Arturia PolyBrute, User Manual

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4.3.4. VCO 2
VCO 2 is very influential: it can force VCO 1 to sync its harmonics (Sync 2 > 1 above),
modulate its fundamental frequency ( FM 2 > 1 [p.24] ), modulate VCF 1 ( VCO 2 > VCF 1 [p.31] ),
and appear directly in the mixer, all at the same time. Plus it has a descendant: a sub-
oscillator, described in the next section.
VCO 2 has two controls that VCO 1 does not:
4.3.4.1. Sub
The sub-oscillator produces a sine wave that is always an octave below the fundamental
pitch of VCO 2. It is not shaped by the VCO 2 waveform mix (saw, triangle, square), but
when added to the output of VCO 2 it can modulate VCO 1 and VCF 1 (through Sync 2 > 1 and
VCO 2 > VCF1, respectively).
The Sub knob adjusts the VCO 2 mix between no sub-oscillator (full left), equal parts
fundamental and sub-oscillator (halfway up), and sub-oscillator only (full right). The
following pictures illustrate the effect the sub-oscillator has on a pure sawtooth wave from
VCO 2:
Note that the energy output of VCO 2 is greater when the sub-oscillator mix is at 50%, since
both sources are present.
4.3.4.2. FM 2 > 1
FM (Frequency Modulation) is when the frequency of one oscillator is used to modulate the
frequency of another. The FM 2 > 1 control lets VCO 2 do this to VCO 1. The result is very
different than simply mixing the two oscillators together. In fact, you can hear this effect
even if the Mixer level for VCO 2 is zero.
For example, try this:
1. Set both VCO waveforms to Triangle and turn up both in the Mixer so you can
tune VCO 2.
2. Play a note and turn VCO 2 all the way down in the Mixer.
3. Now gradually raise the FM 2 > 1 level. The tone becomes increasingly complex,
even though you're only hearing VCO 1. This is the effect VCO 2 is having
upon VCO 1. This effect will also be modified if you change the VCO 2 pitch or
waveform mix.

♪
: A high FM 2 > 1 value can heavily affect the pitch. But using it in combination with a high Sync 2 >
1 value can provide steady pitched tones with complex harmonic content.
Sub-oscillator level = 0% Sub-oscillator level = 50% Sub-oscillator level = 100%
24 Arturia - User Manual PolyBrute - Voice Architecture