Manual

ANALOG CONTROLS
The MOD W setting will route the Mod Wheel messages from a MIDI keyboard to modulate Oscillator
A’s frequency. With your mod wheel set to 0, there will be no affect on Oscillator A’s pitch. Increasing
the value of your mod wheel will cause Oscillator A’s frequency to increase accordingly.
The WAV B setting routes Oscillator B’s waveform, as determined by the WAVE B control setting, to
modulate the frequency of Oscillator A. Use this to create direct FM sounds when Oscillator B is in its
audio range, or more traditional vibrato effects when Oscillator B is producing frequencies below the
audio range. Note that all of Oscillator B’s waveforms range from –5 to +5 volts, causing Oscillator A’s
frequency to rise above and fall below the normal frequency for a note’s pitch.
The B ENV setting lets Envelope 1 control the amplitude of Oscillator B’s waveform, as determined by
the WAVE B control setting, to modulate Oscillator A’s frequency. This provides a more traditional
form of FM where the modulation source varies its amplitude over time.
The + ENVELOPE setting selects the positive polarity of Envelope 1 to sweep the frequency of
Oscillator A. Since envelope 1 has a range of 0 to +10 volts, this will cause Oscillator A’s frequency to
rise above the normal frequency for a note’s pitch.
The - ENVELOPE setting selects an inverted polarity of Envelope 1 to sweep the frequency of Oscilla-
tor A. Although Envelope 1 is now inverted it is also level-shifted keeping it in the 0 to +10 volts range
just as the positive polarity envelope. This will cause Oscillator A’s frequency to rise above the normal
frequency for a note’s pitch.
NOTE: Most traditional synthesizers with a negative polarity envelope would have a range of say
0 to –10 volts. The problem with this is if Oscillator A is our main audio source covering the entire
audio range, if we begin applying negative voltages to the frequency of an oscillator, the pitch can
be easily pushed below the audio range making it useless as an audio source. Instead the XS keeps its
inverted envelope in the same voltage range as the positive polarity envelope to keep this oscillator
within the usable audio range.
23