Additive synthesis: in Operator

Subtractive synthesis starts with a harmonically rich waveform and takes things away. Additive goes the other way: start with nothing and stack up sine waves until you have a sound. Operator lets you do it by hand, with a pencil.

Draw a waveform

1. Load Operator and switch the display from Envelope to Oscillator.
2. In the Wave chooser, pick User. The display is now empty and yours.
3. Move the mouse over the display — the cursor becomes a pencil. Each vertical bar is one harmonic, and its height is that harmonic's level.
4. Draw the first bar tall. That is your fundamental: a sine wave, and nothing else.
5. Add the third harmonic, then the fifth, then the seventh, each a little quieter than the last.

You have just built a square wave from scratch — odd harmonics only, rolling off as they climb. Add the even ones back in and it becomes a sawtooth. This is the fastest way to actually understand what the waveforms in every other synth are made of.

The controls that matter

• Hold Shift while dragging to change one harmonic at a time instead of painting across several.
• The switches to the right of the display move you between the first 16, 32 or 64 harmonics.
• Repeat generates the harmonics above your drawing by repeating what you drew, fading out as it goes. Low values sound brighter; high values roll off the top and leave the fundamental dominant. Turn Repeat off and everything above your last drawn harmonic is simply gone.
• Right-click for even or odd harmonics only — the quickest way to hear the difference between a square and a saw.
• Also in the right-click menu: Normalize. On, the oscillator holds its output level as you add harmonics. Off, every harmonic you add makes it louder. Leave it on unless you enjoy surprises.

Keep what you make

Right-click and export the waveform as an .ams file into Samples/Waveforms in your User Library. Drag it back onto any Operator oscillator to reload it — and it will load into Simpler and Sampler too, which is a quiet little back door into using your own single-cycle waveforms across three different instruments.

You can also copy and paste a waveform straight from one oscillator to another from the same menu.

Where it gets interesting

A drawn waveform is static — it is still one shape. The additive part starts when each harmonic gets its own envelope, which is what Operator's four oscillators are for: tune them to 1, 2, 3 and 4, give each its own level envelope, and the harmonic balance now changes over the life of the note.

That is how real instruments behave. A piano's high harmonics die away long before its fundamental does. Build that and a synth stops sounding like a synth.

Do this now

1. Draw a square wave by hand in Operator's User slot - odd harmonics only, rolling off.
2. Add the even harmonics and hear it become a saw.
3. Export it as .ams and load it into Simpler.

Building the waveforms by hand is the fastest way to understand what every other synth is starting from.