Bass drum
62.5 Hz ladder resonator
V78 Preset-rhythm circuit instrument
Voltage 78. The whole machine matters.
A preset-rhythm instrument modelled from the Roland CR-78’s service data and measured behaviour. The voice circuits, shared sources, fixed kit balance, cancel groups and master accent VCA are rebuilt as one connected system—not a folder of isolated recordings.
Names and circuit familiesSee the complete voice set
Balance, accent, add, cancelFollow the machine laws
- Fourteen voice circuits, fifteen trigger choices
- Factory frequencies, decays and relative levels
- One shared noise source across related voices
- Continuous master-VCA accent, not velocity layers
- No recorded one-shots or sample library
01 The voice set
Fourteen circuits. Fifteen ways in.
The guiro has separate high- and low-rate triggers, so its one circuit supplies two playable choices. Every other abbreviation maps to a distinct synthesized part.
Snare drum
340 Hz shell · gated noise
Rim shot
1.48 kHz tuned tank
Claves
2.63 kHz tuned tank
Cowbell
555 / 800 Hz keyed pair
High bongo
600 Hz ladder resonator
Low bongo
400 Hz ladder resonator
Low conga
208 Hz ladder resonator
Cymbal
Shared noise · tuned gate
Hi-hat
Shared noise · 60 ms decay
Maracas
Shared noise · 20 ms decay
Tambourine
Add voice · ringing gate
Guiro high / low
125 / 77 Hz step-length scrape
Metal beat
Three-oscillator metallic bank
Calibrated as a kit: voice levels follow the factory Vpp table rather than fifteen independent volume knobs. The rim shot is deliberately twice the bass drum’s factory peak voltage; that relationship is part of the instrument.
02 Circuit signatures
Preset-rhythm character. Generated in motion.
The most revealing parts are behaviours a fixed recording cannot follow: the guiro changes length with the sequencer step, the add voices bypass Balance, and the metallic and noise sources keep moving between hits.
A three-section RC phase-shift ladder rings at the factory setpoint—a different topology and character from Voltage 80’s bridged-T kick.
Three free-running oscillators feed a tuned swing-gate output whose measured peak is dominated by the resonant tank.
The scrape follows the sequencer step, growing longer as tempo slows instead of replaying one fixed-length recording.
Current release status
The Voltage 78 engine is implemented and its conformance and factory-calibration suites run behind a release feature. It is not yet exposed in the current pre-release plug-in binary.
03 The real control surface
Balance the machine. Do not dismantle it.
The original architecture has no per-voice level or tone controls. Its identity comes from fixed calibration and a small set of controls acting across the whole circuit.
- Balance. Crossfades the tonal and noise buses around a centre detent.
- Accent. Sets the continuous per-step lift at the master VCA.
- Add levels. Tambourine, guiro and metal beat enter after Balance through their own levels.
- Master level. Controls the complete machine output.
- Cymbal + hi-hat. One shared cancel group; metal beat continues independently.
- Bass drum. Removes the bass-drum trigger group.
- Snare drum. Removes the snare trigger group.
- Cowbell + claves. The two parts share one hardware cancel line.
04 One connected rhythm machine
Relationships are part of the sound.
Noise is shared.
Cymbal, hi-hat and maracas draw from one source and one shared level trim, so their variation remains related rather than independently random.
Accent happens after the voices.
The per-step control voltage lifts the master VCA. It does not swap samples or reshape each voice’s trigger as Voltage 80 does.
Add voices sit outside Balance.
Tambourine, guiro and metal beat join after the tonal/noise crossfade, preserving the hardware routing when Balance moves.
05 Voltage 78 FAQ
Three direct answers.
Is Voltage 78 a sample-based rhythm machine?
No. Voltage 78 synthesizes its voices from resonators, shared noise, keyed oscillators, swing-type gates and envelopes. The voice balance is calibrated from the Roland CR-78 factory adjustment table.
Why is there no level and tone control for every voice?
The hardware did not have them. Voltage 78 preserves its actual voicing surface: Balance, Accent, three add-voice levels and four cancel groups, with voice levels fixed by factory calibration.
Is Voltage 78 available in the current pre-release plug-in?
Not yet. Its engine is built and tested behind the Voltage 78 release gate, but it is not exposed in the current pre-release binary. It remains part of the planned complete Voltage Drums line-up.
Trademark notice. The Roland CR-78 is referenced only to identify the hardware studied and measured. Roland and CR-78 are trademarks of Roland Corporation. Voltage 78 and Voltage Drums are independent products, not affiliated with or endorsed by Roland.
06 The family
Different decade. Different circuit logic.
Compare Voltage 78’s preset-rhythm architecture with the sixteen-voice Voltage 80 instrument.
Sixteen voices · playable nowExplore Voltage 80