Shure SM81 User Manual

MODEL SM81 UNIDIRECTIONAL
CONDENSER MICROPHONE
The Shure Model SM81 is a high-quality, unidirectional con-
denser microphone designed for studio recording, broadcasting,
and sound reinforcement. Its wide frequency response, low noise
characteristics, and low RF susceptibility have made it a standard
for applications involving acoustic instruments, especially guitar,
piano, and cymbals.
The SM81 is ruggedly constructed. It operates on phantom pow-
er and performs over a wide range of temperatures and humidity
conditions. It is furnished with a swivel adapter, attenuator-switch
lock, foam windscreen, and case for carrying and storage. Other
accessories are available.

Model SM81 Features

• 20 Hz to 20 kHz frequency response
• Flat response curve for accurate reproduction of sound
sources
• Low noise and high output clipping level
• Low distortion over a wide range of load impedances
• Cardioid polar pattern, uniform with frequency and sym-
metric about axis, providing maximum rejection and min-
imum coloration of off-axis sounds
• Low RF susceptibility
• Selectable low-frequency response: flat, 6 or 18 dB/oc-
tave rolloff
• 0 dB/10 dB lockable attenuator switch
• Phantom powering (DIN 45 596 voltages of 12 to 48 Vdc)
• Rugged steel construction for durability
• Field-usable over wide range of temperature and humidi-
ty conditions
2005, Shure Incorporated
©
27C2916 (Rev. 6)
Model SM81 User Guide

SPECIFICATIONS

Type
Condenser (electret bias)
Frequency Response
20 to 20,000 Hz
+20
+10
0
–10
-20
2
20 50 100
TYPICAL FREQUENCY RESPONSE
FIGURE 1
Polar Pattern
Cardioid (unidirectional) response-uniform with frequency, sym-
metrical about axis
180°
150°
150°
120°
120°
90°
–20 dB –20 dB
–15 dB
–15 dB
60°
–10 dB
–10 dB
–5 dB
–5 dB
30°
30°
0
1000 Hz
500 Hz
100 Hz
TYPICAL POLAR PATTERNS
FIGURE 2
Output Impedance
Rated at 150 Ω (85 Ω actual)
Recommended minimum load impedance: 800 Ω (May be used
with loads as low as 150 Ω with reduced clipping level)
Output Configuration and Connector
Balanced, transformer-coupled output; male XLR connector
Sensitivity (at 1,000 Hz)
Open Circuit Voltage: . . . . . . . . . . . . –45 dBV/Pascal (5.6 mV)
(1 Pascal = 94 dB SPL)
Clipping Level (at 1,000 Hz)
800 Ω Load: . . . . . . . . . . . . . . . . . . . . . . . . . . –4 dBV (0.63 V)
150 Ω Load: . . . . . . . . . . . . . . . . . . . . . . . . . –15 dBV (0.18 V)
Total Harmonic Distortion
Less than 0.5% (131 dB SPL at 250 Hz into 800 Ω load)
1 METER
3 4 5 6 7 9 8 2 3 4 5 6 7 9 8
1000 10000
Hz
180°
150°
120°
90° 90°
–20 dB –20 dB
–15 dB
–15 dB
60°
60°
–10 dB
–10 dB
–5 dB –5 dB
30°
0
2000 Hz
5000 Hz
10000 Hz
Printed in U.S.A.
20000
150°
120°
90°
60°
30°