Shure SM81 User Manual

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. Available accessories are a highly efficient
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
1996, Shure Brothers Inc.
27A2916 (PA)
Shure Brothers Incorporated
222 Hartrey Avenue
Evanston IL 60202-3696 U.S.A.
Model SM81 User Guide
SPECIFICATIONS
Type
Cardioid
Frequency Response
20 to 20,000 Hz (see Figure 1)
TYPICAL FREQUENCY RESPONSE
Polar Pattern
Cardioid (unidirectional) response—uniform with frequen-
cy, symmetrical about axis (see Figure 2)
TYPICAL POLAR PATTERNS
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 . . . . . . . . . . . . . . . . .
Equivalent Power Level
Clipping Level (at 1,000 Hz)
800 Ω Load
. . . . . . . . . . . . . . . . . . . . . . . . . .
150 Ω Load
. . . . . . . . . . . . . . . . . . . . . . . .
FIGURE 1
FIGURE 2
–65 dB (0.56 mV)
(0 dB = 1 volt per µbar)
. . . . . . . . . . . . . . . . . . . . . .
(0 dB = 1 milliwatt per 10 µbars)
–4 dBV (0.63 V)
–15 dBV (0.18 V)
Printed in U.S.A.
–40.5 dB