Theatre Design & Technology - Summer 1983 - 19

Helping The Operator,
A Workable Compromise
Farrel Becker of Audio Artistry,
Kensington, Maryland, uses an Industrial Research automatic mixer in a very
clever way. As shown in Figure I, Becker takes a preamplified output from
each channel of the main house mixing
console and feeds it into a separate
channel on the Industrial Research mixer. Becker then disables the feature
which turns the microphones on and off
by setting the "amount of off attenuation" to OdB. The Industrial Research
product appears to be the only available
mixer with the ability to completely defeat this feature. Defeating the on/off
feature means the automatic mixer is reduced to its second function, NOM reduction, only. Now, when the human
operator turns on two microphones instead of one (by bringing up their" faders" on the main mixing console) the
automatic mixer reduces its overall gain
by 3dB and helps the operator avoid
feedback. In this situation, the automatic mixer does exactly what a skilled
operator would do in precisely the correct way and, in doing so, frees the operator to concentrate on other functions.
This seems to be a very workable way to
use an automatic mixer as an operator
aid and Becker reports considerable success with the method.

operate lighting or whatever). For a
performance, the on/off switch would
be the only required "adjustment"
(providing there were no system
breakdowns).
While this system could not possibly
operate as well as if a skilled human

An Unattended Mixer Example
Under controlled circumstances, an
unattended automatic mixer in a dinner
theatre system (or other similar system)
could work quite well but I am unaware
of any existing dinner theatre using the
idea.
To make the system work unattended, you would have to set up the
microphone locations very carefully to
avoid picking up any signi ficant audience (or other ambient) noises (see Fig.
2). The actors would have to be very
aware of the microphones and would
have to direct their acting 10 lhe microphones perhaps even more than to the
audience (careful mike placement could
help avoid any connict here). A skilled
operator!technician would set up the
mixer (including any threshold and other adjustments as well as volume controls) during rehearsal and lock or tape
the controls so that nothing but the
on/off (Ae Power) switch could be
changed. At this point, the operator
could go home (or be assigned to

Acoustical consultants, Klepper Marshall
King Associates, recently experimented with
an Industrial Research Products DE-4013A
automatic microphone mixer for musical
theatre sound reinforcement. The unit was
employed at the Arie Crown Theatre,
Chicago, for the four-week engagement of
Gershwin's Porgy and Bess, produced jointly
by Radio City Music Hall and Sherwin M.
Goldman Productions. Larry King, principal in KMK, decided to use the DE-4013A
in this application for several reasons: I) the
full 100 ft. stage width of the Arie Crown
was to be used for the large performing
ensemble which required eight footlight
microphones (in this case, AKG C-451 's with
CK-I cardioid capsules); 2) the Arie Crown's
sound operator, Pat Reynolds, was to be
responsible for operating two "thunder and
wind" sound effects tape reproducers
simultaneously during the hurricane scene,
necessitating "extra hands" on the control
console, and extra human hands were not
available; 3) artisticallY, the producers wished to employ only a subtle boost for the
singers' voices, as appropriate to the operatic
nature of Gershwin's work.

Theatre Design & Technology/

operator were present, it would almost
certainly operate better than a similar
setup with a non-automatic mixer. The
non-automatic mixer could not turn microphones on in response to an actor's
voice and thus, all microphones would
have to be at full volume, all the time.

Mic or line input

Preamp output

IRPI Voice-Matic Mixer
000000
000000
000000

gggggg

Main output
Footlight or "area" microphone

Main mix bus input
or aux input

Mic input

~========?1
o
o
o

0
0

Farrel Becker uses all IRPI AU10/l/(J1ic
Mixer as all opermor aid 10 avoid feedback.
Main house mixing console

Loudspeaker
System(s)

Automatic mixer

Area or wireless mics

SITT /Sul11l11cr 1983

Power
Amplifier(s)

o
o
o
o

ITJJ

HYPo1he1ical ullal1ellded SYS1e/l/ for dillller 1hemre.

In addition to the automated group of
footlight microphones, three AKG
C-451/CK-9 "shotgun" condenser microphones at the footlights were mixed in the
conventional manner on the theatre's Yamaha PM-IOOO-32 console. The shotguns
were used only for distant (10-25 feet)
pickup, as required.
Interestingly, the "automatic" on-off
switching and related gain adustments could
be detected easily when listening over headphones to the output of the DE-4013A, but
these effects were completely masked when
its amplified output was mixed acouslically
with the theatre's direct and reverberant
sound fields.
KMK plans to include automated
microphone mixers (in addition to the IRP
device, models are available from other
manufacturers) in future theatrical sound
system designs as a "smart" electroacoustic
tool for theatre sound operators. The
DE-40l3A provided gratifying results at the
Arie Crown for Porgy and Bess. Music critic
John Von Rhein, of the Chicago Tribune,
cited in his review the "unobtrusive use of
amplification."
-Larry S. King, Vice Presidell1, KMK

Table of Contents for the Digital Edition of Theatre Design & Technology - Summer 1983