Model SM81 User Guide
Shure
Brothers Incorporated
222 Hartrey A
venue
Evanston IL 60202-3696 U.S.A.
27A2916
(P
A)
1996, Shure Brothers Inc.
Printed in U.S.A.
MODEL SM81
UNIDIRECTIONAL CONDENSER MICROPHONE
The Shure Model SM81 is a high-quality, unidirectional
condenser
microphone designed for the
most demanding pro
-
fessional applications in studio recording, broadcasting, and
sound
reinforcement. It is especially suitable
for applications re
-
quiring
extremely wide frequency
response, low noise and dis
-
tortion characteristics, very low RF susceptibility, and reliable
operation over a wide range of temperature and humidity
extremes.
The case is constructed
of steel for ruggedness, with
a stainless steel screen, and finished in durable vinyl paint.
The microphone is furnished with a swivel adapter, atten-
uator lock, windscreen, and carrying/storage case. It is sup-
plied
without cable. A
vailable accessories are a highly ef
ficient
pop-filter
grille (Model A81G), a heavy-duty windscreen (Model
A81WS), a compact, lightweight microphone stand (Model
S15)
capable of extension to 4.3 m (14 ft), a versatile stereo mi
-
crophone
adapter (Model A27M), and a dual-channel phantom
power supply (Model PS1A). An alternative omnidirectional
cartridge (Model R104A) is also available.
Model SM81 Features:
•
Wide-range, frequency response for exceptionally accu-
rate recording and sound reinforcement applications
•
Low noise and high output clipping level characteristics
•
Low distortion characteristics over the entire audio spec-
trum for a wide range of load impedances
•
Cardioid polar pattern, uniform with frequency and sym-
metrical about axis, to provide maximum rejection and
minimum coloration of off-axis sounds
•
Very low RF susceptibility
•
Selectable
low-frequency response: flat, 6 or 18
dB/octave
rolloff
•
10 dB attenuator accessible without disassembly; lockable
in either position
•
Wide-range phantom powering includes DIN 45 596 volt-
ages of 12 and 48 Vdc
•
Rugged construction for outstanding reliability
•
Field-usable
over wide range of temperature and
humidity
conditions
SPECIFICATIONS
Type
Cardioid
Frequency Response
20 to 20,000 Hz (see Figure 1)
TYPICAL FREQUENCY RESPONSE
FIGURE 1
Polar Pattern
Cardioid
(unidirectional) response—uniform with frequen
-
cy, symmetrical about axis (see Figure 2)
TYPICAL
POLAR P
ATTERNS
FIGURE 2
Output Impedance
Rated at 150 ohms (85 Ω actual)
Recommended minimum load impedance: 800 Ω (May
be used with loads as low as 150 Ω with reduced clip-
ping level)
Output
Level (at 1,000 Hz)
Open Circuit Voltage –65 dB (0.56 mV).
. . . . . . . . . . . . . . . .
(0 dB = 1 volt per µbar)
Equivalent Power Level –40.5 dB.
. . . . . . . . . . . . . . . . . . . . .
(0 dB = 1 milliwatt per 10 µbars)
Clipping
Level (at 1,000 Hz)
800 Ω Load –4 dBV (0.63 V).
. . . . . . . . . . . . . . . . . . . . . . . . .
150 Ω
Load
–15 dBV (0.18 V).
. . .
. . . . . . . . . . . . . . . . . . . .
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General
Weight and Dimensions
