Parametric EQ
Three-band parametric EQ with low and high cuts. Works on numbers, signals, and number arrays.
What it does
Parametric EQ shapes a signal with three sweepable bell bands plus a pair of brick-wall cuts. Each band has its own Frequency, Gain and Q (bandwidth): narrow a band to carve out a specific frequency, widen it for a broad tonal lift or dip. Low Cut and High Cut sit at either end of the chain as a high-pass and a low-pass filter, rolling off rumble or hiss without spending a band on it.
It works on audio Signals at full sample rate, and on plain Numbers and Number Arrays at the project's frame rate, so the same three-band shape filters an animation curve or a per-point value array.
When to use it
A three-band channel-strip EQ (bass, mid, treble), each band with its own frequency, boost or cut, and width
Taming a resonance or hyping a narrow frequency: high Q on a band, then Gain to taste
Clearing low rumble or high hiss: raise Low Cut or lower High Cut rather than spending a fourth band
The same EQ shaping applied to a non-audio value curve, fed in as a Number or Number Array
| Parameter | Type | Default |
|---|---|---|
input | OneOf([Number, NumberArray, Signal]) | — |
band1_freq | Number | 100 |
band1_gain | Number | 0 |
band1_q | Number | 1 |
band2_freq | Number | 1000 |
band2_gain | Number | 0 |
band2_q | Number | 1 |
band3_freq | Number | 8000 |
band3_gain | Number | 0 |
band3_q | Number | 1 |
low_cut | Number | 0 |
high_cut | Number | 20000 |
Gotchas
All three bands are true peaking (bell) filters, not shelves. High Gain with a low Q affects a broad range around the centre frequency; high Q narrows it to a thin notch or spike. Start with Q around 1.
Low Cut and High Cut are off by default: Low Cut starts at 0 Hz (disabled) and High Cut at 20000 Hz, the edge of human hearing (disabled). Move them inward to engage the cuts.
Gain is in dB and ranges from -24 to +24 per band. Pushing several bands hard in the same direction drives the output well above unity. Follow with a level or limiter stage when stacking boosts.
Worked example
Add a Parametric EQ and wire an audio Signal (or a Number/Number Array curve) into Input.
Set Band 1 Frequency low (around 100 Hz) and raise Band 1 Gain to add warmth, or lower it to thin things out.
Narrow Band 2's Q and sweep its Frequency to find and cut a harsh resonance in the mids.
Raise Low Cut to remove rumble below the material, and lower High Cut to tame hiss up top.
See also
Audio Mixer · Audio Analysis · Envelope Follower · Numbers, signals & audio