Basically, if you have three floor mics, the signal of each goes to a separate amplifier channel and loudspeaker. The three loudspeakers are mounted close together. The number of open microphones per PA “system” is one, providing maximum GBF and clarity.
And what’s great is that all three mics can be turned up the entire time, which is much easier than trying to follow the action and riding mixer faders to minimize the NOM.
The three loudspeakers are placed close together so the audience does not hear the sonic image shift as an actor moves across the stage. One might argue in favor of separating the loudspeakers, and having the stereo image follow the actor. However, that effect is usually valid only for people sitting near the center of the audience.
Stacking Loudspeakers: Rather than deploying loudspeakers to each side of the stage, instead mount a single loudspeaker at one corner of the audience, shooting across to the opposite corner. Or, stack two loudspeakers (horn to horn), which narrows their vertical dispersion. (And be sure to clamp them together solidly so they don’t “vibrate” apart.)
This approach, suggested by consultant Ray Rayburn (which I also pointed out in the June 2010 issue of LSI) eliminates the comb filtering that occurs with two loudspeakers at different distances, and also produces a clearer sound with less reverb because of reduced ceiling reflections.
Hiding Loudspeakers: In some venues, there’s a desire for the loudspeakers to be hidden from view. visible.
Common tricks to conceal them, without blocking their sound, include painting loudspeakers to match surrounding walls/scenery; concealing them behind plants; covering them with thin fabric of the same color as walls/scenery; and covering them with silk or nylon so they look like artwork.
Bipole Assembly: Mount two loudspeakers back-to-back and wired with opposite polarity. This creates a quasi-bidirectional or figure-8 dispersion pattern, dramatically reducing sound radiation at the sides. This allows placement of loudspeakers to the side of a person speaking by reducing the chances of feedback.
Unlimited Opportunities: There are also wireless options, body-worn options, loudspeakers in enclosures that look like rocks, and so on.
Listing all of the alternatives and applications of the humble yet mighty 2-way loudspeaker could fill the rest of this issue. There’s virtually something for everything, with possibilities limited only by the imagination of the user.
AES and SynAudCon member Bruce Bartlett is a microphone engineer, sound system designer, recording engineer, and audio journalist.