Complex digital oscillator with unison detune, programmable 3x4 modulation matrix mixer and external input. Intricate arrangements of phase distortion, thru-zero frequency modulation, and complex oscillation are instantly morphable and recallable through a voltage-controlled preset manager. Suitable for genre-targeted sequenced basslines, synthesis of stone, glass, and steel tones, and simulation of the acoustic properties of industrial machinery.


The Hertz Donut Mark III’s main oscillator shapes its timbre by distorting the phase of a waveform lookup ramp, offering a linear growth of brass overtones from a simple sine wave whilst performing with exceptional clarity under heavy frequency modulation. The simulated resonance peak familiar to enthusiasts of phase distortion is also present and continuously controllable. The beloved “fractal” distortion from previous iterations of Hertz Donut is simultaneously available. The three waveform parameters operate in a modeless timbre space fully morphable under preset and shared manual/CV control, exhibiting stunning spectral evolutions that are intensified through the module’s internal modulation bus. The fold knob is assignable to control one of the three parameters at a time, with the CV input also assignable to any of the three.


Two sinusoidal modulation operators are mixed to four modulation destinations with an external audio input. The operators may be locked to several precise frequency ratios of the main oscillator, or set to be otherwise subordinate. The three sources may modulate each other’s frequencies, or the amount of phase or fractal distortion. A plethora of control voltage inputs allow full control of the patch, reacting within a +/- 10V range. The first operator has a calibrated 1v/oct control voltage input and fine tune control, for use as an independent oscillator augmented by the modulation bus. The modulation mix is placed under the influence of a master control, so that a single knob and CV input control the degree of modulation in the entire module. Each sound that you design will have a unique and intense behavior of this modulation control.


The preset manager stores 8 entire panel/menu states for instant recall under manual or voltage control. The control can also cause the creation of elegantly randomized preset data. The preset manager can be placed into a morphing mode where it assumes control of the various parameters, smoothly fading between entire panel states and generating very complicated sounds that are not easily described.


The unison detune function mixes in a nearly identical copy of the sound with slightly offset frequency, or optionally in octave or fifth intervals. The Hertz Donut operates at 96khz for a minimum of sampling byproducts, able to consistently and competently generate ornate digital beauty and jagged swaths of sonic mayhem. The auxiliary output presents the output of one or both modulation operators, also with optional unison applied. The nearby mix output is an analog sum of the Main and Aux outputs, facilitating parallel FM algorithm construction. 17 HP panel size. Perfect, genuine, complete, crystalline, pure.


Main oscillator with resonant, phase, and fractal distortions (cv and manual knob destinations selectable)
8 octave tuned CV response (1v/octave)
2x sinusoidal modulation operators with frequency interval lock or free operation
External thru-zero FM input
4x3 modulation matrix mixer with master amount control
128x32 OLED display providing realtime note, frequency, and modulation information, as well as menu access to deep settings
All parameters may be placed under control of morphing preset manager, with 8 onboard presets (nonvolatile)
96 kHz sampling rate