Rossum Electro-Music Trident is a fully analog Eurorack module housing three precision VCOs, designed by Dave Rossum as a Multi-Synchronic Oscillator Ensemble. Each oscillator functions as a standalone VCO with 1V/oct tracking, but the module's defining behavior emerges in synchronous operation: a Carrier oscillator combined with two Modulation Oscillators form an internal cross-modulation architecture that no conventional triple-VCO arrangement can replicate.
Zing — Timbral Modulation Without Inharmonic Sidebands
Zing is Rossum's proprietary mechanism for amplitude-modulating each of the Carrier's outputs using the Modulation Oscillators. Mathematically it behaves like ring modulation, but with a critical distinction: when oscillator Sync is enabled, the inharmonic sum and difference sidebands characteristic of standard ring mod lock into purely harmonic overtone spectra. These shift dynamically with the frequency, symmetry, and waveshape of the modulating oscillator. Crucially, every change in the Mod Oscillator parameters produces a different effect on each of the three Carrier outputs (triangle, sawtooth, pulse) independently. Zing Level has its own CV input with attenuation on each Modulation Oscillator, enabling full CV-driven timbral animation without external VCAs in the signal path.
Track and Sync as Harmonic Relationship Controls
The Track switch on each Modulation Oscillator determines whether its frequency follows the Carrier's 1V/oct input. With Track on, the harmonic ratio between oscillators remains constant across the keyboard — timbre stays fixed as pitch transposes. With Track off, the Mod Oscillator frequencies are absolute, causing the overtone structure to shift relative to the Carrier as pitch changes. This distinction is fundamental to patch design: the same Zing and Symmetry settings produce completely different timbral behavior depending on Track state. Modulation Oscillator 2 additionally includes a Phase parameter with its own CV input — not available on Mod Oscillator 1 — enabling phase modulation of the Carrier outputs for further spectral shaping.
KEY FEATURES
- Three precision analog VCOs, range 20 Hz–20 kHz (controlled), 0.01 Hz–25 kHz (modulated)
- Carrier: simultaneous triangle, sawtooth, and pulse outputs; exponential and linear FM, PWM, hard sync input
- Mod Oscillator 1: selectable waveform, Symmetry CV, Zing Level CV, Sync/Track on/off
- Mod Oscillator 2: as above + Phase and Phase CV (not available on Mod 1)
- Zing Modulation: analog timbral modulation producing harmonic spectra when Sync is engaged
- Independent Sync and Track switches per Modulation Oscillator
- All CV inputs: attenuverted, 100 kΩ impedance
- Thick aluminum panel, solid aluminum knobs, reverse polarity protection
TECHNICAL SPECIFICATIONS
- Format: Eurorack
- Width: 30 HP
- Depth: 25 mm
- Power: +12V 250 mA / -12V 225 mA
- Reverse polarity protection: yes
- Frequency range (controlled): 20 Hz–20 kHz
- Frequency range (modulated): 0.01 Hz–25 kHz
- Carrier Sync input: 3.5V rising edge threshold, 100 kΩ impedance
- Carrier audio outputs: 3x 3.5 mm mono jack, 1 kΩ impedance
- Mod Oscillator 1 and 2 audio outputs: 1x 3.5 mm mono jack each
- CV inputs: 3.5 mm mono, 100 kΩ impedance (linear FM min. 80 kΩ)
