Handbook for Sound Engineers

1282 Chapter 34

group with a single fader. Assign the groups to the
master left and right outputs to feed the auditorium
loudspeaker systems.
For individual channel special effects, use that
channel’s insert feature. For special effects on a group
of sources, use an auxiliary group. In the religious
facility example, certain spoken voices may benefit
from artificial reverberation during a dramatic presenta-
tion. Assign these voices to an auxiliary group and feed
the aux group output to the reverberation device. Return
the output of the reverberation device to an unused
input channel or other available input.

For stage monitor mixing, assign selected inputs to
an auxiliary group to feed a stage monitor loudspeaker.
By using two or more auxiliary groups, the operator can
provide customized mixes for different needs on the
stage. In the religious facility example, the choir needs
to hear the spoken voices and musical instruments, but
may not need to hear itself in the monitor mix. In
contrast, the pastor or a lay reader needs to hear the
choir and musical instruments but does not need to hear
the spoken voices.

If the mixing console has a matrix output, use this
section to feed the various loudspeaker systems. Assign
groups (and aux groups) to the matrix outputs to
achieve an optimum mix for each loudspeaker system.
In the religious facility example, use matrix outputs 1,
2, and 3 to feed the auditorium left, center, and right
clusters. Use matrix output 4 to feed the under-balcony
loudspeakers. Use matrix output 5 to feed any external
overflow rooms, mothers’ rooms, and offices. Use

matrix outputs 6 and 7 to feed a stereo recording or live

broadcast feed.

By using the matrix outputs in this manner, each loud-

speaker system or recording or broadcast feed can have a

custom mix. In the religious facility example, the audito-

rium loudspeaker clusters need all of the groups except

the electronic organ, which has its own loudspeaker

system in the auditorium. The recording or broadcast

feeds, and the overflow room feeds, however, need the

organ and perhaps an audience response microphone

feed. Custom mixes like this can be set up in the matrix

and need very little adjustment during a performance.

34.4.3 Automatic Microphone Mixing

Many of the tasks a human operator performs on a sim-

ple mixer are predictable. For example, the human oper-

ator turns up the volume controls for microphones that

are in use and turns down the volume controls for

microphones that are not in use. In addition, an experi-

enced human operator will turn down the master vol-

ume control about 3 dB each time the number of in-use

microphones doubles to help avoid feedback from the

NOM problem discussed in Section 34.2.2.5. An auto-

matic mixer performs these two functions without the

aid of an operator, Fig. 34-40.

The first commercially successful automatic mixer

was invented and patented by Dan Dugan, a consultant

in San Francisco, and marketed by Altec Lansing Corp.

The Dugan automatic mixer exclusively used analog

Figure 34-38. A digital mixing console. Courtesy Yamaha.