Reason: Long Live Subtractor!

Screen 1: Subtractor is great for gritty acid mono bass lines, especially paired with the Matrix.

We revisit Reason’s venerable virtual analogue, Subtractor.

I was musing on what the core parts of the Reason Rack are, and looking back to the first release in 2000. That original release had a drum machine, a loop player, a sampler and a synth, and along with the step sequencer and effects it felt like enough to do just about anything! A large part of that was down to the combination of sonic versatility and processor efficiency of the synth: Subtractor. I also realised that I haven’t dropped a Subtractor into my Rack for years. Europa has become the modern workhorse synth in Reason, and there are so many other synth gems like Complex‑1, Parsec, Grain and Algoritm to explore.

I guess I assumed that Subtractor had been left behind sonically, as the next‑generation Rack devices could take advantage of faster processors and advancements in virtual instrument programming. So when I started thinking about devoting a Reason column to this classic device, I thought of it as an interesting throwback. But now I’ve fallen back in love with Subtractor and realised it still has lots to offer. As well as doing the usual things a virtual analogue subtractive synth can do, it has really interesting oscillators, and has a kind of bite and presence that feels right at home in the current revival of ’90s dance, garage and jungle vibes, as well as classic hip‑hop basses and melody lines grimy enough for contemporary drill beats. Subtractor surely contributed as much to noughties bass music as NI’s Massive. Instead of thinking of Subtractor as dated software, I’m now seeing it as a cult classic millennial sound module.

Modern Classic

As the name implies, Subtractor follows a familiar subtractive synth scheme, with dual oscillators (plus noise) running through two filters. Onboard modulation comes from three envelopes and two LFOs, plus there are straightforward ways to map in external mods from aftertouch, velocity, mod wheel, etc. In fact because everything is set up from dedicated knobs and buttons, Subtractor is a fantastic instrument to use to teach or learn synthesis.

I’m going to devote most of our time here to exploring the oscillators, as they are the main thing that make Subtractor interesting to this day. The oscillators are each capable of producing one of 32 waveforms. You can step through these with the small buttons next to the waveform display, or click and drag in the display itself to scroll through. The first four waves are your standard analogue subtractive starting points: sine, saw, square and triangle, and are displayed graphically. The rest are just shown as numbers and form a collection of more complex waves. They are not wavetables, they are simply static, cycling waveforms. However, while they are static harmonic starting points, the oscillators can be animated with movement and complexity via the gift of FM, and Subtractor’s own special sauce: phase offset modulation.

Screen 2: A simple sawtooth wave running with Phase Offset off.

Phase Offset Modulation?

Screen 3: The same saw using Phase Subtract mode creates a square that can be pulse‑width modulated with the Phase knob.On the left of each of the oscillator panels is a Phase knob and a three‑way mode selector marked in shorthand for Multiply, Subtract and Off. This Phase control is not a pulse‑width modifier in the traditional sense, although it can be used to get similar results. It’s also not Phase Modulation (which is basically equivalent to Frequency Modulation) or Phase Distortion as utilised by Casio synths. What the Phase modes on Subtractor do is double up the current waveform, then either multiply the two copies together, or subtract one from the other. The Phase knob offsets the time sync between the two copies of the wave. This can completely change the oscillator outputs, but in surprising and harmonic ways.

To show what’s happening I’ve used the excellent MOscilloscope VST plug‑in from MeldaProduction (which is also handy for seeing what all those numbered waveforms look like). In Screen 2 I’ve got a single sawtooth wave running with Phase Offset Mod disabled. In Screen 3 the Phase Subtract mode is selected, and you’ll see that the result is a square wave. Adjusting the phase now gives you pulse‑width modulation. In Screen 4 the Multiply mode is active, and you get something different and more harmonically rich. Adjusting phase here also gives a pulse‑width mod type effect, but with a more buzzy character.

Screen 4: With Phase Multiply mode you get something completely different that can also be swept in interesting ways with the Phase control.Every waveform responds to these manipulations in different and interesting ways. In general, the negative mode gives you something like PWM, or sometimes a comb‑filtering type result. As you reach the fully in‑phase position (anti‑clockwise) the waves cancel each other out. Multiply produces harder, more harmonic shaping, but more manageable than FM.

Modulation

Subtractor has two oscillator cross‑mod options that extend its sonic range: FM and Ring Mod. Both of these require that you turn on osc 2 by clicking the small LED button next to its name. The FM knob applies frequency modulation of osc 1 by osc 2. This can be modulated by the mod envelope, velocity, LFO 1 and the mod wheel. The Mix control lets you hear just the modulated osc 1, or a blend of both oscillators. Ring mod is a simple on/off switch, and the ring‑modulated sound is heard at the osc 2 output.

Combining all these oscillator options and bringing in some modulation is what makes Subtractor so versatile. The modulation system is dead easy. Each mod source has a dedicated panel, some with a series of knobs for applying modulation, and some with switches. The switched modulators (LFO 1 and mod env) can only be applied to one destination from the panel. However, if you flip the Rack around (Screen 5) you can manually patch these sources. You can use a CV splitter if necessary. Another cool trick is to create an internal macro by assigning the mod wheel to multiple places, and then send CV to it.

Things To Try

It’s definitely worth browsing the presets to get an idea of what Subtractor can do and a feel for its character. But here are some things to try. Starting with the classics, Subtractor is great for Acid (see Screen 1). To get an authentic monophonic response with glide for this and for 808 basses, set the Polyphony to 1, add a short Portamento time and switch to Legato mode. Try sequencing from the Matrix. The filters have a wonderful stickiness and ring to them that make sounds punch through, and you can really add some grit with the slightest touch of FM applied from the mod env.

Screen 5: If you want to build your own signature dirty 808 bass, Subtractor has you covered.

For deep grimy basses (Screen 5), apply the mod env to pitch and try linking the filters. Set filter 1 to high‑pass, and add resonance and maximum key tracking. Tweak to find the fundamental sub frequency to boost. Then set filter 2 as your low‑pass. Try messing around with different sounds on osc 2 to use for FM or even to blend in a little for some dirt that will mostly get filtered out.

Subtractor has a way of making itself noticed and is still worth reaching for in all kinds of situations.

Subtractor can also do lots more. Try applying a Phase Offset mod to a square with the mod env and you open the door to lots of Oberheim‑like polys. Hunt through the other waveforms, many of which are designed as starting points for synthesized pianos, organs, guitars and basses (try the patch shown in the main screen). Wind in some phase and FM modulation to get bananas dubstep wobbles and rhythmic vowel bursts. Subtractor has a way of making itself noticed and is still worth reaching for in all kinds of situations.