# ER-301/Limiter

## Contents

## 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.

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. |

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.

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. *C*^{2} 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.