Ableton/Live/UG/31 Instrument Reference/09 Operator
- Operator combines Synthesis/Frequency Modulation with subtractive and additive synthesis. Four multi-waveform oscillators can modulate each other's frequencies, and it adds a filter, an LFO, global controls, and envelopes for each oscillator, the filter, the LFO and pitch.
- Garden notes: Ableton/Operator
- A central display sits between two sides of shell. The left shell has the four oscillators; the right has LFO, filter, pitch and global. Touching a shell control shows that section in the display, so levels and frequencies are reachable together while envelopes and waveforms sit in each display.
- The triangle at the top left folds the display away.
- Each oscillator either outputs audio or modulates another. Eleven algorithms, picked in the global display, set the connections; signal flows top to bottom in each icon. The algorithm can be mapped, automated and modulated.
- Beyond the usual FM sines, Operator offers other waveforms, two noises and a drawable partial editor. Ableton suggests exploring FM without the filter first, since many classic FM synths had none.
31.9.2.1 Built-in Waveforms
- From the Wave chooser: pure Sine, the usual first choice for FM; Sine 4 Bit and Sine 8 Bit for a C64-style sound; Saw D and Square D digital shapes for bass; resynthesized square, triangle and saw whose number (e.g. Square 6) is the harmonic count, with lower numbers mellower and less prone to aliasing; Noise Looped, a noise loop; and Noise White, true random noise.
31.9.2.2 User Waveforms
- User, or any built-in wave, can be edited by drawing harmonic amplitudes with the pencil;
Shift locks to one harmonic. The status bar shows harmonic number and amplitude. - Edit the first 16, 32 or 64 harmonics. Repeat extends them upward with a fade: low values are brighter, high values roll off more and favor the fundamental; Off truncates.
- The context menu limits drawing to even or odd harmonics and toggles Normalize, which keeps level constant; with it off, output can get very loud.
- Export as Ableton/File/.ams to Samples/Waveforms in the User Library; drop .ams files back on an oscillator, or into Simpler or Sampler. The Osc Preview's context menu copies waves between oscillators.
31.9.2.3 More Oscillator Parameters
- Coarse and Fine set frequency relative to the note. Fixed ignores note pitch and uses Freq times Multi, down to 0.1 Hz; only the timbre changes across keys, as for drums.
- Osc < Vel shifts frequency with velocity; Q quantizes the shift to whole ratios, otherwise it detunes into inharmonic tones.
- Amplitude comes from Level and the oscillator's envelope, scaled by Vel and Key.
- Phase, and R to restart the phase per note or run free.
- When modulating, the modulator's level and the frequency ratio set the result. An oscillator nothing modulates can modulate itself with Feedback.
31.9.2.4 Aliasing
- Digital synthesis aliases at high frequencies, and FM, with its many harmonics, does so readily; complex waves like Saw 32 more than sines. A little can be useful; too much makes high notes fold to unrelated pitches.
- Antialias mode, on by default for new patches, reduces it. Tone in the global section also tames it, sometimes like a low-pass filter. To hear aliasing, turn Tone up and play very high notes.
- The LFO runs up to audio rate, so it works almost like a fifth oscillator modulating the others' frequency.
- Dest. A buttons send it to each oscillator and the filter, with one amount; Dest. B adds another target with its own amount.
- Waveforms: classic shapes, S&H for random steps, and band-pass filtered Noise. The manual's tip: LFO noise is the key to FM hi-hats and snares.
- Rate with a Low, High or Sync range; Rate < Key makes it follow pitch; R retriggers.
- LFO Amount scales both destinations, modulated by Amt < Vel and the LFO's envelope.
- Seven envelopes: one per oscillator, plus filter, pitch and LFO. All can loop; filter and pitch envelopes have adjustable slopes.
- Oscillator envelopes have three rates and three levels: from Initial (often -inf dB) at the attack rate to Peak, at the decay rate to Sustain, and after note-off at the release rate back to silence. Drag breakpoints or nudge selected ones with arrow keys. Copy shapes between oscillators from the context menu.
- Slopes (filter, pitch) — positive moves fast then slow, negative slow then fast, zero linear.
- Loop — an envelope that reaches sustain while held restarts; Loop Time sets the return. Fast loops give effects you wouldn't expect from an envelope, and are the key to endless evolving FM sounds.
- Beat — restarts after the Repeat beat time without quantizing the first note. Sync — quantizes the first repeat to the nearest 16th so repeats follow the song; acts like Beat when stopped.
- Looped envelopes restart from their current level at the attack rate, so they don't click.
- Trigger — ignores note-off; good for percussion.
- Global Time scales all rates except Beat and Sync times; Time < Key speeds envelopes for higher notes; Time < Vel per envelope.
- The pitch envelope has Destination A–D and LFO buttons with an amount, an on switch in the shell, and a Dest. B target with Amt. B.
- Pitch and filter envelopes add End, the level after release.
- Tip from the manual: a looping pitch envelope routed only to the LFO acts as a second LFO on its rate, and the LFO's own looping envelope as a third on its depth.
- The filter shapes the oscillators' output; with classic waveforms Operator can work as a subtractive synth.
- Types: low-pass, high-pass, band-pass, notch and Morph, at 12 or 24 dB, with circuit models made with Cytomic:
- Clean — efficient, same as EQ Eight's filters; all types.
- OSR — state variable with a hard-clipping diode, from a rare British mono synth; all types.
- MS2 — Sallen-Key with soft clipping, from a famous Japanese semi-modular; low- and high-pass.
- SMP — a custom design between MS2 and PRD; low- and high-pass.
- PRD — a ladder with no resonance limiting, from an American dual-oscillator mono synth; low- and high-pass.
