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Master Class: Ableton Operator

April 4, 2017

Ableton Operator provides a unique hybrid approach to additive, subtractive, and FM synthesis (somewhat like the Synclavier did) and is one of the most deceptively powerful softsynths available.

Even so, many musicians shy away from using it fully because FM synthesis remains opaque despite its prevalence for more than 30 years. Fortunately, Operator’s clean interface and streamlined tools make it the perfect synth for getting started with both FM and additive synthesis, so you can start whipping up your own creations with it.


The term operator was first popularized with Yamaha’s groundbreaking DX series of instruments, where it was generally defined as being an oscillator with its own dedicated amplitude envelope. In modern FM synthesis, configurations of multiple operators are called algorithms. In a nutshell, algorithms govern the interaction between a set of operators, with each algorithm functioning as its own synthesis structure. If you’re a modular-synth fan, think of them as preconfigured cable routings. That is, each type offers different features that make it well-suited to specific applications.

Fig. 1

Because Operator’s features include multiple synthesis options, the easiest way to get started is with the all-carrier algorithm (see Figure 1). While there is no FM functionality here, it’s fantastic for both analog-style subtractive synthesis and more exotic additive approaches, which should also appeal to fans of vector synthesis. In this algorithm, Operator functions as a four-oscillator synth with individual volume envelopes for each oscillator, followed by a modeled analog filter. (Note that the filter is at the end of the chain, after each oscillator’s amp envelope. We’ll address this later.)


Fig. 2

For newcomers, the nuances of FM tuning are crucial to understanding Operator’s oscillators. Unlike traditional analog programming, the “coarse” knob tunes the oscillators to specific harmonics and not semitones or octaves, making it essential to understand the note relationships for each harmonic (see Figure 2). For example, the first harmonic is the fundamental, the second is an octave higher, the third is an octave plus a fifth, while the fourth is two octaves above the fundamental. There are numerous online resources for researching the exact relationships, but for getting started in a subtractive context, memorize the octave harmonics: 0.5, 1, 2, 4, 8, 16, 32 and 64.

In another twist, Operator’s fine-tuning knob always spans an octave, divided into 1,000 steps, with positive amounts only. So if you want to apply classic analog detuning on two oscillators you’ll need to set one oscillator an octave lower, then raise its fine tuning to between 980 and 999, which results in it being tuned slightly flat by a few cents. For the other oscillator, it’s much easier; simply raise its fine-tuning by a relative amount between 1 and 20. It sounds tricky, but it’s easy to get used to.

Fig. 3

For example, to create a four-oscillator detuned supersaw-style patch using the carrier algorithm, set two oscillators to a coarse tuning of 1 and the other two to a coarse tuning of 0.5 (sub-octave), then raise the fine tuning to +995 and +985 on the sub-octaves and +5 and +15 on the fundamentals (see Figure 3).


In addition to traditional subtractive waveforms, Operator’s oscillators also include an additive editor with up to 64 partials for each waveform. Any of the preset waveforms can be used as starting points for further editing, but here are two techniques to get you started on your own original waveforms from scratch.

Fig. 4

Formant Sculpting. Additive synthesis is useful for digital voice textures, and you can create vowel formants by attenuating or emphasizing specific clusters of harmonics (see Figure 4). Lower clusters correlate with “aahs” and “oohs,” while higher clusters are ideal for “eeee” sounds.

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