Shure SM91A, User Manual

Page: 2 / 5

2.
SPECIFICATIONS
Type
Cardioid condenser (electret bias) for surface mounting
Frequency Response
20 to 20,000 Hz (see Figure 1)
TYPICAL FREQUENCY RESPONSE
(measured at 30
o
incidence to infinite surface)
FIGURE 1
Polar Pattern
Half-cardioid (cardioid in hemisphere above mounting
surface), uniform with frequency, symmetrical about
axis (see Figure 2)
TYPICAL POLAR PATTERN
FIGURE 2
Output Impedance
Rated at 150
Ω
(90
Ω
actual)
Recommended minimum load impedance: 800
Ω
(May be used with loads as low as 150
Ω
with reduced
clipping level)
Output Level (at 1,000 Hz, measured with sound source
at 30
o
incidence to flat surface)
Open Circuit Voltage –71.5 dB (0.27 mV) . . . . . . . . .
0 dB = 1 V
/µ
bar
Preamplifier Output Clipping Level (at 1,000 Hz, less
than 0.1% THD)
GAIN
0 +10
800
Ω
load 0 dBV –7.0 dBV . . . . . . . . . . . . . . .
(1.0 V) (0.45 V)
150
Ω
load –13.0 dBV –21.0 dBV . . . . . . . . . . . . . .
(0.22 V) (0.09 V)
Maximum SPL (at 1,000 Hz, less than 1% THD)
800
Ω
load
ILP-1 gain set at 0 dB 146.5 dB . . . . . . . . . . . . . .
ILP-1 gain set at +10 dB 136.5 dB . . . . . . . . . . .
150
Ω
load
ILP-1 gain set at 0 dB 129.5 dB . . . . . . . . . . . . . .
ILP-1 gain set at +10 dB 118.5 dB . . . . . . . . . . .
Electromagnetic Hum Pickup (maximum)
–0.5 dB equivalent SPL in 1 mOe field (60 Hz)
Preamplifier Controls
Selectable Low-Frequency Response: Flat/Low Cut
(12 dB/octave rolloff below 80 Hz)
Selectable Gain: 0/+10 dB
Output Noise
25.5 dB SPL, A-weighted
32 dB SPL, C-weighted
28.5 dB SPL per DIN 45 405
Signal-to-Noise Ratio
68.5 dB re 94 dB SPL
Dynamic Range
121 dB (800
Ω
load, gain set at 0 dB)
Phasing
Positive pressure on diaphragm produces positive volt-
age on pin 2 relative to pin 3 of preamp output connector
Power
11 to 52 Vdc phantom (simplex) voltage (operational
down to 9 Vdc with reduced clipping level); current
drain 2.2 mA at 52 Vdc, 1.8 mA at 11 Vdc
Case
Microphone: Matte black enamel die-cast base and
perforated steel grille with replaceable or cleanable
fine mesh screen and foam pad wind/dirt barrier
Preamplifier: Matte black enamel finished steel
Cable
7.6 m (25 ft) two-conductor shielded, small diameter,
with Switchcraft Tini (Q.G.) 3-pin (female) connector
on each end
Environmental Conditions
Operating Temperature: –18 to 57
o
C (0 to 135
o
F)
Storage Temperature: –29 to 74
o
C (–20 to 168
o
F)
Relative Humidity: 0 to 95%
Dimensions
See Figure 3
OVERALL DIMENSIONS
FIGURE 3