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@maru shared this effect so you can build on it and use it in your DAW.

AvailableEffect

Auto Panner

Move a signal across the stereo field.

About

Auto Panner moves a sound back and forth between the left and right speakers. A sine wave sets the position, so a single mono source comes out as a stereo signal in motion.

The idea

Panning is the oldest way to make one sound occupy two speakers. A panner builds the two channels itself, so this works on a mono guitar, voice or synth without needing a stereo source.

Rate behaves like two effects. Below about 8 Hz your ear follows the movement and hears a position travelling. Above about 10 Hz the movement is too fast to track and turns into a rough texture with a stereo edge. The range goes up to 20 Hz so that end is reachable.

Controls

  • Rate is how fast the sound crosses the field, from 0.1 to 20 Hz.
  • Depth is how far toward each speaker the sweep travels. At full depth it reaches hard left and hard right.
  • Mix blends the moving copy with a still copy of the sound. Pulling it back leaves a stable image with movement around it instead of narrowing the sweep.
  • Position places that still copy anywhere from left to right. With Mix at zero, Auto Panner becomes a plain panner with no movement.

Getting started

Play a guitar, voice or synth through it and start with Slow Drift or Gentle Sway. Hard Ping-Pong throws the sound from side to side, Wide Pulse keeps a centre under a rhythmic sweep, and Flutter goes past the rate the ear can track.

At full depth the sound sits entirely on one side at the extremes, which half disappears if the mix is played back in mono. Moderate depths, or a Mix below 100%, hold up better on mono speakers.

How it works.

A sine LFO at Rate drives a stereo panner's position between full left and full right, with Depth scaling how far from centre it goes. That is the entire effect, it is amplitude modulation applied in opposite directions to two channels, which is also why a tremolo with its channels 180 degrees out of phase turns into one.

The browser preview runs it on a StereoPannerNode with the LFO summed into its pan parameter, all at audio rate. A panner constructs the two channels rather than requiring them, so this works on a mono source, which is the difference between this module and Stereo Widener, whose matrix has nothing to scale unless the input already carries a side signal.

Depth at 1 reaches hard left and hard right, and at the panner's equal-power law that means each channel is briefly silent while the other is full. Pulling Depth back keeps both speakers contributing throughout, which is usually what a mix wants; the extremes are more useful as an effect than as a placement.

What would you make with Auto Panner?

Describe what you want to make. Build it with the Studio agent.

Goes well with.

Building block

Periodic amplitude modulation with stereo phase control.

Building block

Adjust stereo width without changing the dry signal.

Prototype

Convolution reverb: eight synthesized spaces, twenty-five real cabinets.