Allpassphase [ Extended · 2026 ]

In engineering, we often say: magnitude is what you hear first, but phase is what makes it real.

To understand an all-pass filter, you must first understand . Phase describes the timing of a waveform at a specific point in its cycle. When two identical sounds are "in phase," they sum together and get louder. When they are 180° "out of phase," they cancel each other out completely—a phenomenon known as destructive interference. allpassphase

This is the most famous use case. A pedal works by routing your guitar signal into two paths. One path is clean. The other goes through a series of allpass filters (often called "stages"). In engineering, we often say: magnitude is what

But there is a ghost in the machine. It’s a filter that doesn’t change the volume of anything. It leaves the frequency response perfectly flat. Yet, it is responsible for everything from the "sweetness" of a phaser to the tightness of a transient. When two identical sounds are "in phase," they