Highpass Filter Node

Standard resonant highpass filter with 12dB/octave rolloff. Frequencies below the cutoff are attenuated; frequencies above it pass through.

That is, you can use this Node to only keep the higher frequencies of an audio source, and attenuate/mute the rest (e.g. to create an “elevator-like music” effect).

How to Use

The Highpass 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 Highpass 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. For control signals, the Highpass Filter Node essentially functions as a DC offset remover, i.e. it eases constant non-zero signals down to zero, depending on the cutoff frequency.

Frequency-Control Input

A control signal to control the Frequency setting. You can also connect an audio signal, but keep in mind that it can cause the Highpass 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.

Resonance-Control Input

A control signal to automate the Resonance setting, from 0.0001 to 1000.

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



The filter cutoff frequency, in Hz. Frequencies above this setting pass through, frequencies below are attenuated.


Sets how peaked the frequency is around the cutoff. The greater the value, the greater the peak.

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 Highpass Filter Nodes.


Audio Output

The filtered audio signal (or control signal).

Technical details

The Highpass 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 Highpass 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.

Node conversions

★ With AudioNodes HD

Node conversion is available from the node menu.

Convert to: Lowpass Filter Node

When converting, FrequencyFilter Order and Resonance values are transferred to the new Lowpass Filter Node