Spectrum Filter

Overview

The Spectrum Filter is the spectral-filtering and spectral-additive synthesis unit of Cycle.

It also gives control of the phase spectral domain which can be used to great effect in natural sounds.

Like the Time Surface, this component has two editors that show different perspectives of the spectral information.

The spectrogram view is a topographical perspective showing the spectrum's evolution over time (or another morphing range).

The 2D spectrum view showing the sound's harmonic spectrum at a particular moment in time set by the playback bar.

There are also two halves of the spectral domain - harmonic magnitudes and harmonic phases. Each of these has an independent set of layers.

Magnitude Spectrum Editor

This is the 2D view of the spectrum, plotting the harmonic magnitudes in ascending frequency.

In the foreground is the spectral curve wireframe.

Behind it is the spectrum of harmonic magnitudes of the waveshape.

Magnitude Spectrogram Editor

This area shows the spectrum of the sound as it evolves over a morphing range.

The visualization is like a topographic map of the changing spectrum.

Different magnitude levels are distinguished between visually by the colouring scheme: black = low, blue = medium low, magenta = medium, orange = medium high, white = high.

The lines in this editor are the vertex paths distorted by a scratch envelope.

Phase Spectrum Editor

This is the 2D view of the phase spectrum, plotting the harmonic phases in ascending frequency.

In the foreground is the spectral curve that adds to the analysed phase spectrum.

Phase Spectrogram Editor

In this view you can see the unwrapped phases of the cycles of our sound across a morphing range.

Harmonic phases are values between 0 and 2π. Phase unwrapping means that from one cycle to the next, if the phase jumps from the highest value to a low value we can be confident it's drifted higher and wrapped rather than jumping down. If we correct for this, we get a smooth pattern out of the chaos that looks like the above visual.

With this visualization, we can see if certain harmonics drift one way or another. This is particularly obvious in plucked instrument samples samples when they are analysed.

Layer Controls

Select between viewing the magnitude and phase domain.
Enable / disable current layer of the selected domain (magn. or phase).
In the magnitude domain, this set the layer mode to either spectral-additive or spectral-filtering.

Spectral-additive layers will add the curve to the magnitude spectrum (even if the spectrum is zero).

Spectral-filtering layers will multiply the curve with the magnitude spectrum and so behave like a filter.
Layer's Scratch Selector. This connects a scratch envelope to this layer and the envelope then distorts the timeline of the curve wireframe.
Add or remove a spectrum layer.
Move the current layer up or down in the stack. This is only applicable for magnitude-domain layers, where order matters because of the two modes.
Layer selector - left drag or use scroll wheel to change the current layer. The total number of layers is shown in subscript to the right the current layer number.
Layer pan. Use this to make a stereo oscillator with two layers panned to opposite sides.
Layer range. Changes how much the layer's curve affects the spectrum.
Mesh Selector for spectrum mesh files.