Filters
Filters shape the frequency content of signals by attenuating or boosting certain frequencies.
Filters shape the frequency content of signals by attenuating or boosting certain frequencies.
lp
Lowpass Filter - Passes frequencies below the cutoff, attenuates above.
| Param | Type | Default | Description |
|---|---|---|---|
| in | signal | - | Input signal |
| cut | signal | - | Cutoff frequency in Hz |
| q | number | 0.707 | Resonance (0.5-20) |
Aliases: lowpass, svflp
A state-variable lowpass filter. Higher Q values add resonance at the cutoff frequency.
// Basic lowpass at 800 Hz
osc("saw", 220) |> lp(%, 800) |> out(%, %)// Envelope-controlled filter sweep
osc("saw", 110) |> lp(%, 200 + ar(trigger(4)) * 2000) |> out(%, %)// Resonant filter
osc("saw", 110) |> lp(%, 500, 8) |> out(%, %)hp
Highpass Filter - Passes frequencies above the cutoff, attenuates below.
| Param | Type | Default | Description |
|---|---|---|---|
| in | signal | - | Input signal |
| cut | signal | - | Cutoff frequency in Hz |
| q | number | 0.707 | Resonance (0.5-20) |
Aliases: highpass, svfhp
Removes low frequencies. Useful for thinning out sounds or creating transitions.
// Remove sub frequencies
osc("saw", 110) |> hp(%, 200) |> out(%, %)// Hi-hat from noise
osc("noise") |> hp(%, 8000) * ar(trigger(8), 0.001, 0.05) |> out(%, %)bp
Bandpass Filter - Passes frequencies around the cutoff, attenuates others.
| Param | Type | Default | Description |
|---|---|---|---|
| in | signal | - | Input signal |
| cut | signal | - | Center frequency in Hz |
| q | number | 0.707 | Bandwidth (higher = narrower) |
Aliases: bandpass, svfbp
Isolates a band of frequencies. Higher Q values create a narrower, more resonant band.
// Telephone effect
osc("saw", 220) |> bp(%, 1000, 4) |> out(%, %)// Vocal formant
osc("saw", 110) |> bp(%, 500, 10) |> out(%, %)moog
Moog Ladder Filter - Classic 4-pole resonant lowpass filter.
| Param | Type | Default | Description |
|---|---|---|---|
| in | signal | - | Input signal |
| cut | signal | - | Cutoff frequency in Hz |
| res | number | 1.0 | Resonance (0-4, self-oscillates near 4) |
| max_res | number | 4.0 | Maximum resonance / self-oscillation threshold |
| input_scale | number | 0.5 | Input preamp drive (higher = more saturation) |
Aliases: moogladder
The legendary Moog ladder filter with its characteristic warm, creamy sound. At high resonance values, it can self-oscillate.
// Classic Moog bass
osc("saw", 55) |> moog(%, 400, 2) |> out(%, %)// Filter sweep with high resonance
osc("saw", 110) |> moog(%, 100 + osc("sin", 0.5) * 1000, 3.5) |> out(%, %)// Self-oscillating filter (use as oscillator)
osc("noise") * 0.01 |> moog(%, 440, 3.9) |> out(%, %)// Hot input with more saturation
osc("saw", 110) |> moog(%, 800, 2, 4.0, 0.8) |> out(%, %)Related: lp
sallenkey
Sallen-Key Filter - MS-20 style filter with aggressive resonance.
| Param | Type | Default | Description |
|---|---|---|---|
| in | signal | - | Input signal |
| cut | signal | - | Cutoff frequency in Hz |
| res | number | 1.0 | Resonance (0-4, very aggressive) |
| mode | number | 0.0 | Filter mode (0.0 = lowpass, 1.0 = highpass) |
| clip_thresh | number | 0.7 | Feedback clipping threshold |
Aliases: sk, ms20
Based on the Korg MS-20 filter topology with diode clipping in the feedback path. Creates the characteristic aggressive, screaming resonance.
// Classic MS-20 bass
osc("saw", 55) |> sallenkey(%, 600, 3) |> out(%, %)// Screaming resonance
osc("saw", 110) |> sallenkey(%, 400 + osc("sin", 0.2) * 800, 3.8) |> out(%, %)// Highpass mode
osc("saw", 110) |> sallenkey(%, 500, 2, 1.0) |> out(%, %)