Multiple mic techniques

The most common application of multiple mic technique is recording the drum kit, and we can learn a lot from this. The technique combines mics at different distances from the kit, with overhead mics (often in a stereo configuration) providing a general picture, close-up ‘spot’ mics emphasising specific kit elements, and room mics (also often stereo) positioned at various distances to capture room ambience. A similar technique is used to record the orchestra, although the scale is larger and mic positioning is slightly different. In both cases, the thinking behind the technique is that it gives balancing flexibility. Sometimes, the mics are blended prior to recording, but usually, you’ll simply record all the mics, then balance them later on.

Further multi-miking examples include guitar amps, pianos and even vocals. With a guitar amp, you can use separate mics to simultaneously capture different parts of the speaker cone or cabinet. With piano, traditional stereo techniques can be augmented by single spot mics. In both cases, distant mics can be added to capture room ambience.

There are a couple of downsides to using multiple mics. First, they require more tracks, mics and inputs, which makes the setup more complex. Second, when you blend two or more mics capturing the same sound, you get phase cancellation and comb filtering, as the soundwaves arrive at the mics at slightly different times. The effect can be subtle or lead to deep notches or boosts at some frequencies, and with the latter, inverting the phase of one mic or track solves the problem. Other solutions include balancing different mics so that one is clearly dominant, or using plugins like Sound Radix Pi, built specifically to control phase relationships. Ultimately, you’re trying to make the mics sound the best they can, combined.