Propellerhead Reason - 1.0.1 Manual de Operações descarregar pdf (Página 106)

SUBTRACTOR SYNTHESIZER

104

When phase offset modulation is activated, the oscillator creates a second

waveform of the same shape and offsets it by the amount set with the Phase

knob. Depending on the selected mode, Subtractor then either subtracts or

multiplies the two waveforms with each other. The resulting waveforms can

be seen in the illustration below.

• In example 1, we see two sawtooth waves with a slight offset.

• Example 2 shows that subtracting one slightly offset sawtooth wave

from the other, produces a pulse wave. If you modulate the Phase

offset parameter (with for example an LFO), the result will be pulse

width modulation (PWM).

• Example three shows the resulting waveform when multiplying the

offset waves with each other. As you can see (and hear if you try it),

multiplying waveforms can produce very dramatic and sometimes

unexpected results.

Using phase offset modulation can create very rich and varied timbres, espe-

cially when used along with LFO or Envelopes to modulate the phase offset.

✪ To get a “feel” for this concept, you could study Patches that use

phase offset modulation, and maybe tweak some of the Phase Off-

set parameters to find out what happens. Try “SyncedUp” in the

Polysynth category in the Factory Soundbank for an example of osc

sync or “Sweeping Strings”(in the Pads category) for an example of

PWM.

! Note that if you activate waveform subtraction with a Phase offset

set to “0” for an oscillator, the second waveform will cancel out the

original waveform completely, and the oscillator output will be si-

lent. If you set the Phase Offset knob to any other value than zero,

the sound returns.

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 an-

other oscillator (called the “modulator”). Using FM can produce a wide range

of harmonic 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” pa-

rameter 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 mu-

sical intervals (i.e. fourth, fifth or octave semitone steps) produces har-

monic, rich timbres, almost like tube distortion. Setting Osc 2 to non-

musical intervals usually results in complex, enharmonic timbres.

✪ Experiment with different oscillator parameters such as phase off-

set modulation, changing the waveforms etc. and listen to how they

affect the sound of frequency modulation.

1. The two offset

waveforms:

1. The two offset

waveforms:

2. The result of

subtraction:

3. The result of

multiplication:

Ampl.

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Propellerhead Reason - 1.0.1 Manual de Operações Página 106

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