Three Analog Oscillators, One Synchronous Ensemble
The latest brainchild of synth pioneer Dave Rossum, TRITON is a 100% analog, triple oscillator module that opens up a universe of dynamic timbral textures.
At its most basic level, TRITON is three precision audio VCOs, each sporting a unique variety of control voltage inputs. The main or "Carrier" oscillator provides its three waveforms simultaneously. The two Modulation Oscillators each have a single output and a waveform selector.
The Modulation Oscillators also have a voltage controlled Symmetry parameter which varies the duty cycle of the triangle wave output from sawtooth to triangle back to time reversed sawtooth, and also varies the sawtooth output to have an upward or downward kink in the middle, as well as controlling pulse width when the pulse waveform is selected.
And while each oscillator can be used independently if desired, it's when they're combined into a synchronous ensemble that the real sonic magic happens. That magic is what we call Zing Modulation. Each of the Modulation Oscillators can modulate each of the Carrier outputs in an amount controlled by the Zing parameter.
Zing Modulation is mathematically akin to ring modulation, but due to the synchronization of the oscillators, the aharmonic sum and difference sidetones of ring modulation transform into complex but purely harmonic overtone spectra, which vary dynamically and dramatically with the frequency and waveshape modulations of the modulation oscillators. Whether you take advantage of TRITON's unique synchronous modulation capabilities or just treat it as three superb, wide-range analog oscillators, TRITON offers a vast variety of dramatic sonic textures.
Specifications
| Oscillators | 3 |
| Coarse frequency range | 20 Hz–20 kHz |
| Modulated frequency range | 0.01 Hz–25 kHz |
| Pitch input | 1V/Octave per oscillator |
| Waveforms | triangle · sawtooth · pulse (simultaneous) |
| Modulation | exponential & linear FM, PWM |
| Sync | hard sync input |
| Waveforms | selectable triangle · sawtooth · pulse |
| Frequency modulation | exponential |
| Symmetry | variable + symmetry modulation |
| Zing | variable level + level modulation |
| Phase (Mod Osc 2) | variable + phase modulation |
| Sync & track | independently selectable to Carrier |
| Width | 30 HP |
| Depth | 25 mm |
| Power | ±12 V · reverse-polarity protected |
| Current draw | 290 mA / 270 mA |
See It in Action
Introduction & Overview
Sound demonstration
Show 3 more videos...
In Depth (Ben "DivKid" Wilson)
10 Sounds (Andras Eichstaedt)
First Patch (DivKid)
How Zing Modulation Works
TRITON's signature timbres come from synchronizing three oscillators and letting the Modulation Oscillators reshape the Carrier, a process Rossum calls Zing Modulation.
Three oscillators, three roles. The main Carrier oscillator provides its triangle, sawtooth and pulse waveforms simultaneously. Each of the two Modulation Oscillators has a single output and a waveform selector, plus a voltage-controlled Symmetry parameter that sweeps the triangle output from sawtooth to triangle to time-reversed sawtooth, bends the sawtooth with an upward or downward kink, and controls pulse width when the pulse waveform is selected.
Zing Modulation. Each Modulation Oscillator can modulate each of the Carrier outputs by an amount set with the Zing parameter. Zing Modulation is mathematically akin to ring modulation, but because the oscillators are synchronized, the aharmonic sum and difference sidetones of ring modulation transform into complex but purely harmonic overtone spectra, varying dynamically with the frequency and waveshape modulations of the Modulation Oscillators. Every change to a Modulation Oscillator's Frequency, Symmetry, Waveshape, Zing, or (on Modulation Oscillator 2) Phase affects the timbre of each of the three Carrier outputs differently.
Tracking the Carrier. When the Modulation Oscillators are set to track the Carrier, the waveshape stays constant as the Carrier frequency changes, so the overtone structure is determined by the Modulation Oscillator settings and CV modulations. If instead they do not track the Carrier, some of the overtone structure varies relative to the Carrier frequency.
"Whether you take advantage of TRITON's unique synchronous modulation capabilities, or just treat it as three superb, wide-range analog oscillators, TRITON offers a vast variety of dramatic sonic textures."
Dave's TRITON Deep Dive
Dave Rossum's original write-up on what inspired TRITON — the math behind Zing Modulation and the engineering challenge of voltage-controlled Symmetry — recovered in full, with all eight oscilloscope photographs.
Since we launched Rossum Electro and produced our first module (Evolution), folks have been bugging me to build an analog VCO. In their day, the E-mu Modular VCOs were the most stable and had widest range of any of that era. But I waited for inspiration to strike, and it did, twice!
So what is “Zing Modulation” anyway? In thinking about what makes an interesting timbre, I have always felt ring modulation (actually, “four quadrant multiplication”) held a prime spot, but it’s limited in usefulness because it produces frequencies that are not harmonically related to its inputs. This is due to the trigonometric identity:
2 x sin(A) x cos(B) = sin(A + B) + sin(A – B)
where A and B are frequency components of the ring modulator inputs.
