
SUBTRACTOR SYNTHESIZER
103
Noise Generator
The Noise Generator could be viewed as an oscillator that produces noise in-
stead of a pitched waveform. Noise can be used to produce a variety of
sounds, the classic example being “wind” or “rolling wave” sounds, where
noise is passed through a filter while modulating the filter frequency. Other
common applications include non-pitched sounds like drums and percus-
sion, or simulating breath noises for wind instruments. To use the Noise
Generator, select an Init Patch and proceed as follows:
1. Turn Osc 2 off.
2. Click the button (in the Noise Generator section) to activate the
Noise Generator.
If you play a few notes on your MIDI instrument you should now hear
Osc1 mixed with the sound of the Noise Generator.
3. Turn the Mix knob fully to the right, and play a few more notes.
Now just the Noise Generator will be heard.
➜ Thus, the output of the Noise Generator is internally routed to Osc
2.
If you switch Osc 2 on, the noise will be mixed with the Osc 2 waveform.
There are three Noise Generator parameters. These are as follows:
Phase Offset Modulation
A unique feature of the Subtractor oscillators is the ability to create an extra
waveform within one oscillator, to offset the phase of that extra waveform,
and to modulate this phase offset. By subtracting or multiplying a waveform
with a phase offset copy of itself, very complex waveforms can be created.
Sounds complicated? Well, the theory behind it might be, but from a user
perspective it is just a method of generating new waveforms from existing
waveforms.
A seasoned synth programmer using Subtractor for the first time may won-
der why the Subtractor oscillators (seemingly) cannot provide the commonly
used pulse waveform and the associated pulse width modulation (PWM). Or
oscillator sync, another common feature in analog synthesizers. The simple
answer is that Subtractor can easily create pulse waveforms (with PWM) and
oscillator sync-sounds, and a lot more besides, partly by the use of phase
offset modulation.
Each oscillator has it's own Phase knob and a selector button. The Phase
knob is used to set the amount of phase offset, and the selector switches be-
tween three modes:
• Waveform multiplication (x)
• Waveform subtraction (–)
• No phase offset modulation (o).
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Parameter
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Description
Noise Decay This controls the length it takes for the noise to quieten when
you play a note. Note that this is independent from the Amp
Envelope Decay parameter (see page 110), allowing you to
mix a short “burst” of noise at the very beginning of a sound,
i.e. a pitched sound that uses oscillators together with noise.
Noise Color This parameter allows you to vary the character of the noise.
If the knob is turned fully clockwise, pure or “white” noise
(where all frequencies are represented with equal energy) is
generated. Turning the knob anti-clockwise produces a grad-
ually less bright sounding noise. Fully anti-clockwise the
noise produced is an earthquake-like low frequency rumble.
Level Controls the level of the Noise Generator.
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