Future Retro XS - Manual (Page 19)

ANALOG CONTROLS
OSCILLATOR A
Oscillator A is one of the main audio sources in the XS, although it can also be used as 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.
OCTAVE: This control is used to transpose Oscillator A 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,
and the 4 setting produces 523.25 Hz. If we were to leave this octave setting in the 4 position, and play
our highest MIDI note C7, we would find that this oscillator produces a frequency of 16,744.04 Hz or
16.74 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 16 kHz. We will discuss later in the manual how to access this oscillator’s
full range.
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 A will produce a
frequency of 32.703 Hz. If the CV IN voltage changes to +5 volts with the octave control changed to 4,
Oscillator A will then produce a frequency of 16.74 kHz.
FINE TUNE +/-: This is the master fine tune control for both Oscillators A and B. When this control is
set to its mid position marked with a “0” both oscillators should be in tune. This control covers a range
of approximately 12 cents total, providing us with –6 to +6 cents in detuning. Rotating this control
counter clockwise of the “0” mark will cause both oscillators to sound flat. Rotating this control
clockwise of the “0” mark will cause both oscillators to sound sharp. You can use this control to match
the pitch of the internal oscillators to an external reference if they are slightly out of tune with one
another.
WAVE A: This control selects which waveshape will be used for Oscillator A. Although Oscillator A
actually only generates the sawtooth and square waveforms which will track the playing of notes up and
down a keyboard.
The SAWTOOTH setting selects Oscillator A’s sawtooth waveform.
The SQUARE setting selects Oscillator A’s square waveform, which has a 50% duty cycle.
The NOISE setting will select the internal white noise source, which contains an even amount of
frequencies throughout the audio spectrum.
The EXT setting will select any external audio source that is inserted into the AUDIO IN jack.
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