FAQ | What is linear phase and why should anyone care about it?

Learn about linear phase and understand why it is important for sound quality.

Updated at August 28th, 2023

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Linear phase means that all frequencies are delayed by the same amount when passing from the input to the output of a system. The image below depicts a square wave, a waveform that consists of a fundamental and odd harmonics (only two of which are shown). When the square wave passes through a linear phase system, the time relationship between fundamental and harmonics is preserved and the waveform that emerges maintains its square wave character.

In a system with non-linear phase, the time relationship between fundamental and harmonics is altered and something other than a square wave emerges at the output. Another term for altered waveform is distortion.

Phase non-linearity can be introduced by the electronics as well as by the transducers, waveguides, and other elements of a loudspeaker system. So linear-phase processing and amplification won’t deliver linear-phase acoustic output from the loudspeaker.