USING FM AND OSCILLATOR SYNC TO BRING ANALOGUE BASS TO LIFE

Audio-rate modulation is the main technique behind synths like Yamaha’s DX7, but a more basic version can be used in many analogue or analogue-style synths. Let’s use a touch of FM as well as oscillator sync to add harmonic interest to a simple bass sound

1 We’re starting with a simple analogue-style bass patch from Arturia Pigments. It uses a square wave with a sine sub-oscillator provided by the Utility Engine. A low-pass filter with a short modulation envelope is adding a punchy attack. It’s a decent sound, but hardly original.

2 Pigments’ analogue engine lets us apply frequency modulation to oscillators 1 and 2 using Osc 3 as a source. For now, let’s keep the volume of Oscillators 2 and 3 down to zero, but we increase FM to osc 1 a little to 0.020. Our square wave starts to sound ‘hollow’.

3 Altering the shape and tuning of Oscillator 3 lets us get creative with this effect. Tuning Osc 3 up by seven semitones, adding a little detune and switching to a triangle wave gives us a more interesting, slightly dissonant tone.

4 Oscillator sync gives us another way to introduce interesting timbres. To try this, we turn off the FM and raise the level of Osc 2. This is set to a pulse wave with a width of 0.800. Now we disengage key tracking for Oscillator 2 but engage oscillator sync instead.

5 This effect becomes most interesting with modulation. We set up LFO 1 to modulate to coarse tuning of Osc 2. Oscillator sync keeps this from sounding too harsh, but it still creates an interesting timbral effect.

6 We now reintroduce the FM effect too, experimenting with different wave shapes as well as modulation levels/speeds lets us create all sorts of unusual effects.