But I realized that if the two inputs could be forced to be periodic with the same frequency, this limitation would disappear. To understand why, just realize that there is no “memory” in a ring modulator – if you start over from the same spot and give it the same waveforms, it will produce the same output every time. So the output of two inputs that have the same period must itself be periodic at that same frequency, which means all its frequency components must be harmonics of that frequency. And it’s fairly easy to arrange two oscillators to be precisely periodic – it’s called hard sync*. Bingo!
But because of that crazy trigonometric identity, there are going to be zillions of harmonic components, all adding together in weird combinations of phases, and these will vary in interesting ways depending on the exact details of the incoming waveshapes. Below are some examples of the bizarre waveshapes coming out of TRITON. The yellow waveshape is the carrier oscillator with Zing modulation; the green is the original carrier waveshape. The blue and red traces are the modulation oscillators.
The second inspiration was to build a VCO that would provide interesting yet precise control of the waveshapes. The circuitry underlying TRITON’s symmetry control was remarkably challenging. Varying the symmetry of a triangle wave from sawtooth, through triangle, to inverted sawtooth has been done many times before, but doing so in a fully analog, voltage controlled manner that has absolutely no effect on the underlying frequency is extremely challenging. Add to that challenge the requirement for the waveforms to be visually perfect up to 20kHz – now that would be fun (i.e. really hard)! I had to throw away an entire prototyped design because it wasn’t quite accurate enough at the highest frequencies. The final circuit is the only time I’ve ever had to specify a capacitor as small as 0.5pF to get the precise results I wanted. Here are some of the pure waveshape ‘scope photos. The top photo is the shapes at about 250 Hz, below it are the shapes at about 20kHz!
Finally, I realized that I’ve never seen anybody play with the phase relationship between hard synced oscillators. Combining that with Zing modulation gives even more voltage controlled timbral variation. These waveforms differ only by the phase of the MOD 2 oscillator!
* I’m pretty sure I was the person who first coined the term “hard sync.” I didn’t invent hard sync; I think that honor goes to Serge Tcherepnin. When I heard about it and how great it sounded, I immediately implemented it. But E-mu modular VCOs already had one form of sync, so we needed another name to distinguish the two. Hence “hard sync” and “soft sync”.
Manuals & Guides
Frequently Asked Questions
What is Triton?
Triton (formerly Trident) is a 100% analog triple oscillator module for Eurorack. At its core it is three precision audio VCOs. Combined into a synchronous ensemble through its Zing Modulation system, the three oscillators interact to produce complex harmonic overtone spectra beyond what a standard complex oscillator reaches.
Was Triton previously called Trident?
Yes. Triton was renamed from Trident. Older documentation and forum posts call it Trident. The module is identical under either name. No hardware or firmware changes came with the rename.
How are Triton's three oscillators different from each other?
Triton has one Carrier oscillator and two Modulation Oscillators, built differently. The Carrier provides simultaneous triangle, sawtooth and pulse outputs. Each Modulation Oscillator has a single output with a waveform selector.
- Carrier: simultaneous triangle/sawtooth/pulse outputs, exponential and linear FM, pulse-width control and PWM, and a hard-sync input.
- Modulation Oscillator 1: selectable waveform, exponential FM, variable Symmetry (with modulation), and variable Zing level (with modulation).
- Modulation Oscillator 2: everything Mod Osc 1 has, plus variable Phase and phase modulation.
Both Modulation Oscillators can independently sync to and track the Carrier. That is what turns ring-modulation-style Zing into purely harmonic overtones.
What is Triton's frequency range?
Each of Triton's three oscillators has a coarse range of 20 Hz to 20 kHz and an extended range of 0.01 Hz to 25 kHz under CV. Every oscillator has its own 1V/oct input for accurate pitch tracking. That span lets each oscillator work as an audio VCO or, at the low end, as a slow control-voltage source. Dave Rossum designed the Symmetry circuitry so the waveforms stay clean all the way up to 20 kHz, which is why Triton holds precise Zing timbres across its full audio range.
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The Three Oscillators
Does Triton have linear FM as well as exponential FM?
Yes, but only on the Carrier oscillator. The Carrier accepts both attenuverted exponential FM and attenuated linear FM through separate inputs. Use exponential FM for musical, pitch-tracking effects, or linear FM for cleaner, more predictable modulation. The two Modulation Oscillators provide exponential FM only, plus their 1V/oct inputs. If you need linear FM, patch it into the Carrier. The linear FM input is a minimum 80 kΩ, while the other CV inputs are 100 kΩ.
Zing Modulation
What is Zing Modulation?
