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Adds distortion with direct control over distortion harmonics (Chebychev waveshaping).

Shaper creates harmonic distortion using a technique called waveshaping. It lets you graphically edit the relative strength of the first 27 harmonics in the distortion. The resulting signal varies, depending on the harmonic content and amplitude of the input signal.

See the Adjusting Contraption Properties section for information about using sliders, knobs, presets etc.

Related Contraptions

DigiGrunge, Compressor, Limiter


Shaper parameter editor window

Input Gain


Controls the level of the input signal. Because of an internal scaling algorithm, Input Gain affects only the amount of shaping distortion applied, and not the output level of Shaper.

Output Gain


Controls the output level independent of the Input Gain.

Harmonic weightings

(Weight_1 - Weight_27)

Controls the relative strengths of the harmonics. Move the mouse over the graph to highlight individual harmonics, numbered from 0 to 27.

Harmonic 0 is equivalent to the input signal only, and you will hear no variation to the harmonic weightings if this is the only harmonic selected. To select other harmonics, click on any harmonic from 1 to 27 and drag up and down with the mouse to change the strength of the harmonic. Odd harmonics are displayed red, and even harmonics are blue.

Holding down the shift key while positioning the mouse over the Harmonic weightings graph will highlight all of the even-numbered harmonics. When shift is held down, you can drag the mouse horizontally over the harmonic graph to “paint” the even harmonics. If you hold down the control key instead, all of the odd-numbered harmonics will be highlighted, and can then be “painted”. When both the shift and control keys are depressed, all harmonics can be “painted”.

Shaping function

Displays a graph of the distorting function. Input is graphed on the horizontal axis, and output on the vertical axis.


Shaper is very sensitive to input level. Varying amounts of distortion will be produced depending on the level of the input. If you vary the Input Gain, you can create interesting shifts in the harmonic balance. Overdriving Shaper may produce harsh clipping distortion.

Relevant Example Files

The following files provide some examples of how Shaper can be used:

ShapeSynth.amh, Chemutengure-MbiraMelody.amh & TranceRiffer.amh

To open the Example Files directory, go to the File menu, select Open, and double-click on the Examples folder. Read descriptions of the example files here.

Suggested Uses and Practical Applications

Ross Bencina says: “Use Shaper as a flexible distortion processor. You may need to distort only the first few harmonics to create complex distortion effects. The more complex the input sound is, the less distortion is required to create a noticeable effect.” Also: “Use Shaper for non-linear waveshaping synthesis. Use a sine wave or other simple waveform (such as those generated by TestGen or 10Harmonics) as your input, and modulate the Input Gain to synthesize various harmonic spectra. With a 0dB sine wave as input and maximum Input Gain, the relative strength of the harmonics in the output will match those specified in the Harmonic weightings graph. Changing the Input Gain will produce different harmonic weightings.”

Technical Discussion

Shaper uses the Chebychev polynomial technique to compute the waveshaping function. Whenever a harmonic weighting is changed, Shaper recomputes the waveshaping function. As this is a time consuming operation you can expect the CPU usage to increase if you control the weightings using automation, MIDI or the Metasurface.

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