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Oscillators – Dave Smith Instruments MOPHO SE User Manual

Page 19

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Oscillators

The Oscillators section contains the primary controls for Mopho’s two digitally

controlled analog oscillators or DCOs. “Digitally controlled” does not mean the

oscillators themselves are digital, just that the oscillators’ frequencies are under

digital—rather than voltage—control. The advantage to that is that the tuning is

exceptionally stable over a ten-octave range without having to compensate for

variables like temperature. The audio signal path is still completely analog.

Oscillator Select

Choose oscillator 1, oscillator 2, of both. When both 1 and 2

are selected, changes made to the other oscillator parameters affect both

oscillators.

Frequency: C 0…C 10—

Sets the base oscillator frequency over a 10 octave

range, from 8 Hz to 8KHz, stepping in semitones. C3 is middle C, the first

octave is 0 (C0, C#0, etc.), the second octave is 1 (C1, C#1, etc.), and so on.

Fine Frequency: -50…+50—

Fine tune control with a range of a quartertone up

or down. Zero is centered. Steps are in cents (50 cents = 1/2 semitone).

Shape Select: Sawtooth, Triangle, Saw-Tri, Square, Off

—Selects the oscillator

waveshape. If none of the shapes are lighted, the oscillator is off.

Pulse Width: 0...99

—Sets the pulse width or duty cycle of the square wave. A

value of 50 results in a true square wave with equal alternating high and low

levels. Increasing or decreasing the value from 50 causes the waveshape to

become asymetrical. Lower values narrow the postive-going portion of the

Sawtooth

Triangle

Saw-Triangle

Square