Bandpass Filter Node

The Bandpass Filter Node attenuates frequencies outside the given frequency range, and only allows frequencies inside the range to pass through.

Simply put, you can use this Node to only keep a given range of frequencies in an audio source (e.g. frequencies around 1 kHz), and attenuate/mute the rest.

How to Use

The Bandpass Filter Node needs a source audio signal connected to its audio input, to which it can apply the effect, and then output the result. The input audio signal can come from anywhere, as long as it's audible: an Audio File Node, Oscillator Node, Noise Generator Node all work. Click their output, then click the audio input of the Bandpass Filter Node to establish a connection.

Connect to an Audio Destination Node to listen to the output, and play your project if your audio source needs it.


Audio Input

An audio signal to filter. You can also connect a control signal, but results will vary based on whether the control signal changes in a way that conveys meaningful frequency information, or not.

Frequency-Control Input

A control signal to control the Frequency setting, in Hz. You can also connect an audio signal, but keep in mind that it can cause the Bandpass Filter Node to become unstable and reset. See the technical details section below.

You can enable this input from node properties, or by connecting to it.

Sharpness-Control Input

A control signal to control the Sharpness setting, from 0.001 to 1000.

You can enable this input from node properties, or by connecting to it.



The bandpass filter’s center frequency, in Hz.


How sharp/narrow the frequency bandwidth is around the center frequency. Greater values result in a smaller frequency band, and a sharper effect. For example, very high values can create a soft whistling sound out of a white-noise source.

Filter Order

The order of the differential equation describing the filter. In simpler terms, when you increase the filter order, it’s essentially the same as chaining multiple Bandpass Filter Nodes.


Audio Output

The filtered audio signal (or whatever is left of the control signal if that’s what you connected).

Technical details

The Bandpass Filter Node is a digital biquad filter, and as such, it's possible for it to become unstable, e.g. in response to rapid frequency modulation. When this happens, the Bandpass Filter Node will attempt to reset itself every few seconds, to avoid remaining unstable forever. This auto-reset is done in real-time mode (i.e. when you play your project), but not during exporting. That is, if the filter becomes unstable while exporting, it may remain unstable until the end of the exported audio.

Note: the behavior of this auto-reset is mostly non-deterministic, and depends on several undocumented factors. Don't rely on it to produce "glitchy" audio. Instead, use a Gain Node with an LFO-controlled gain, or a similar amplitude modulation technique.