User Manual

SUBTRACTOR SYNTHESIZER
(RECORD+REASON)
537
Frequency Modulation (FM)
In synthesizer-speak, Frequency Modulation, or FM, is when the frequency of one oscillator (called the “carrier”) is
modulated by the frequency of another oscillator (called the “modulator”). Using FM can produce a wide range of har-
monic and non harmonic sounds. In Subtractor, Osc 1 is the carrier and Osc 2 the modulator. To try out some of the
effects FM can produce, proceed as follows:
1. Select an Init Patch by selecting “Initialize Patch” from the Edit menu.
2. Activate Osc 2.
As you need both a carrier and a modulator to produce FM, turning the FM knob will not produce any effect unless
you first activate Osc 2. For classic FM sounds, use sine wave on oscillator 1 and triangle wave on oscillator 2.
3. Use the FM knob to set the FM amount to a value of about 50.
As you can hear, the timbre changes, but the effect isn’t very pronounced yet.
4. Turn the Osc Mix knob fully to the left, so that only the sound of Osc 1 is heard.
The modulator (Osc 2) still affects Osc 1, even though the Osc 2 output is muted.
5. Now, hold down a note on your MIDI keyboard and tune Osc 2 a fifth up from the original pitch by setting the
Osc 2 frequency “Semi” parameter to a value of 7.
As you can hear, for each semitone step you vary the Osc 2 frequency, the timbre changes dramatically. Setting
Osc 2 frequency to certain musical intervals (i.e. fourth, fifth or octave semitone steps) produces harmonic, rich
timbres, almost like tube distortion. Setting Osc 2 to non-musical intervals usually results in complex, enharmonic
timbres.
q Experiment with different oscillator parameters such as phase offset modulation, changing the waveforms etc.
and listen to how they affect the sound of frequency modulation.
Using the Noise Generator as the Modulator source
As explained earlier, the Noise Generator is internally routed to the Osc 2 output. Hence, if you deactivate Osc 2, and
activate the Noise Generator while using FM, the noise will be used to frequency modulate Osc 1.
q With the Noise Generators default settings, this will sound much like colored noise. But by changing (lower-
ing) the Noise Generator Decay parameter, so that the noise modulates only the attack portion of the sound
can produce more interesting results. You could also use a combination of noise and Osc 2.