Each voice path includes a single oscillator; initial tuning and modulation are set in the PITCH section.
RANGE- Sets the coarse pitch range for each oscillator in semitone intervals from -12 to +51. We didn't make up these somewhat odd settings; they're straight from the original instrument. We suspect the far-greater upper range was implemented to best take advantage of Chroma's ring modulation and oscillator sync capabilities.
FINE TUNE- Sets the fine tuning up or down one semitone in cents. This useful for detuning when stacking oscillators.
MOD 1/2/3 SELECT- These configure pitch frequency modulation. Most of these are self-explanatory, so we've included notes only where necessary. Note that none of these mod sources have "inverted" options, because their associated mod depth controls are bipolar - for inverted modulation, simply set the appropriate DEPTH control to a negative value.
Keyboard Glide A- Slewed keyboard CV is used as a mod source (GLIDE RATE control must be set to a non-zero level).
Sweep A
Envelope 1A
Envelope 2A
Keyboard Glide B
Sweep B
Envelope 1B
Envelope 2B
Mod Wheel
Pitch Bend
Controller 1
Controller 2
Velocity
Threshold Velocity- Switches between two discrete pitch mod amounts according to velocity. The velocity threshold is set using MOD THRESH in the CONTROL section.
Keyboard- Sweep rate increases as higher notes are played on the keyboard.
Keyboard Inverted- Sweep rate decreases as higher notes are played on the keyboard.
Velocity- Playing harder increases the sweep rate.
Velocity Inverted- Playing harder decreases the sweep rate.
Aftertouch (Mono+Poly)
Threshold Aftertouch- Switches between two discrete pitch mod amounts according to aftertouch. The aftertouch threshold is set using MOD THRESH in the CONTROL section.
MOD 1/2/3 DEPTH- Sets the amount of mod from the same-numbered mod source.
Note that MOD 3 DEPTH's range differs from the others - instead of ranging from -100 to +100%, it ranges from -64 to +64 in half-step increments. This was done to simplify setting bend depth when assigning the pitch bend wheel. (Unlike most synths, the Chroma doesn't have a "hard-wired" mod bus for pitch bend.)
IMPORTANT NOTE ABOUT PITCH MOD - YOU REALLY SHOULD READ THIS
Now that we have your attention... we wanted to be sure users were aware of another of Chroma's unusual quirks. Each of the three PITCH section mod buses has a different mod range and max setting as follows:
MOD 1- major 3rd
MOD 2- octave+major 3rd
MOD 3- five octaves+major 3rd
The idea behind is was that the three mod buses would be used for different applications, depending upon the range needs. For example, MOD 1 could be used for subtle vibrato via the sweep section, where only a very limited amount of pitch deviation was necessary. MOD 2 might be used for siren effects, and MOD 3 could be used with the sync or ring mod patch configuration settings, when very wide pitch changes are desired.