- Frequency and Resonance; non-Clean low-, high- and band-pass add Drive.
- Morph sweeps low-pass → band-pass → high-pass → notch → low-pass; its context menu snaps to each.
- The display switches between filter envelope and response curve; drag the curve to set cutoff and resonance.
- Cutoff modulation: Freq < Vel, Freq < Key, Envelope, and the LFO via Dest. A "FIL" or Dest. B. Play by Key in the Frequency context menu sets Freq < Key to 100% and cutoff to 466 Hz.
- Shaper curve with Shp. Drive and Dry/Wet after the filter; 0% wet bypasses it.
- Voices — up to 32; 6 to 12 is practical for CPU. At 1, overlapping notes play legato without retriggering envelopes, as for a flute.
- Volume in the shell; Pan in the display with Pan < Key and Pan < Rnd.
- MIDI routing: Velocity, Key, Aftertouch, Pitch Bend and Mod Wheel each reach two targets with amounts. Time < Key and the pitch bend range are fixed, though those sources can still take another target.
- Glide — polyphonic: new notes start at the last note's pitch and slide over Glide Time.
- Spread — two detuned voices per note panned left and right for chorus. It is read at note-on, so a sequence can make only some notes stereo. Costs CPU.
- Transpose — global.
- Turn off unused features, especially the filter and LFO, and keep voices at 6 to 12. Use Spread sparingly, and switch off Interpolation and Antialias if needed.
- Turning off oscillators doesn't save CPU.
- Operator comes from a love of hardware FM synths such as the Yamaha SY77, the Yamaha TX81Z and the NED Synclavier II.
- John Chowning first explored FM musically in the mid-1960s. In 1973 he and Stanford began working with Yamaha, which led to the DX7.
- Every parameter, grouped by where it sits; the Info View also explains any control under the mouse.
31.9.10.1 Global Shell and Display
- Time — scales all envelope rates. Tone — high-frequency content; brighter means more aliasing risk. Volume. Algorithm — oscillator connections.
- Voices — oldest notes are cut when exceeded. Retrigger (R) — retrigger a playing note instead of adding a voice.
- Interpolation — off sounds rougher, especially noise, and saves CPU. Antialias — off saves CPU.
- Time < Key — faster envelopes for higher notes. PB Range.
- Pan, Pan < Key (low notes left, high right, as for pianos), Pan < Random.
31.9.10.2 Modulation Targets
- For MIDI routings, the LFO's Dest. B and the pitch envelope's Dest. B: Off; OSC Volume A–D; OSC Crossfade A/C and B/D; OSC Feedback (only unmodulated oscillators); OSC Fixed Frequency; FM Drive (level of all modulators); Filter Frequency; Filter Q (Legacy); Filter Res; Filter Morph; Filter Drive (not with Morph); Filter Envelope Amount; Shaper Drive; LFO Rate; LFO Amount; Pitch Envelope Amount; Volume; Panorama; Tone; Time.
31.9.10.3 Pitch Shell and Display
- Pitch Envelope On — off saves CPU. Pitch Env — ±100%; 100% follows the envelope's levels, negative inverts.
- Spread, Transpose (affects playing notes), Glide (G) and Glide Time; legato glides don't retrigger envelopes.
- Destination A–D and LFO switches with Amount A; Destination B with Amount B.
31.9.10.4 Filter Shell and Display
- Filter On (off saves CPU), Filter Type, Circuit Type, Freq, Res (resonance for low- and high-pass, width for band-pass and notch).
- Freq < Vel; Freq < Key, where 100% doubles cutoff per octave around C3; Envelope, where 100% can shift about nine octaves.
- Flt. Drive, Morph, Shaper, Shp. Drive, Dry/Wet.
31.9.10.5 LFO Shell and Display
- LFO On (off saves CPU). Waveform — all band-limited to avoid clicks.
- Range — Low covers 50 seconds to 30 Hz, Hi 8 Hz to 12 kHz, or Sync to tempo.
- R, Rate, Amount, Destination A–D and FIL with Amount A, Destination B with Amount B.
- Rate < Key — at 100% the LFO doubles per octave like an oscillator. Amt < Vel.
31.9.10.6 Oscillators A-D Shell and Display
- Osc On. Coarse — whole-number ratios for harmonic relationships. Fine — fractions for inharmonic ones.
- Fixed, Freq and Multi — a constant frequency, Freq × Multi in Hz.
- Level — on a modulator, higher levels usually mean brighter or noisier sounds.
- Envelope/Oscillator display switches; 16/32/64 partials; Wave; Repeat.
- Feedback — self-modulation of an unmodulated oscillator, also shaped by its level and envelope.
- Phase (one full cycle), R.
- Osc < Vel with Q; Vel and Key for level, centered on C3. Velocity on modulators makes timbre follow touch.
31.9.10.7 Envelope Display
- Attack — linear on oscillator envelopes, shapeable on filter and pitch. Decay — exponential on oscillators. Release — from the current level at note-off to End, or to -inf dB on oscillators.
- Initial, Peak, Sustain, and End (LFO, filter and pitch only).
- Loop mode — Loop, Beat, Sync or Trigger. Repeat — beat time for Beat and Sync. Loop Time — return from sustain to initial.
- Time < Vel — scales segments, not Beat or Sync times.
- A.Slope, D.Slope, R.Slope — filter and pitch envelopes.
31.9.10.8 Context Menu Options for Operator
- Copy parameters between oscillators; set all envelope levels to maximum, minimum or middle; harmonics editor options (even or odd, Normalize, export .ams); Play By Key; and Enable Per-Note Pitch Bend, on by default.
