© 2000 James Walker

Excerpted from James' instructional CD-ROM, Signal Processing for Vibraphonists

Because of the size of the vibraphone, two microphones are usually used to amplify or record the instrument; a single microphone usually will not provide even coverage of the entire range of the vibes. Here are some commonly-used stereo microphone setups.

"X-Y CONFIGURATION"

(Note: also can be accomplished with a single, stereo microphone)

ADVANTAGES no phase cancellation stereo imaging mallet contact sound is picked up by microphones

DRAWBACKS stereo image not as strong as with spaced stereo pair risk of leakage from other instruments into vibe mic's mic's can interfere with mallets

"SPACED STEREO PAIR (FROM ABOVE)"

ADVANTAGES optimal stereo imaging more even coverage of instrument compared to X-Y technique mallet contact sound is picked up by microphones

DRAWBACKS risk of phase cancellation risk of leakage from other instruments into vibe mic's mic's can interfere with mallets

"STEREO PAIR (FROM BELOW)"

ADVANTAGES no interference with mallets mic's isolated from other instruments/sounds

DRAWBACKS any rattles or frame noise are amplified mic's read less of the mallet "contact sound"

THE "3-TO-1 RULE"

Phase Cancellation is a result of a sound reaching different microphones at slightly different times (or, "out of phase") - in other words, the same sound reaches two different microphones at a delay. If the difference is very slight, then the different sound waves can cancel each other out, making the amplified or recorded sound very "thin." This is especially the case when the two microphones' signals are combined into a single monophonic signal, such as plugging two mic's into an amplifier with only a single speaker. The "3-to-1 Rule" ensures that such phase cancellation will not occur by guaranteeing that the effects of any phasing which does take place, will be minimized by the spacing of the microphones. By keeping the microphones three times as far from each other as they are from the sound source, the delay as the signal reaches the different microphones will be too great to cause a degredation of the sound. (This page and all the materials within copyright ©2000 James Walker, All Rights Reserved.  No portion of this page may be duplicated or distributed without the author's written consent.)

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