ONE OF the most important
technical aspects of live studio operations is the technique of
audio mixing. While the technique
naturally varies from one engineer to another, the man who combines musical knowledge with a
good memory and keeps calm under pressure, is the type who eventually gets his name in the credit
lines for number of important
network shows.
Our first consideration is the
method used in setting up the
mixer board. There seems to be
an inherent urge on the part of
most audio engineers to set up
their mixer readings from left to
tight—that is, with the most important mics tied to the left-hand
mixing pots. This tendency has
probably been carried over from
the early days, when it was prudent to connect the announce mie
to the number 1 pot, so that it
could be grabbed in an emergency
without looking.
In most instances this mic doubled as the vocal mie for an orchestra setup, and the rest of the
board was arranged about like Fig. 1A.
This simple arrangement
could handle many shows involving house band and vocalist, but
when expanded to meet the modern demands of a complex show,
the board tends to be off balance
to the left. Such an arrangement
is shown in Fig. 1B. Because only
two pots of the large-knob rotary
type can be simultaneously controlled with one hand, the most
important pots, requiring the
most gain riding, are not conveniently placed. This, of course,
makes the mixing job more difficult.
Fig. 1C illustrates a more sensible method of setting up the
mixer suitable for a large musical
TV show, with the addition of
two submixers to accommodate
the relatively large number of microphones more easily on conventional console. The submixers
(which may be outboard portable
units) feed into two pots on the
main mixer panel for a more compact two-hand layout within a rea-
.sonable span. Note that the left
hand may normally control the
string mie and Boom 1, while the right hand controls Boom 2 and
the chorus mic. The most important mics are comfortably çentered and under complete control,
and a hand occasionally can be released to touch up the woodwind, muted brass, audience reaction
mics, etc.
A room tone or echo mic is
shown submixed with the string
mic. This idea works well in a
large, but typically deadened studio. Even in a theater studio it
will help to augment the sound of
a small string section. As the
string mic is opened, room tone
tends to counteract the "rosiny"
sound of a close-miked string section.
The Importance of
Microphone Choice
The second important consideration for improvement of TV au dio is the choice of microphone
used on the stage booms. Even
casual examination of the comparative curves of the older ribbon cardioids and dynamic/ribbon
combination cardioids shows considerable leakage at both ends of
the spectrum (Fig. 2). The frontto-back ratio is quite poor except
at mid frequencies. Obviously leakage into the stage booms from a
pit or off-stage orchestra is always
severe. It is a psychological fact
that musicians always play twice
as loudly on air as in rehearsal,
ruining a carefully set balance via
pickup on the booms. In addition,
ambient set noise is aggravated
by spacious acoustics, particularly so in theater studios.
The newer dynamic cardioid and
line microphones make a tremendous difference in handling these
problems. Front/back ratio has been increased and made quite
uniform over a wide frequency
range. Leakage in the old sense of
the word is minimized, and working distances may be substantially
increased. Of course, the boom operator must be more alert in positioning the mic, because of the
increased directivity. Not the
least of the advantages gained are
mechanical ruggedness and freedom from shock, plus reduction of
proximity effect.
Control Engineer's Cue Sheet
With the physical setup of the
board arranged so that the most
important mics are centered
among the pots, and the possible
boom microphone problem alleviated, the next important consideration is some means of "prodding" the engineer's memory during the course of a long show.
Memory serves an important
function because levels must be
constantly adjusted on cue
throughout the show, and critically changed to adapt to vocal entrances, dynamic orchestra levels,
and commercials. For live shows,
the audio control man has only
one chance to do the mixing job
correctly.
Because the average popular
musical number runs only 3 to 4
minutes, memory is hardly overtaxed with regard to vocal cues or
relative mixing levels. However,
memory certainly needs regular
jogging during the course of a
long show involving many numbers, several commercials, and
much repositioning of the booms,
not to mention prerecorded sections, film spots, etc. Cue sheets
and notes on the script are very
necessary. The most important
level changes and cues are in the
transition from one musical number to another. As the announcer
or performer takes over the boom
at the conclusion of a number, the
orchestra mies and other important mic pots must be reset for
the start of the next number. They
may need closing down (but not
off) during announcements in order to hold down set noise, but
must be quickly and accurately
reset for most effective levels at
the start of the next number.
Fig. 3 illustrates a simple
shorthand method of marking a
script or musical cue sheet so as
to leave no doubt about proper pot
settings. A rectangle with arrows
represents the important mixer
pots concerned with orchestra accompaniment. The circles represent the two boom mies. While
this notation is correct for rotary
pots only, a variant will easily
suggest itself for those studios fortunate enough to employ vertical,
slide-type mixing pots in their
consoles.
Relative settings of all the important pots are shown at a glance
by the arrow positions. If the engineer is supplied with song word
sheets, important level changes
can be shown throughout by
quickly sketching in the rectangle
and arrows during rehearsals. The
arrows are best interpreted as set
at the hours of the clock; the actual engraved dial setting is unimportant. If the boom pots need
critical adjustment at the same
time as orchestra pot changes, simply add the circles to the right of
the rectangle, and write in the
name of the person the boom is
on at the time.
With the hands so busy with
mixing, a foot-switch of the type
used with certain home appliances
can be an asset to a busy engineer.
This switch should be tied in parallel with the talk-back or boomcue key on the console, so that the
boom operators can be cued in at
important transitional points during the show, and without having
to release a hand to operate the
key. The addition of the footswitch can do wonders for the
smoothness of boom positioning,
since communications with the operators is instantly available without fear of jeopardizing other
mixing chores.
Familiarity with Music Helps
While a good memory is an important factor in mixing of any
kind, let us stress that an understanding of music is the most valuable asset an engineer can have,
since so much of today's mixing
is directly concerned with broadcasting music. There is nothing
to be gained by assigning an engineer who normally spends his
scheduled hours handling dramatic shows, telecine cut-ins, or
news shows to a big musical extravaganza, unless he is musically
competent. A man who knows music will have a feeling for what is
coming next, even if he is not familiar with a particular number,
and he can automatically anticipate dynamic level changes and
vocal entrances.
cal entrances.
In the pickup of a symphony
orchestra on TV, the word mixing
is almost a misnomer, since fewer
mics are used in an ideal setup.
The less the manipulation of themic pots, the more natural the
dynamic realism, assuming room
acoustics are a help and not a
hindrance. Touching up accent
mics to go with changes in camera shots may be necessary and
should not be ignored. There is
nothing worse to a classical music
lover than to see a close-up of the
woodwind section and to hear the
incongruous sound of an overall,
distant pickup. If the audio engineer cannot follow a score, the
production personnel should see
that he is cued in ahead of the
camera switch.
By contrast, popular music mixing techniques continually call for
compression of the dynamic range,
and the general musical balance
is, to a considerable extent, taken out of the hands of the musical
conductor and placed in the hands
of the studio engineer. If he is
astute, the relative levels between
accompaniment, vocalists, and announcers are kept uniform, without
obliteration of one by the other,
and as a bonus, the radiated power
at the transmitter is commercially
efficient. A second method of dynamic range compression involves
the well-known but improperly understood compression amplifier.
Since the use of such a device
brings up certain other system
philosophies and problems, however, suffice it to say that the
newer, slow-attack, medium-recovery compressors are best suited for regular studio use. Fast-attack, shelving-curve compressors
belong in the transmitter, serving
as peak compression units.