What is proximity effect in microphones?

Proximity effect manifests itself as an increase in low frequency response when a sound source moves close-up to a microphone. How pronounced this boost is varies between mics depending on their design and polar pattern. It is noticeable on most cardioid microphones when, for example, a singer gets within a few inches of the capsule (Omni-directional mics have no proximity effect due to their transducer type).

Like many facets of a microphone’s performance, proximity effect may or may not be a good thing, depending on the desired result. The more low-frequency content in the sound source, the more pronounced the effect so, for example, when recording a guitar cab close-mic’ing can give a fuller, ‘beefier’ sound, or could equally cause an overly boomy sound. Similarly with vocals, proximity effect can add to the grit and gravel of a voice and add depth and warmth, or could be overbearing and boxy-sounding.

It’s best, as ever, to use your ears to judge – but watch that input meter, as the levels will go up as the mic goes closer to the source.