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Instruo Tanh[3]

Tanh[3] is a three channel, all analogue, wave shaper. It takes an input signal and outputs the hyperbolic tangent function [tanh(x)] for that signal.

In more useful terms, it adds curves to a signal!

Traditionally the circuit is used to shape a triangle wave to a sine but when used with more complex signals it behaves as a single knob limiter.



Depth: 27mm


+12V: 15mA
–12V: 10mA


The tanh[3] has three independent channels for wave shaping.


For many Max/MSP and/or PD users, the [tanh~] object may be familiar. It is likely a much used secret weapon in many contexts!

Describing what the tanh[3] does to a signal, both mathematically and sonically can be a headache, and not particularly useful. So I will describe some particularly fun use cases to give a bit of context.

Feedback control: 

Feedback is fun. But feedback can get unpredictable.

The user can insert tanh[3] in the feedback path and use it to reign in runaway feedback. Whether it’s feedback in a delay loop, a reverb, filter or straight up microphonic

In this context, it functions as a limiter on feedback amplitude.

Instead of fading away to silence, when longer sustain is desired, or running away uncontrollably, a signal can be controlled much more easily with a tanh[3]. There will be a much wider range at which a feedback oscillation will stabilise musically.

Wave shaping:

Running a triangle wave through a tanh[3] will allow for some interesting wave shape control

Fully CCW and the resulting signal will be a slightly attenuated pass through of the original triangle wave. As the level is increased, the corners will soften and the waveform will shape into a sine wave.

When a level has increased the sine will soft clip and eventually settle into a unique peaked waveform.


tanh[3] reacts very well when the user runs a complex audio signal through one of the channels. Drum voices especially!

The effect is sonically similar to compression but achieved through wave shaping as opposed to gain reduction. Limiting is a more appropriate description but it definitely has its own unique characteristic.

Increasing the level will introduce soft clipping distortion/overdrive.