reson~

Resonant bandpass filter

Description

reson~ implements the following filter equation:

y[n] = gain * (x[n] - r * x[n-2]) + c1 * y[n-1] + c2 * y[n-2], where r, c1, and c2 are parameters calculated from the input center-frequency and Q. Q is the filter-bandwidth divided by center-frequency. Inputs can be floats or signals.

Arguments

Name Type Opt Description
initial-gain center-frequency and Q int or float opt Numbers set the initial gain, center frequency, and Q. The default values are 0 for gain, 0 for center frequency, and 0.01 for Q.

Messages

int initial-gain/center-frequency/Q [int]
An int or float can be sent in the three right inlets to change the filter-gain, center-frequency, and Q. If a signal is connected to one of the inlets, a number received in that inlet is ignored.
float initial-gain/center-frequency/Q [float]
An int or float can be sent in the three right inlets to change the filter-gain, center-frequency, and Q. If a signal is connected to one of the inlets, a number received in that inlet is ignored.
list initial-gain center-frequency and Q [list]
The first number sets the filter-gain. The second number sets the filter center-frequency. The third number sets the filter-Q. If any of the inlets corresponding to these parameters have signals connected, the corresponding value in the list is ignored.
clear Clears the filter's memory. Since reson~ is a recursive filter, this message may be necessary to recover from blowups.
signal In left inlet: Any signal to be filtered.

In left-middle inlet: Sets the bandpass filter gain. This value should generally be less than 1.

In right-middle inlet: Sets the bandpass filter center frequency in hertz.

In right inlet: Sets the bandpass filter "Q"-roughly, the sharpness of the filter - where Q is defined by the center-frequency divided by the filter-bandwidth. Useful Q values are typically between 0.01 and 500.

Information for box attributes common to all objects

Output

signal: The filtered input signal. The equation of the filter is

yn = gain * (xn - r * xn-2) + c1 * yn-1 + c2 * yn-2

where r, c1, and c2 are parameters calculated from the center frequency and Q.

Examples

Control gain center frequency and Q of a bandpass filter to alter a rich signal

See Also

Name Description
biquad~ Two-pole, two-zero filter
comb~ Comb filter
onepole~ Single-pole lowpass filter
lores~ Resonant lowpass filter
Resonant bandpass filter