Comb Filter Calculator

Free tool to find where two mics or speakers cancel each other. No sign-up

Source to mic 1

Source to mic 2

Unit

Air temperature

Unit

Second signal has inverted polarity

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First dip in the frequency response

Model: two copies of the same signal summed, one delayed. In the "two mics" mode the level of the second signal follows the distance ratio in free field (6 dB per doubling). Real rooms, mic patterns and reflections change the result, so always listen.

What is comb filtering?

When the same sound reaches a microphone or a listener twice, once directly and once slightly later, the two copies add up and cancel at regular frequencies. The frequency response looks like the teeth of a comb. It happens with two mics on one source, with a mic and a reflecting surface, and with speakers that are not aligned.

Two mics, one source: enter how far the source is from each mic. The tool shows where the dips fall and how deep they are.
Delay or path: enter a delay in milliseconds, or a path difference, and how loud the second signal is.
The 3:1 rule: place the second mic at least three times farther from the source than the first. Its level drops about 9.5 dB and the combing stays mild.
Tick the polarity box to see what happens when one signal is inverted: dips and peaks swap places.

See other tools

Made by Luca Martone, sound designer and live sound engineer based in Turin.