Band Pass Filter

amp: 1 mix: 1 pre_amp: 1 centre: 100
res: 0.6

with_fx :bpf do
  play 50
end

Combines low pass and high pass filters to only allow a ‘band’ of frequencies through. If the band is very narrow (a low res value like 0.0001) then the BPF will reduce the original sound, almost down to a single frequency (controlled by the centre opt).

With higher values for res we can simulate other filters e.g. telephone lines, by cutting off low and high frequencies.

Use FX :band_eq with a negative db for the opposite effect - to attenuate a given band of frequencies.

Introduced in v2.3

Options

amp:

The amplitude of the sound. Typically a value between 0 and 1. Higher amplitudes may be used, but won’t make the sound louder, they will just reduce the quality of all the sounds currently being played (due to compression.)

Default: 1
Must be zero or greater
May be changed whilst playing
Has slide options to shape changes

mix:

The amount (percentage) of FX present in the resulting sound represented as a value between 0 and 1. For example, a mix of 0 means that only the original sound is heard, a mix of 1 means that only the FX is heard (typically the default) and a mix of 0.5 means that half the original and half of the FX is heard.

Default: 1
Must be a value between 0 and 1 inclusively
May be changed whilst playing
Has slide options to shape changes

pre_amp:

Amplification applied to the input signal immediately before it is passed to the FX.

Default: 1
Must be zero or greater
May be changed whilst playing
Has slide options to shape changes

centre:

Centre frequency for the filter as a MIDI note.

Default: 100
Must be a value greater than or equal to 0
May be changed whilst playing
Has slide options to shape changes

res:

Filter resonance as a value between 0 and 1. Large amounts of resonance (a res: near 1) can create a whistling sound around the cutoff frequency. Smaller values produce less resonance.

Default: 0.6
Must be zero or greater,must be a value less than 1
May be changed whilst playing
Has slide options to shape changes

Slide Options

Any parameter that is slidable has three additional options named _slide, _slide_curve, and _slide_shape. For example, 'amp' is slidable, so you can also set amp_slide, amp_slide_curve, and amp_slide_shape with the following effects:

_slide:

Amount of time (in beats) for the parameter value to change. A long parameter_slide value means that the parameter takes a long time to slide from the previous value to the new value. A parameter_slide of 0 means that the parameter instantly changes to the new value.

Default: 0

_slide_shape:

Shape of curve. 0: step, 1: linear, 3: sine, 4: welch, 5: custom (use *_slide_curve: opt e.g. amp_slide_curve:), 6: squared, 7: cubed.

Default: 5

_slide_curve:

Shape of the slide curve (only honoured if slide shape is 5). 0 means linear and positive and negative numbers curve the segment up and down respectively.

Default: 0