Planning the expansion of my modular synth

I have a very modest modular synth which I have been building for the past year. I recently watched the complete “Modular In A Week” (MIAW) series on YouTube and was inspired to follow its example of making solid incremental contributions to my rig.

The MIAW series follows a conceit of each “day” of the week being devoted to constructing a single type of synth module: VCOs, VCFs, LFOs, etc. In my adaptation of the plan, I will work “across” the week to make a “voice” comprised of the VCOs, VCFs, and other modules typically found in a monophonic synth.

The capabilities of a MiniMoog, Monologue, or Neutron appear modest from the specifications, but are all very musically capable. Using these monophonic synths as examples, I’m defining a voice to have the following  characteristics:

  1. A pitch-controllable oscillator (VCO, PDO, wavetable Osc.)
  2. A means to change the timbre of that oscillator (VCF, chorus, waveshaper, the inherent parameters in FM or PD)
  3. A means to change the volume of that oscillator (VCA)
  4. A source of continuous modulation (LFO, looping ADSR)
  5. A source of triggered, time-limited modulation (ADSR, AR, AD)

These don’t map neatly to single modules each except in the traditional VCO+VCF+VCA+ADSR+LFO configuration. A module like a Low Pass Gate (LPG) is both a way to modify timbre and a way to modify volume. Various oscillator types are able to modify their own timbre: Phase Distortion Oscillators, Frequency Modulation Oscillators, and even a dual VCO which can hard sync the second oscillator from the first. This why I’m thinking of a voice in terms of the above five capabilities and not in specific modules.

So using this framework, how what is my current setup?

  1. Voice 1: A Behringer Neutron semi-modular
  2. Voice 2: A collection of 8 modules (more or less)
  3. Voice 3: Volca Bass
  4. Voice 4: Volca Sample

The Volca Sample brings up an interesting edge case. How are drums accounted for? Does each channel of a drum synth (ie: bass drum, snare, high hat, etc) each count as “a voice”? Typically you cannot vary each parameter in these synths. I pragmatically count all the drum channels together as a single voice. Adding a second bass drum doesn’t significantly change the ability of a drum synth. I only plan to have a single drum pattern running at a time – it really only varies in it’s level of sophistication, not in its duplication.

This brings up another topic: live performance capabilities. Other than changing the patch and tweaking parameters, my primary methods during live performance is the use of sequencers and keyboards.

Currently, I have a Korg SQ-1 for unifying the various sequencing systems (MIDI, CV/gate, Volca sync) and an Arturia Keystep for live performance. I want to be able to make use of all the voices in my modular, so I will have at least a sequencer or keyboard per voice. Ideally a sequencer could be swapped for a keyboard and vice-versa, so I’d like to move towards a unified CV/gate system. This will require a more sophisticated way of relating these sequencers to each other than simply chaining them. I will also need a way of combining all the voices together for a final mix.

To satisfy this, I’m considering a third group of modules I’m simply calling “Utilities”. This will include clock dividers, logic gates, mixers, multiples, and effects like delay, chorus, or distortion. It’s also a place to put more esoteric modules such as a digital sampler, the MTM “Turing Machine” random sequence generator clone I built, and an oscilloscope display. These are useful and interesting but don’t ultimately increase the musical capability of the synth in a way I’ve found interesting.

Putting this all together, then, what is my goal? Using some of the classic game system sound capabilities as a guide, my synth should have:

  1. 3 voices, as described above
  2. 1 drum voice, with at least 4 channels
  3. 3 sequencers
  4. 1 keyboard
  5. Utility modules as needed

My next step is to plan out these voices and work towards constructing the first one.