Analogue Synths with Nonstandard Waveforms Pt.2

You know, I go through phases with analogue. As a digital (and hybrid) synthesizer enthusiast, it's sometimes hard to be excited about the same building blocks being presented to us in slightly different combinations over and over again - of course, I know it's more nuanced than that! Already owning quite a few SEMs, a few CEMS and quite a number of SSMs, I sometimes wonder if I'll ever buy anything analogue again; of course I do - because in actuality, the outer limits of analogue (and the control over those analogue components) has whole continents left to explore. On that note, we'll be looking at some analogue synths (or modules) that create unusual waveshapes, in a series of articles. Part 2:

Oscillating an Analogue Sequencer / The "Graphic VCO"

So one of my favourite tricks is to create crude, digital-sounding waveforms with the use of an analogue sequencer. Sequencers, of which I basically include any module that can output a series of sequential CV signals, are usually clocked in a moderate LFO range - allowing us to hear what CV value, or "note" is on each step.

However, if we were to clock that sequencer with an audio rate oscillator, the sequence would fly past so quickly that we wouldn't perceive different notes! Instead, one continuous tone, whose brightness and timbre can be shaped by tweaking the sequencer's sliders or knobs; the values of the "steps".

In fact, the steps become akin to a computer bit! In a 4-bit computer, you may have 16 values - each holding a number from 0-15. An oscillating 16 step sequencer, although completely variable (able to reach numbers in-between 0-15) will make similar lofi wave table-like sounds. BTW, 4-bits is called a nibble, cute!

Doepfer call this audio rate technique the "Graphic VCO" (not to be confused with Erica Synth's Digital Wavetable Module!) and demonstrate how to create such a patch using the A-152 Voltage Addressed T&H module:

The Youtube channel While We Were Sleeping demonstrates these principles with primarily an 8-step sequencer and manages to generate a variety of exciting tones! It's also possible to notice here sequencer with sliders (as opposed to knobs) can be useful - because you can make approximations of saw, square and triangle waves as starting points by drawing those shapes with the knobs.

Other Ideas

What good is a static faux 4-bit wave though? Well, it's possible to add movement and interest in a variety of ways:

• Does the sequencer have CV control over transpose, slew, note length or direction? All of these parameters will lead to very different tones.
• Filtering to taste is always an option, but how about a wavefolder in conjunction with the above parameter automation?
• Maybe modulate the clock-giving oscillator with a little noise to see what happens!
• Chorus is always welcome on digital waveforms to bring phatness!

However you approach this experiment, it's important to remember that Sequencers can output DC voltage, so it's probably best to err on the side of caution and send your oscillator through an AC-coupled module before it exits your system - luckily, these are usually plentiful!

Anyhow, happy patching, and let us know how you got on!

Posted by MagicalSynthAdventure an expert in synthesis technology from last Century and Amiga enthusiast.

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