While friend astronaut was teaching sci fi I’ve been reading a lot of synthesis lessons trying to get a feel for how I would go about this. I thought the best thing is to work with a particular synthesiser, choosing Ichiro Toda’s Synth1. This free VST instrument is intended as a virtual Clavia Nord Lead, which in turn is an idealised analogue subtractive synthesiser. (Synth1 is not available for the Macintosh, sorry, but I am sure you can substitute something far more fabulous than Windows users could possibly dream of.)
Please download and install the synthesiser, and having had a play around, make sure to select an Initial Sound preset. There are four yellow glowing buttons, click each to turn them off. In the filter section, turn the frq knob all the way to the right. Save this – it’s a flat unprocessed sound.
The preset sounds are vile, even the author says this. Ignore them. But once you know the Synth1 synthesiser, sound design is extremely obvious and enjoyable. We’re going to take several posts looking at it rather than skimming over the whole thing too quickly.
The work flow is from the top left to the bottom right. You should try to operate things in that way to not end up chasing your tail for a sound.
Two oscillators are controlled by the first panel. They create the raw waveforms that we modify and their setting usually has the greatest influence on the sound. There are two because well known recipes require the two voices in combination – two are far more powerful than one, but three does not have such a large advantage over two.
Please try playing with each of the controls I mention to quickly see what they do. This is the quick and easy way to get the idea.
Look at oscillator 1. Buttons set one of four wave shapes: sine, saw, triangle, square. Sine is the fundamental with no overtones – there is nothing to filter out or accent, it is very pure and therefore voluminous. You would for example use this as the basis of a deep ‘house’ bass. Saw is a rasping sound, like a violin. It’s rich in overtones, and responds best to filters, so this is the best for complex sculpting – as well as strings generally. Triangle, less rich than the saw but still has overtones that can be tweaked into electric pianos. Square – a hollow reedy, pipe sound. Choosing the right wave shape is the primary design choice. Want pipes? Choose square. And so on.
Below you see that Oscillator 2 has similar wave shapes: triangle, square, saw, noise. Noise is ‘white noise’ – a loud hiss. Already you can see that you might add different shapes for complexity or have two of the same for consistency. A nice bass might use a sine and a saw in combination – the sine for depth and the saw for bite.
Looking at 1 again – the knob just to the right creates 8 copies of the wave shape and detunes them – a process often called ‘multi-wave’. A little detuning creates a chorus, thickens the sound, without requiring our other oscillator. For example piano strings are grouped and slightly detuned – the sound is richer that way. But detuning is like sugar, leads to fatness, not always healthy. If everything is chorused it’s easy to get a cloudy mess.
Next along is FM or frequency modulation, where the note of oscillator 1 is modulated by the note of 2, causing bell like inharmonics when they are detuned. (A string vibrates along one axis, a bell along many, therefore mixed note harmonics occur). (This is not quite the same as the FM in a FM synthesiser like the DX7 where phase modulation is constrained by an algorithm in that machine. The inharmonics will not be consistent across the notes.) You use this for bells, metal, and to sweep a sound with a bright cluster of harmonics e.g. for complex bass notes.
Below in Oscillator 2 is Ring modulation (or AM). With this turned on, the two waveforms are multiplied rather than added. This causes the shapes to slice into each other, more obvious as they are detuned. Again it could be described as bell like but with a more square mechanical sound from the slices. FM and ring can’t be used together. This is the way for dramatic sweeping noises, we’ll be making a few by the end of all this.
Sync is a control that forces the 2nd oscillator to keep time with the 1st. Imagine you have set the 2nd to a lower pitch. You sync it to the 1st. It is interrupted into playing only the first portion of its shape. Changing the pitch of 2 doesn’t change the note it plays, instead it slices the waveform at different points introducing interesting groups of overtones.
When track is off, osc. 2 plays the same note no matter which key you play, when on the note scales as normal. You’ll occasionally want sounds where a static tone is part of the mix, perhaps to emulate a resonance of a room.
Pitch steps the note of oscillator 2 up or down by note in relationship to 1. You can set up a fixed ratio between the oscillators e.g. thirds and fifths for double reeded instruments. Often you will step this down to -12 which places the two an octave apart. On some synthesisers this relationship is preset by making 2 a sub-oscillator. One reason being that as you play high notes, the sub-oscillator keeps the sound at around the same volume. Otherwise as you play higher, the sound becomes thinner. Fine shifts the note of osc.2 in smaller amounts. It is this pitch that you adjust to create sync, FM and ring effects.
Below both oscillators is Modulation Envelope. An envelope is a shape, triggered by a note being played, that controls the level of a signal. Traditionally the shape is defined by four controls – the duration of the attack in which the level rises from 0 to maximum, then the duration of the decay in which the level drops down to a sustain amount, held so long as a key is pressed. When the key is released, the release is the duration over which the signal drops to 0 again. Wikipedia can make itself useful.
Here the envelope is just attack and decay with a maximum amount. The envelope is sent to one of three destinations. If osc2, the pitch of osc2 is detuned – good for dynamic sync and ring effects. If FM, then the amount of FM is enveloped which is good for the twang of a bass. If p/w then pulse width is moved, an effect we’ll look at now.
The square wave shape is a rectangle, the width of which is set by pulse width. The more square it is, the more like an organ pipe. When thinner it sounds like a reed instrument. Modulating the p/w control at the right of the oscillator area causes interesting shifts in the sound. You need to have a square wave shape selected to hear this effect.
Here also are pitch controls for the whole sound – key shift to move the whole sound up or down a note at a time, tune to fine tune the synth, and mix to set the balance between the two oscillators. When you use FM, ring or sync, it’s the 2nd oscillator that will carry the effect and so you’d likely turn this to only hear that oscillator. Here also the place to control the mix level of a sub oscillator.
This section is quite intricate and needs practice. We’ll just cover a few ideas. A string section is quickly made by a multi-wave saw shape on 1 with a triangle on 2 an octave below to give depth. A bell might involve a sine on 1, frequency modulated by 2 pitched much higher, the amount of FM controlled by an envelope such that the clang of FM drops off quickly to leave the smooth sine. Cool pipe sounds use detuned square waves on 1 and 2. Screaming sweeps use ring modulation, sending a long modulation decay to the pitch of osc2.
The oscillator section can’t do everything and so once you’re close to an interesting sound you might like to play with the filter section to see what that can do for you. But we’ll come back to that in more detail next time.