Through-zero multiphonic signal generator: a precision triangle-core VCO with through-zero linear FM, through-zero phase modulation (900° range), and a harmonics generator separating fundamental, even, and odd harmonic channels for additive-style timbre control. All-analog, 12 HP.689
Capabilities 6
Harmonics Generatorharmonics-generator
Separates fundamental (sine), even (saw at 2× frequency), and odd harmonic channels; each has an amplitude controller (balanced modulator) and dedicated output, plus a full-mix output.689
Ring Modulation / Balanced Modulationring-modulation
Each timbral channel amplitude controller is a balanced modulator, enabling through-zero amplitude modulation (ring modulation) on each harmonic channel.689
Through-Zero FMthrough-zero-fm
Triangle-core VCO supports through-zero linear FM via a dedicated TZFM input with polariser, AC-coupling switch, and bias switch for toggling between TZFM and normal linear FM.689
Through-Zero Phase Modulationthrough-zero-pm
Phase modulator follows the VCO core and provides through-zero phase shift of ±450° (900° total range) at 90°/V sensitivity.689
Second exponential FM input with polariser knob. ±1 V/oct range in audio mode, ~±0.66 V/oct in low mode.689
Flip Input
trigger
—
Soft sync input. Flips the oscillator direction without instantaneous reset; softer sound with fewer high harmonics. Affects all outputs.689
Phase Input
cv
—
Phase modulation input. Sensitivity 90°/V, maximum offset ±450°. When patched, the Phase knob becomes a bipolar attenuator.689
Reset Input
trigger
—
Hard sync input. Instantaneously resets the oscillator; creates high harmonic content due to fast edges. Affects all outputs.689
TZFM Input
cv
—
Through-zero linear FM input. Normalised to +5 V internally. Bipolar: negative voltages cause the oscillator to run backwards. 0 V stops the VCO.689
V/Oct Input
cv
—
1 V/oct exponential pitch CV input. Standard 1 V/oct in audio mode; approximately 0.66 V/oct in low frequency mode.689
Outputs (5)
Core Output
audio
-5V to 5V
10 Vpp triangle wave directly from the VCO core, unaffected by the phase modulator. Runs at half the frequency of the fundamental output (one octave below); usable as a sub-octave signal.689
Even Output
audio
—
Saw wave at twice the fundamental frequency, containing only even harmonics (2nd, 4th, 6th...) that diminish with harmonic number.689
Full Output
audio
—
Mix of all three timbral channels (fundamental, even, odd), producing a full-spectrum signal containing all harmonics.689
Fundamental Output
audio
—
Sine wave output of the fundamental channel, with overtones suppressed. Amplitude controlled by the fundamental amplitude controller (balanced modulator). Runs at the base oscillation frequency.689
Odd Output
audio
—
Odd harmonics output, containing only odd harmonics excluding the fundamental (3rd, 5th, 7th...) that diminish with harmonic number.689
Parameters 9
Name
Type
Range
Behavior
AC Switch
switch
—
When enabled, AC-couples the TZFM input, rejecting DC offset and very low frequencies to prevent pitch shift during audio-rate FM. Also removes the normalised +5 V on the TZFM socket.689
Bias Switch
switch
—
Adds a +5 V offset to the TZFM signal, converting through-zero FM to normal linear FM. With no modulation patched, enabling bias doubles the frequency (one octave up). Default: off.689
Coarse Frequency
knob
22Hz – 22000Hz
Sets the oscillation frequency. In audio mode (fine centred, default TZFM): 22 Hz to 22 kHz. In low frequency mode with both knobs centred: 1 Hz. Total LF range: 2.8 mHz to 180 Hz.689
Exponential FM Polariser
knob
-1V/octave – 1V/octave
Sets the modulation depth and polarity for the exponential FM input. Centre (0) is no modulation; maximum is ±1 V/oct in audio mode, ±0.66 V/oct in low mode.689
Selects between low frequency (VCLFO) mode and audio frequency (VCO) mode. Affects the operating range and the V/oct sensitivity of the exponential FM inputs.689
Phase Knob
knob
-450degree – 450degree
When unpatched, manually adjusts phase. When patched, acts as a bipolar attenuator for the phase modulation signal at 90°/V sensitivity and ±450° maximum offset.689
Through-Zero FM Polariser
knob
—
Bipolar attenuator (polariser) for the TZFM input. At maximum with no patch and bias/AC off, the normalised +5 V runs the VCO in the selected range. When a cable is patched, controls modulation depth and polarity.689
V/Oct Trimmer
knob
—
Front-panel trim potentiometer for calibrating V/oct pitch tracking. Each module is individually calibrated at production; adjust only when out of tune. Calibrated by comparing 0 V vs +5 V pitch for a 5-octave interval.689