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UNIDIRECTIONAL DYNAMIC MICROPHONES
\ '
General:
The Model
581
Series Unidyne
A
Micro-
phones are moving coil dynamic units built t o provide
excellent reproduction of music and voice and t o feature
an exceptionally good unidirectional microphone pickup
pattern.
These microphones are particularly suitable for use in
theatres, night clubs, auditoriums, schools, churches, and
any place where ordinary microphones may not operate
properly because of poor acoustics. These microphones
will in almost every instance eliminate the annoying
"squeals and howls" caused
by
feedback.
In addition,
they will prevent echoing (boominess) that sometimes
occurs in partially-filled halls.
These microphones can
also be used closer t o loudspeakers than usual, without
creating feedback problems.
This
suppression of feedback, combined with their
smooth sound, makes them particularly good for use with
orchestras, small combos, and singers.
In addition, the microphone features:
e
A
strong, easily disconnected cable, especially se-
lected because of i t s good shielding from "hum
pickup".
0
A n easily field-replaceable microphone cartridge.
A
cartridge that i s protectively shock-mounted
internally, which permits quieter handling.
A
built-in "on-off'' switch with a device t o lock
the switch in
i t s
"on" position.
A n adjustable swivel adapter that enables you t o
aim the microphone where you want
it.
A
plastic cushioned slot in the swivel that makes
it
easy t o quietly pull the microphone out and
use
it
comfortably in the hand.
The Model
581SA
i s high impedance for connection
into high impedance microphone inputs.
The Model
581SB
has a low impedance of
150
ohms and i s recommended where long cable lengths are
required, or where there are conditions of severe hum
disturbance.
To
use the Model
581SB
with a
high
im-
pedance amplifier, use a Shure Model
A95A
Line Match-
ing Transformer.
The Model
581SF
has a low impedance o f
25
ohms
and is designed for installations where lower impedances ,
are required.
The Model
58 I
SA-MP
is a set o f two matched Unidyne
A
Unidirectional Dynamic Microphones. The units are
matched within
1. 0
db
in level and within
1.5
db
for
frequency response.
For convenient connection t o most tape recorders,
standard phone plugs have been installed on the Model
58 I
SA-MP
microphone cables.
All
features, specifica-
tions, and performance data listed for the Model
58 I SA
apply t o the Model
581SA-MP
Microphones.
0
Models
581SB and 581SF
The matched Model
58
I SA
Microphones are primarily
intended for stereo recording or similar use.
Many
acoustic conditions affect the final placement o f micro-
phones during a stereo recording.
It
i s usually necessary
t o experiment with various locations of the microphones
t o achieve placement best suited t o your individual re-
quirements.
For pickup o f large groups,
it
may be
advisable t o raise the microphones above the performers
t o gain balance between front and rear of the group.
Model 581SA
SPEC1 FICATIONS
Type:
Dynamic
Frequency Response:
50
t o
12,000
HZ
(CPS)
Polar Pattern:
Cardioid (unidirectional) Response.
Uniform with frequency, symmetrical
about axis (See Figure
B)
Microphone
Rating
Impedance:
Model 58
I
SA
Model
581SB
150 ohms
High
Impedance
For connecting into microphone inputs rated at
50
t o 200 ohms
For connection into microphone inputs rated at
25
,to
50 ohms
'
Model 581SF
25
ohms
QUtpU* Level:
1000 H z
(cps) Response
Model
581SA
High
Impedance
Open circuit voltage
. _ _ . _ _ . _ _ _ _
-
56.5
db ( I
.48
mv]
EIA
Microphone Rating
G m (Sensitivity)
_...___..._._._-
I 52.5
d b***
Model 58
ISB
150 ohms Impedance
Open circuit voltage
_ . . _ _ _ _ _ _ _ _
-
79.5
db* (.
I05 mv)
Power Level
...._._...__..._____.....
-
57.0
db**
EIA
Microphone Rating
G m (Sensitivity)
I 5 1
.O db***
Copyright 1965, Shure Brothers, Inc.
27A357 (ME)
U.S. Patent 3,132,713. Other patents pending.
Printed in U.S.A.
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