Theatre Design & Technology - Fall 1979 - 28

forms are merely compressed into the tops and bottoms of the
signal excursions.
A further analysis of the harmonic elements in the distortion
products shows an almost exclusive third-harmonic product
until the input level is increased severely, over 15-20dB. Only
at that point do any higher order harmonic elements begin to
contribute significantly. Hamm, in his analysis of harmonic
distortion in overloaded conditions, describes the third harmonic as a musical element producing a "stopped," "covered," or "blanketed" sound'3 He describes the third harmonic as one of the more pleasant distortion elements,
relatively musical in comparison with the higher order elements more commonly found in overload distortion.
The result of this characteristic is that the input stages are
less prone to unpleasant sounding distortion when overdriven,
and their tendency to limit peaks may assist the operator in
preventing overloading in subsequent stages with very dynamic material.

two duplicate A group controls and comprise a slider for fade
time, the toggle switch directly below the slider, and on either
side of the switch are two lights providing visual indication of
the relative levels of the duplicate voltage-controlled amplifiers. The two scales on the time slider give approximate times
for the level to drop to -40 dB, indicated by an arrow pointing
down, and for the relative level to rise to -40 dB in the alternate channels, indicated by the arrow pointing up.
The lower left portion of the panel contains facilities for input group B, with facilities identical to group A, and controls
for inputs 7 and 8. The input attenuation switches are located
directly above the sliders for 7 and 8, with the tone controls
below. These tone controls are Baxendall type with maximum
boost and cut of about 15 dB, and the calibration markings
are primarily for reference. 14 All input facilities occupy the lefthand third of the panel, with the output preset matrix sliders
covering the rest.

Future

Console

Because this unit is a very basic one, flexibility and versatility could be improved. This has already been realized in a unit
half again as large as this. This larger console is less applicable to the needs of most theatres, however, as it incorporates three quadraphonic input groups, twelve output presets
each with equalization, and twenty-four output channels.
Improvement could be made within the format of the model
described through the addition of access points for insertion
of external delay units or equalization into internal signal
paths; and models will be available with these facilities. Additional signal processing may be added to input and output
lines to add to flexibility without modification.

The upper left section of the panel (Fig. 5) contains the
controls for input groups A and C. Sliding level controls for
each input channel, duplicated for the A pair, are calibrated
in points from 0 to 10 with each point representing approximately 6 dB. Below each slider is a row of six push buttons
performing the first matrix function. The buttons are provided
with an interlock without lockout. This enables the operator to
select a new output preset without having to cancel the previous one, yet two buttons in each row may be depressed simultaneously if desired.
Control facilities for the crossfading circuit are between the
Fig. 5 Control panel of console.

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Charles Richmond has worked as a free-lance sound designer and audio consultant with such theatres as the American Conservatory Theatre,
Stratford Festival of Canada, and the San Diego Shakespeare Festival. He is currently president of Richmond Sound Design Ltd.
Table of Contents for the Digital Edition of Theatre Design & Technology - Fall 1979
