Output Impedance
Rated at 150 ohms (85 ohms actual)
Recommended minimum load impedance: 800 ohms
(May be used with loads as low as 150 ohms with
reduced clipping level)
Output Level
(at 1,000 Hz)
Open Circuit Voltage . . . . . . . . . . . . . . . . . . . . . . . . -65 dB (0.56 mV)
(0 dB = 1 volt per microbar)
Equivalent Power Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40.5 dB
(0 dB = 1 milliwatt with 10 microbars)
Clipping Level
(at 1,000 Hz)
800-ohm Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - 4 dBV (0.63V)
150-ohm Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - 15 dBV (0.18V)
Total Harmonic Distortion
Less than 0.5% (132 dB SPL at 250 Hz into 800-ohm
load)
Maximum SPL
(at 1,000 Hz)
137 dB (attenuator at 0); 147 dB (attenuator at 10)
with 800-ohm load
129 dB (attenuator at 0); 139 dB (attenuator at 10)
with 150-ohm load
Hum Pickup
-4 dB equivalent SPL in a 1 millioersted field (60 Hz)
Output Noise
(equivalent sound pressure levels)
17 dB typical, A-weighted
20 dB typical, weighted per DIN 45 405
Signal-to-Noise Ratio
77 dB (IEC 179)* at 94 dB SPL
Overvoltage and Reverse Polarity Protection
Max. External Voltage Applied to
Pins 2 and 3 with Respect to Pin 1 . . . . . . . . . . . . . . . . . . + 52 Vdc
Reverse Polarity Protection . . . . . . . . . . . . . . . . . . . . . . 200 mA max.
(diode-clamped)
Phasing
Positive pressure on diaphragm produces positive
voltage on pin 2 relative to pin 3
Cartridge Capacitance
31 pF
LF Response Switch
Flat, -6 dB/octave below 100 Hz, -18 dB/octave
below 80 Hz
Attenuator Switch
0 or 10 dB (68 pF)
Power
Supply Voltage . . . . . . . 11 to 52 Vdc, positive pins 2 and 3
Current Drain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 mA to 1.2 mA
Environmental Conditions
Relative Humidity 0 - 50% . . . . . . . . . . . . . . . . . . . . . . . -29° to 74°C
(-20° to 165°F)
Relative Humidity 0 - 95% . . . . . . . . . . . . . . . . . . . . . . . -29° to 57°C
(-20° to 135°F)
Connector
Professional three-pin audio**
Case
Steel construction with metallic vinyl paint finish and
stainless steel screen
Dimensions
See Figure 3
OVERALL DIMENSIONS
FIGURE 3
Weight
Net . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230 grams (8 oz)
Packaged . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 kg (2 lb 10 oz)
*S/N ratio is difference between microphone output at 94 dB SPL and microphone
self-noise A-weighted.
**Designed to mate with Cannon XL series, Witchcraft A3 (Q.G.) series or
equivalent connectors.
OPERATION
The SM80 is designed for phantom powering by a
Shure Model PS1A Power Supply, or by virtually any
microphone power supply providing 12 to 48 Vdc phan-
tom voltage.
Use only high-quality cables, as intermittent shorts
between broken shield wires and balanced conductors
will cause extremely large noise transients in the
system. Avoid ground loops due to grounded connector
shells or the microphone case touching other grounded
metal objects. Follow generally accepted audio ground-
ing practices.
Paralleling or “Y-ing” the SM80 with another micro-
phone (two microphones on the same input) is not
recommended; separate inputs are preferable.
However, paralleling two SM80’s may be accomplished
with either a reduction in maximum SPL and output
level, or a reduction only in output level if the micro-
phones are electrically isolated. With the microphones
paralleled either before or after a PS1A Power Supply,
the maximum SPL is reduced by approximately 10 dB
and the output level by 6 dB. The reduction in maximum
SPL can be avoided by using either two Shure A15AS At-
tenuators and a Switchcraft 391Q43 Y-Adapter to
isolate the microphones, or an isolation network as
shown in Figure 4. The network reduces each micro-
phone output level by 8 dB, while the A15AS reduces the
output level by 5 dB plus the attenuator’s 15, 20 or 25 dB
(switch-selectable). The network or attenuators can be
inserted between the power supply outputs and mixer
input, or between two microphones and a single power
supply input. Note that a PS1A Power Supply can power
two SM80’s on each input; other power supplies should
be checked to see if they can supply a minimum of 10
Vdc at each microphone when both microphones are
connected.
A minimum load impedance of 800 ohms or greater
should be used for maximum signal handling and
minimum distortion. The load may be as low as 150
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