# ER-301/Ladder HPF

## Contents

## Description

This is a digital simulation of the Moog ladder filter in a high-pass configuration with 4-poles (roll-off: 24dB/octave).

## Parameters

### V/oct

Control Type | Has Sub-chain? | Sub-chain Parameters | Fader Scale |

Pitch | yes | transpose (-3600¢ to 3600¢) | logarithmic ratio |

This parameter is used to transpose the base frequency up or down according to an incoming modulation value that is V/oct calibrated (typically one of the inputs from the ABCD matrix). In other words,

where is the value of this parameter (which is in cents). For example, if the base frequency (f0) is equal to 55Hz and this V/oct parameter is set to 2400¢, then the resulting frequency will be 220Hz (i.e. 2400¢ = 2 octaves which is 4x).

### f0

Control Type | Has Sub-chain? | Sub-chain Parameters | Fader Scale |

Gain/Bias | yes | gain (-10,000 to 10,000)
bias (5 octaves above and below 440Hz) |
frequency in Hertz |

This parameter sets the fundamental frequency that is subsequently transposed by the V/oct parameter. Modulating this parameter corresponds to (thru-zero) linear FM.

### Q

Control Type | Has Sub-chain? | Sub-chain Parameters | Fader Scale |

Gain/Bias | yes | gain (-10 to 10)
bias (0 to 1) |
linear |

This parameter controls the filter's resonance. Resonance is the result of a soft-limited feedback path. This parameter sets the gain on that feedback. The filter will typically self-resonate at values exceeding 0.5 to 0.6.