Zing Modulation is mathematically close to ring modulation, with one key difference. When the modulation oscillators sync to the carrier, the normally inharmonic sidebands of ring modulation snap into complex but purely harmonic overtone spectra. You get the richness of ring modulation without the atonal, clanging artifacts. The Zing parameter sets the modulation depth. Each change in a modulation oscillator's frequency, symmetry, waveshape or phase affects all three carrier outputs differently and at once.
What does the Symmetry control do?
Symmetry varies the duty cycle of a modulation oscillator's output. On a triangle it morphs from sawtooth through triangle to reversed sawtooth. On a sawtooth it adds an upward or downward kink. On a pulse it controls pulse width. Because Symmetry feeds Zing Modulation, small changes produce very different harmonic structures at the carrier outputs.
What does the Phase control on Modulation Oscillator 2 do?
Modulation Oscillator 2 has a variable Phase control and a phase-modulation CV input, which Modulation Oscillator 1 does not. Phase adjusts the relationship between the hard-synced oscillators, adding another axis of voltage-controlled timbral variation on top of Zing. Dave Rossum called this a deliberate, unusual choice: combining the phase relationship between hard-synced oscillators with Zing yields waveforms that differ dramatically based only on Mod Osc 2's phase setting. Because Phase is voltage-controllable, you can modulate it from an envelope or LFO for evolving harmonic movement.
How do I get the most musical results from Zing Modulation?
Start with both modulation oscillators synced and tracking the carrier, then introduce Zing slowly from one oscillator at a time. With tracking on, the harmonic overtone structure stays constant as you play different notes. The timbre becomes a preset you can play chromatically. Without tracking, the harmonics shift relative to the carrier frequency, which is also useful but less predictable.
Configuration & Playing
Can the three oscillators be used independently, and how do I create chords?
Yes. Each oscillator has its own 1V/Oct input and works as a standalone VCO with a wide frequency range. To run the three independently for chords, turn TRACK off, turn SYNC off and turn ZING fully down, then send a separate V/Oct to each oscillator (sawtooth waves work well). Chords can sound slightly detuned and may need occasional retuning. Triton's real strength is the three oscillators working together through Zing.
Do the oscillators track well?
Yes. The tuning is stable and the fine-tune control has high resolution. Precise tuning matters because Zing Modulation produces harmonically related overtones only when the oscillators are precisely tuned relative to each other.
How do I calibrate the oscillators?
Triton has trim pots on the PCB for calibrating each oscillator's V/Oct tracking. The general procedure uses a precision voltage source and a tuner to adjust each oscillator's tracking trim. A community calibration guide exists (search ModWiggler). If you are not comfortable with PCB-level adjustment, contact support and Rossum can handle it as a repair.
Inputs & Outputs
What inputs and outputs does Triton have?
Triton has a full set of 3.5 mm mono jacks across its three oscillators. The Carrier offers a hard-sync input, 1V/oct, exponential and linear FM, pulse-width-modulation CV, and three simultaneous audio outputs (triangle, sawtooth, pulse). Each Modulation Oscillator adds its own CV inputs plus one output.
- Carrier: Sync In (3.5V rising-edge threshold), 1V/oct, attenuverted exponential FM, attenuated linear FM (min 80 kΩ), attenuverted PWM, and 3 audio outputs (1 kΩ).
- Modulation Oscillator 1: 1V/oct, attenuverted exponential FM, attenuverted Symmetry-mod CV, attenuverted Zing-level CV, and 1 audio output.
- Modulation Oscillator 2: the same as Mod Osc 1 plus an attenuverted Phase-modulation CV input, and 1 audio output.
Most CV inputs are 100 kΩ.
Specifications & Power
How wide is Triton and will it fit in my case?
Triton is 30 HP wide and 25 mm deep. At 30 HP it is the widest module in the Rossum lineup. Make sure your case has the horizontal space. Its 25 mm depth is skiff-friendly.
What are Triton's power requirements?
Triton draws 290 mA on +12V and 270 mA on -12V. It is a high-current analog module. Check that your power supply can handle the draw, especially on the -12V rail, where many supplies are weaker. It uses a standard 16-pin Doepfer-style connector and is reverse-polarity protected.
What's included in the box with Triton?
In the box you get a 16-pin Doepfer-style power cable, 4 M3 screws, 4 M2.5 screws, 4 nylon washers and a Quickstart Guide.
Troubleshooting
Why can I hear the other oscillators from OSC 1's output even with Zing turned down?
A small amount of bleed from the modulation oscillators into the carrier outputs is normal at very low Zing settings. It is inherent to the analog circuit topology and is usually masked by the carrier signal at performance levels. If the bleed is prominent with Zing fully counterclockwise, contact support with your serial number, as it may indicate a calibration issue.
The carrier oscillator pitch drifts or becomes unstable over time.
Some drift when the module is first powered on is normal for analog oscillators. Allow 10-15 minutes for thermal stabilization. If drift keeps worsening or becomes severe enough to affect tuning during a session, the oscillator may need recalibration or repair. Contact support with your serial number.
