Hands on: Subtractive synthesis

There was a time when synthesizers were pretty rare and only the richest bands could afford them. Even then many bands could only afford one model.

As a result they had to make the most of it by investing time and effort in programming it to produce the best possible sounds.

In fact, bands and studios sometimes even used to pay sound engineers to come in and program their synthesizers for them.

Today we have hundreds of software synths available for our sequencers, and so we’ve become a bit lazy about programming new sounds. After all, why should we bother creating our own patches when these soft synths often come with literally hundreds of pre-set sounds?

Many people probably don’t have the foggiest idea of how to go about programming new patches, or even know the right controls to reach for when they need to tweak a preset to make it fit better with their tracks.

However, it’s never too late to learn the ins and outs of synthesis and how to create new sounds, so this month we’re going to take a look at how you go about programming a synth with a subtractive synthesis engine.

This type of synth engine is used in a vast range of synthesizers, including classic models such as the Roland TB303 and the Mini Moog. Subtractive synthesis is an excellent place to start when learning how to program a synth because it’s a pretty easy synth engine to understand.

Also, because it was one of the first forms of synthesis and was used on lots of instruments, its terms and concepts have been carried over to modern synths, such as those based on Wavetable synthesis. In short, if you can program a subtractive synth engine, you can have a stab at programming almost any type of synthesizer.

Getting started
For the purposes of this column we’re going to use the Subtractor synth in Reason v3.0, but most of the principles we’ll be covering can be applied to synths in other programs, as long as they use a subtractive engine.

To get started, load up Reason and then add a mixer and the Subtractor synthesizer into a new rack. The starting block of any sound in a subtractive synth patch is the waveform created by the oscillator.

Subtractor offers a number of different waveforms, but the first four shapes are the ones that are common to most analogue synths. These waveforms are the sawtooth, square, triangle and sine. Try changing between them and playing a note on your keyboard to hear the different sounds they produce. For example, you’ll find that the sine wave has a pure tone, while the triangle has a harsher sound.

Subtractor has two oscillators, so you can play the two waveforms from these oscillators off against each other to create a more interesting sound. Try it out by first setting the OSC1 waveform to the sawtooth shape and then turning on the OSC2 waveform by clicking the red light next to its name.

Playing both oscillators together adds a meaty feel, but we can thicken the sound up even more by detuning the second oscillator away from the first. In the Cent box for OSC2 click on the down arrow to change the detune level to –12.

When we detune the oscillators in this way we are putting them out of phase with each other so that they clash slightly and create a ‘beating’ effect.

We can make the sound even more interesting by transposing the second oscillator down by a couple of octaves. In the Oct box for OSC2 click on the down arrows to change the setting from 4 to 2. You’ll notice that the patch has become deeper and more bassy.

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