Any continuous bipolar waveform may be multiplied by itself to give a doubled frequency, discontinuous square or pulse waves will produce a DC offset and sawtooth waves produce the same frequency with altered harmonics.
A sine wave will produce another sine wave an octave higher according to the trigonometry equation for squaring a sine.
sin² (A) = (1 - cos (2A))/2
Normalled connections allow this patch to be made with a single patchlead.
Two Squares from one Modulator
A variation of the above squaring may be patched using the factorisation of the difference of two squares:
sin² (A) - sin² (B) = (sin (A) + sin (B)).(sin (A) - sin (B))
By multiplying the sum with the difference of two signals the squares of both are produced with a single multiplication.
In the case of two sine inputs this will double the frequency of both with no cross products and Modulator B is free for
other use.
Shape Modulation
Waveforms from the same VCO may be multiplied to produce different wave shapes.
A triangle multiplied by a square gives a sawtooth an octave higher.
A sawtooth multiplied by a square gives a triangle.
A pulse wave may be multiplied by other waveforms from the same VCO and then width modulated.
A sawtooth multiplied by a pulse gives a triangle at 50% width and changes to a positive or negative sawtooth at 0% and 100%.
Complex Shape Modulation
Adding another VCO synchronised to the lower frequency generating the pulse enables a rich palette of waveforms to be created and modulated.
EMS-style Shape Modulation
Voltage controlled shape by full wave rectifying a sawtooth with an offset which varies from sawtooth through triangle to inverted sawtooth.
Centre Dead Zone
Voltage controlled shape by adding positive and negative rectified halves with a common complimentary offset.
Clipping
Voltage controlled limits by adding a CV offset, rectifying and then subtracting the offset to restore the DC level.
Or the reverse.
Another inverter/summer, e.g. PinMix or SwitchMix, is required to do both positive and negative clipping.
LFO Modulation Processing
LFOs with ±5V outputs require accurate reduction for control of vibrato and trills.
The dual level controls provide a coarse and fine attenuation for exact pitch depths and the positive half wave rectification can be used for unipolar trills.