Additive synthesis builds sounds from the ground up, using sine waves.
A pure sine wave has no harmonics, and every sound we hear can be thought of as a stack of sine waves: one for the fundamental pitch, then one for each harmonic.
These harmonic waves are called partials.
Today’s computers can handle it, and Pigments gives you tools to work with the entire harmonic series.
This is in order to conserve CPU resources or work with a more manageable harmonic spectrum as you’re getting started.
The blue animated waveforms show amplitude of the partials of played notes in real time.
A number of controls shape the harmonic spectrum.
The Ratio control adjusts the pitch ratio between each partial and its nearest neighbour.
Parity is the proportion of odd and even harmonics. Odd and even refer to integer multiples of the fundamental pitch.
Pigments lets you set a continuous balance of the amplitude of odd and even harmonics: all odd, all even, or anywhere in between.
To relate this to the analog synth world, a 50/50 balance is basically a sawtooth wave. Triangle and square waves have all odd harmonics.
The triangle sounds mellower because the harmonics’ amplitude falls off more steeply as the pitch increases.
There actually isn’t a simple analog-style waveform corresponding to all even harmonics, but it’s easy to achieve in the Harmonic Engine, and has a pleasant sort of synth-harpsichord sound.
Partials decrease in volume as they get higher in pitch.
Tilt controls the steepness of that slope.
Tilt Offset changes the place in the spectrum where the slope begins.
That’s the Spectrum section. Spectrums are like complex multi-point EQ curves or comb filters.
These let you carve out different frequency areas of your additive waveform independently of the other controls.
You get 12 choices of spectrum shape and two spectrum slots.
Section changes the area of the overall harmonic series that the spectrum affects.
Morph lets you blend smoothly between the spectrums in the two slots.
Depth is simply the depth at which the spectrums affect the harmonic series.
The Imaging section lets you play with the position of partials in the stereo picture.
You can independently pan odd and even partials left and right (Split mode), randomly pan individual partials (Random mode), or pan clusters of partials (Periodic mode).
This reveals a nifty thing about the main Partials Viewer display: It shows how each partial is panned.
A vertical white line extending above the center horizontal line indicates leftward panning; below the center line indicates rightward panning.
Don’t forget — like most parameters in Pigments, these settings can be modulation destinations,
letting you do really interesting things with partials in stereo.
“Window” is actually one of three Partial Modulation Modes.
Window mode applies FM to a given window of partials within the overall harmonic series.
You can set the size, position, and gain of the window.
The source of the FM is the onboard Modulator oscillator (see below).
Cluster mode lets you bring partials within an adjustable window closer together, i.e. decrease the ratio for just certain partials.
Shepard mode shifts the frequency of each partial towards the next higher partial.
Again, the window within which this happens is adjustable. Modulating this effect can create the “Shepard’s tone” illusion, in which a sound always seems to be rising or falling in pitch even though its fundamental frequency does not change.
They are like the other engines. You can freely balance the engine’s output between Filters 1 and 2.