it as restrictive or as free-flowing as you need it to be.
About The Author
Robin Vincent is a veteran of the computer music industry. Back in the 1990’s he ran the PC Product department at Turnkey, released a couple of books on the subject and helped design the Carillon AC-1 audio PC and bring it to market. From 2006 he ran the UK operation of audio PC manufacturer Rain Computers and in 2013 he formed Molten Music Technology to continue building audio PCs under his own steam. In 2016 he joined the team of journalists writing for music technology news website Gearnews.com taking on hardware and software synthesis duties.
Later on that year Robin launched a new blog, Molten Modular, to follow his journey and exploration of Eurorack modular synthesis.