RCA 77-A, Instructions Manual

there is a tendency toward accentuation of low frequencies,
which may result in making voices sound “boomy.” In this re-
spect the use of the uni-directional microphone differs greatly
from that of the condenser microphone, with which the soloist
usually works at a distance of from 4 to 6 inches. As a point of
useful information, it may be mentioned here that the uni-di-
rectional microphone may be used as a close-talking micro-
phone by talking in the plane of the ribbon. In this position, only
the pressure-operated part of the ribbon is used.

e placement of a speaker or musical instrument off from the

center line of the microphone will in no way affect the quality
of pick-up, but will merely attenuate the direct sound pick-up,
thereby raising the ratio of reverberation to direct pick-up.

e microphone is uni-directional. Speakers, instruments or

players may be placed on the operating side of the microphone
only. e diagrams (Figures 5, 6, 7, and 9) will serve as examples
which arise from the uni-directional characteristic.

For more satisfactory results, the microphone should not be

placed closer than 3 feet to any solid reflecting surface. is
statement is, of course, general and specific conditions may re-
quire otherwise.

e diagrams referred to in the subsequent paragraphs and

the discussion concerning them can only serve to indicate some
of the possible placements under particular conditions. e
final decision as to what constitutes the proper placement must
rest with someone who is competent to judge the quality of the
results as reproduced by the monitor speaker.

(b) Soloist with Piano.

—Interesting effects may be obtained

by changing the angle of the microphone with respect to the
piano, thus changing the ratio of reverberation to direct pick-
up.  e  distance  between  the  soloist  and  the  microphone
should be determined by the strength of his (or her) voice, and
the piano should be placed accordingly. e general arrange-
ment  is  shown  in  Figure  5.  Under  no  condition  should  the
soloist be less than 2 feet from the microphone.

(c) Stage Plays.

—In the case of stage plays and those pick-ups

of the type that occur in the case of auditorium-type studios,
where a sizeable audience is present—and in remote pick-ups
at theatres, night clubs and the like, where audience noise is a
serious  problem,  the  use  of  the  uni-directional  microphone
possesses a distinct advantage. By placing the microphone with

its dead side toward the audience and close to the footlights, or
in an equivalent position, the 20-dB discrimination will provide
the desired attenuation of audience noise, while the broad pick-
up angle—useful through nearly 150 degrees—will afford pick-
up of the whole stage, or that part of the studio where the artists
are located. See Figure 6.

(d) Dance Orchestra.

—e set-up for dance orchestra is sim-

ilar to that just outlined for stage plays, the dead side of the uni-
directional  microphone  being  toward  the  dance  floor.  e
diagram (Figure 7) is self-explanatory, the only precaution nec-
essary being to keep the soloist at least 2 feet, and preferably 3
feet, from the microphone.

In locating the microphone with respect to an orchestra, care

should be taken to avoid reflected pick-up from hard-surfaced
floors. Such reflections can be avoided by the use of carpets or
similar material on the floor.

(e) Large Orchestra.

—An arrangement for a large symphony

orchestra is shown in Figure 9. It is to be noted that the wide
angle of coverage (150 degrees) of the uni-directional micro-
phone will permit a satisfactory pick-up in many cases, such as
that  shown,  with  but  one  microphone.  It  must  be  borne  in
mind,  however,  that  the  physical  proportions  and  acoustic
properties of the studio have a direct bearing on the arrange-
ment of the orchestra and placement of the microphone. Where
space considerations do not govern, changes from the arrange-
ment shown should not necessarily be very extensive in order
to give excellent results under the usual acoustic conditions.

(f ) Public Address.

—For public address use, the microphone

can usually be placed near the loudspeakers (within 3 or 4 feet).
It is important to see that the dead side of the microphone is to-
ward the loudspeaker system—more specifically, the micro-
phone  should  not  be  placed  in  front  or  directly  behind  the
loudspeakers to prevent acoustic feedback. If the speaker must
have latitude of movement on the stage, it may be necessary to
have a microphone installed at each side to obtain satisfactory
pick-up.

(g) Sound Reenforcing.

—Microphones used for this purpose

must generally be concealed and may be successfully operated
in the wings, flys, etc., or at the front of the stage, where some
simple method may be devised for their concealment. Such a
system usually requires the use of a number of microphones

Figure 5—Soloist with Piano

Figure 6—Plays

Figure 7—Dance Orchestra

VARIOUS MICROPHONE ARRANGEMENTS