ER-301/Limiter

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Applications

  • Gain-staging
  • Memory-less saturation
  • Soft-limiting
  • Adding odd harmonics to sinusoidal waveforms (i.e. squaring off or flattening peaks)
  • Sound design
  • Shaping modulation signals (envelopes and LFOs)
  • Taming feedback loops

Description

This unit implements 3 simple limiting algorithms: hard, cubic and inverse square root. The hard algorithm adds the most (odd) harmonics while the inverse square root adds the least. Furthermore, there are separate pre-gain and post-gain stages so that you can dial in the exact amount of non-linearity that you desire in the final output.

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Inserting a Fixed HPF (high pass filter) unit right before a Limiter unit is a great way to maximize dynamic range. The HPF will remove any (inaudible) DC offset which if left alone would reduce the headroom available for higher frequencies.


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The opposite of the above tip is to place an Offset unit before a Limiter to cause pre-mature clipping (under CV control) on purpose as a kind of sound design technique.


Hard Limiting

Any signal above 1 is clipped to 1 and any signal below -1 is clipped to -1.

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Whether you use a Limiter or not, signals are always passed through a hard limiter right before being sent out to the DAC (i.e. OUT1-4).


Cubic Limiting

The input range between -1.5 and 1.5 is mapped to a cubic spline and clipped outside that range in such a way that the first and second derivatives are continuous everywhere (i.e. C2 smoothness).

Inverse Square Root Limiting

The output asymptotically approaches 1 from below and -1 from above. This limiting function is the softest of the three.

Parameters

pre-gain

Control Type Has Sub-chain? Fader Range Fader Scale
Simple Fader no -36dB to +36dB logarithmic gain


This gain multiplies the signal before the non-linearity affects it.

type

Control Type Has Input? Choices
Option no hard, cubic, inv. sqrt


Here you choose from one of the 3 available limiting functions: hard, cubic and inverse square root.

post-gain

Control Type Has Sub-chain? Fader Range Fader Scale
Simple Fader no -36dB to +36dB logarithmic gain


This gain multiplies the signal after the non-linearity affects it.