Close-miked vocal tracks can often produce strange splatters of high-frequency noise when fed through a digital reverb algorithm. If your goal is a smooth and natural reverberation, then this effect can be distracting. This effect doesn’t really happen in natural reverberant environments like the concert halls and cathedrals that these algorithms are modelled after, unless you are feeding a close-miked vocal through a loud PA system in such an acoustical space. The problem lies in the “s” and “t” sibilant consonants that are aggravated into a type of high-frequency overload distortion by the microphone itself. The simple solution here is to insert a de-esser into the aux send signal path. This will suppress the sibilants that would over-excite the reverb.
In a recording situation, another solution is to place an additional microphone to the side or behind the singer, with the signal acting as a reverb feed only. The sound from these microphone positions will not have any sibilants.
Close-miked acoustic guitar signals can also play havoc with digital reverbs: they exaggerate the squeaks produced by the fret board hand movement. Here again, you could use a spare microphone (or two) placed behind the player as a reverb send signal. The sound, as picked up from behind, will be less detailed but fuller and rounder. This will provide a more indirect “average” feed to the reverb that will be void of those extraneous hand noises.
Another solution I have often used is to place a (cheap) transducer-pickup on the guitar. In this application the pickup signal again lacks the highs and squeaks present in a front placed main microphone. This smoother, more average sound is better suited as a reverb feed.
John Klepko is a sound engineer/producer and musician based in Montreal, PQ. He is currently in the final throes of his Ph.D. music degree (from McGill University) in the area of surround-sound. John also teaches courses in sound recording at McGill University and Concordia University.