Future Retro XS - Manual (Page 20)

ANALOG CONTROLS
OSCILLATOR B
Oscillator B is similar to Oscillator A in that it can be an audio source or a modulation source. This is a
wide range, ultra-stable oscillator capable of generating frequencies from approximately 0.5 Hz to more
than 100 kHz.
SYNC: Oscillator B has the ability to sync its waveform to the pitch that Oscillator A is producing.
When this SYNC switch is in the ON position, every time Oscillator A’s waveform goes through a
positive transition (once every periodic cycle), it will force Oscillator B to start regenerating its
waveform shape. This then will cause Oscillator B to start introducing new harmonics in each of its
waveforms. In order to really hear this sync effect, however, you will want to make sure the frequency
of Oscillator B is always higher than that set for Oscillator A. When the SYNC switch is set to the OFF
position, Oscillator B will produce its four waveforms with their original harmonic content.
OCTAVE: This control is used to transpose Oscillator B through its different ranges. Zero is the default
setting for this control. If we were to play note C2 on a MIDI keyboard and switch through the different
octave ranges we would find that the –1 setting produces 16.352 Hz, the 0 setting produces 32.703 Hz,
the 1 setting produces 65.406 Hz, the 2 setting produces 130.81 Hz, the 3 setting produces 261.63 Hz,
the 4 setting produces 523.25 Hz, and the 5 setting produces 1,046.5 Hz. If we were to leave this octave
control in the 5 setting, and play our highest MIDI note C7, we would find that this oscillator produces a
frequency of 33,488.08 Hz or 33.48 kHz. As you can see, using just this octave control and a 5-octave
keyboard, we can cover the frequency range of 16 Hz to 33 kHz. Octave settings from –2 to –6 will
cause Oscillator B to generate frequencies below the audio range (as low as 0.5 Hz in frequency, or 2
seconds of time) when C2 is played on a MIDI keyboard. This is useful when using Oscillator B as a
modulation source. In this way, Oscillator B acts more like a second LFO in the XS. The benefit of
using Oscillator B as an LFO is that its frequency can either be stationary or can track pitches played on
a keyboard.
Remember, the CV Track control in the PITCH CONTROL section can be used to determine whether
Oscillator B’s frequency will track notes played on a keyboard or remain at a stationary frequency.
NOTE: When using an external control voltage to control the oscillator, MIDI note C2 = 0 volts,
C3 = +1 volt, C4 = +2 volts, C5 = +3 volts, C6 = +4 volts, and C7 = +5 volts.
Therefore, with an octave setting of 0, if we input 0 volts into the CV IN jack, Oscillator B will produce a
frequency of 32.703 Hz. If the CV IN voltage changes to +5 volts with the octave control changed to 5,
Oscillator B will then produce a frequency of 33.48 kHz.
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