Dr. John Chowning first described FM Synthesis technique in 1967. Since that time, no analog quadrature oscillator with through-zero capability and dynamic linear FM control has been commercially available... until now!

Cyndustries is proud to announce a major breakthrough in analog VCO design, the amazing Zeroscillator.

Liquid Smooth Analog Design

The Zeroscillator is a full-featured electronic-music-quality analog VCO capable of linear frequency modulation through zero hertz and into negative frequencies. This makes it capable of the FM Synthesis stuff, wild and crazy sounds simply not available from traditional VCOs, and timbres not available from digital FM synthesizers. Of course, Zeroscillators also make insane LFOs!

Traditional FM Synthesis oscillator implementations, such as the DX-7, are sine wave only. The Zeroscillator also makes available sawtooth, reverse saw, triangle, pulse (with PWM), and a special set of four quadrature outputs capable of unique bi-phase wave morphing, (more on that later).

Look Ma'...  No Aliasing!

FM sounds take on their vibrant life when the amount of modulation is varied dynamically. In the analog world, this requires a special VCA to regulate the depth of frequency modulation, (often called the "modulation index"). Since this is required almost universally for Linear FM patches, the Zeroscillator has this VCA built-in. We decided however, to take this feature one extra step beyond and provide you with a four-quadrant multiplier instead of a traditional two-quadrant VCA to expand your modulation possibilities into the unexplored. The output of this multiplier is available at the panel, so you get a free ring-mod function and an interesting pick-off point for self-modulation patches called Mod Out.

In addition to it's precision 10-turn tuning knob, the Zeroscillator has 1V/octave plus attenuated exponential inputs and can behave just like the VCOs you're used to. You are not forced into any specific modality and are free to use all or any subset of its 7 different modulations:

1-Exponential FM
2-Linear Through-Zero FM
3-Linear FM Dynamic Depth Modulation
4-Bi-Phasic Waveform Morphing in Quadrature
5-Pulse Width Modulation
6-Variable Sync (from none to hard synch)
7-Time Reversal

The through-zero capability may be switched off which bars the oscillator from reaching into the negative frequency netherworld. If the linear modulation goes negative, the oscillator simply stops, restarting when the modulation returns to positive territory. This results in another class of sounds and is also very interesting and rhythmic when used at LFO rates.

Now back to the Quadrature Outputs with Bi-phase Wave Morphing. These four outputs present the oscillator waveform at four different relative phases separated by 90 degrees (0, 90, 180, 270). If the 0 and 90 degree outputs are presented to the left and right speakers respectively, a definite stereo spread effect is obtained, and when the oscillator beats with its modulator, harmonic characteristics shift back and forth across the stereo image. This effect is unique to the Zeroscillator.

Quadrature Waveform
Voltage Controlled Wave Morphing in Four Phase Quadrature

At LFO rates, the quadrature outputs can be used to control quad panning or create circular illusions. Remember, when the Zeroscillator is heavily FM'ed, the waveforms fold back on themselves and create patterns that look nothing like the waveforms on the label.

This ain't your Daddy's oscillator!

You can also morph the waveform coming from the quadrature outputs from triangle to sine to square! The 0, 180 pair and the 90, 270 pair have separate morphers which can move in tandem or opposition to each other. The morph is not simply a waveform crossfade, but a true morph which creates all the in-between waveforms in its travel and it can even be modulated at full audio rates! The morph is also constant-power which means the perceived loudness does not change as the harmonic content is being radically altered. With the morph feature, youll find yourself not needing a filter in a great many patches.

We even threw in the kitchen, (Sync that is)... The Zeroscillator has Variable Synchronization from, "no sync at all... "to Totally Hard Sync". You just dial-in the right amount for your particular patch, (for classic FM type synthesis, you'll be glad you have this control on a dedicated knob).

Finally, there is the mysterious "Time Reversal" Input, (which is actually what occurs when the oscillator passes into negative frequencies). Your external signal here forces the waveform to reverse its direction of travel as seen on an oscilloscope. The resulting effect is most similar to hard sync, but a completely separate circuit, and they both may be used together.

Traditionally, a VCO was something that gave you a tone, a starting place from which you built your sound with other modules. The Zeroscillator however, is practically a synthesizer unto itself.

$ 1195 US
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Zeroscillator AUDIO DEMOS by Mark Barton

The following sound samples were created using a single Zeroscillator (the carrier) being modulated by a typical VCO (the modulator) and/or combinations of LFOs and Envelope Generators. With the exception of a VCA and a tiny bit of reverb in some cases, there is no other processing of any kind in these recordings of the Zeroscillator output. Specifically, no filters were utilized. Some patch ideas HERE.

Scifi (mp3) - Envelope Generator controls modulator frequency (ordinary VCO) which is patched to Zeroscillator Linear FM Input. An LFO is also patched into the Zeroscillator Exponential FM Input. The Sine Wave Output is heard.
FM Percussion (mp3) - Bell Tones, Classic Linear FM Synthesis patch with FM Modulation Index dynamically modulated by an envelope generator.
Sequence (mp3) - The Row-A Output of a Sequencer modulates Exponential CV Input of Modulator VCO, while Row-B Output modulates Exponential FM Input of the Zeroscillator, (Carrier). Stage #1 Gate Output of Sequencer triggers an Envelope Generator which is patched to Zeroscillator Morph CV Input resulting in accents in timbre on first note. FM fades in at beginning and out at end. We hear the Morph Output as various knobs are twiddled while the sequence plays.
BluesMix (mp3) - Overdubbing three passes of Zeroscillator voices with no filters!
Wicked (mp3) - Three crazy Zeroscillators throwing a fit!
Stereo VZO (mp3) - Run for the headphones! Get comfortable and meditate on this one for 3 minutes of stereo heaven from a single Zeroscillator...
Zo Video - Video of the Zeroscillator
Zo3D - 3D rendering of the Zeroscillator
Zeroscillator MOTM Version Zeroscillator Blacet Version ZeroscillatorDot Com Version Zeroscillator Euro-Rack Version Zeroscillator Modcan Version


Further Reading on FM Synthesis:

The links below are generally specific to computer realized types of FM synthesis, which is OK when you consider that there has never been an analog FM equivalent available before...

Simply convert the word 'digital' to the word 'analog' in your mind as you read, which can actually make for pretty funny and rather dated reading now when you see statements in print such as:

"FM synthesis, even with its reputation for being cold" or

"for musically useful "real" FM synthesis the frequency and amplitude relations have to be extremely accurate and this cannot be obtained with analog circuits. "This is (and will probably remain) a digital domain"

Guess they just haven't yet had the pleasure of trying an analog Zeroscillator!

1. Digital Sound Synthesis Using FM

2. Principals of Audio-Rate Frequency Modulation

3. Basic Frequency Modulation Synthesis Technique

4. FM Article download from MusicTech magazine

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