THE SOUND OF THE PROFESSIONALS@
PROFESSIONAL PRODUCTS
GENERAL
The Shure Model SM80 is a high-quality, omnidirec-
tional condenser microphone designed for the most
demanding professional applications in studio record-
ing, broadcasting and sound reinforcement. It is
especially suitable for applications requiring extremely
wide frequency response, low noise and distortion
characteristics, very low RF susceptibility, and reliable
operation over a wide range of temperature and humid-
ity extremes. The SM80 features a selectable 10 dB
attenuator and a three-position low-frequency response
switch. The case is constructed of steel for ruggedness,
with a stainless steel screen, and finished in durable
vinyl paint.
The SM80 is designed for phantom (simplex) power-
ing from an external supply such as the Shure Model
PS1A, or directly from recording, broadcast or sound
reinforcement equipment. The SM80 operates over a
wide voltage range covering both DIN Standard 45 596
phantom voltages of 12 and 48 volts.
SPECIFICATIONS
The microphone is supplied with a highly efficient
pop filter grille (Model A81G), attenuator lock, and
swivel adapter. Also available for use with the SM80 are
a unidirectional microphone cartridge (Model R104), a
heavy-duty windscreen (Model A81WS), and a compact,
lightweight microphone stand (Model S15) capable of
being extended to 4.3m (14 ft). A dual-channel power
supply (Model PS1A) is available for providing phantom
power to the SM80.
Type
Omnidirectional condenser (electret bias)
Frequency Response
20 to 20,000 Hz (see Figure 1)
n Wide-range frequency response for exceptionally
accurate recording and sound reinforcement appli-
cations
n Low noise and high output clipping level char-
acteristics
TYPICAL FREQUENCY RESPONSE
n
Low distortion characteristics over the entire audio
spectrum for a wide range of load impedances
FIGURE 1
Polar Pattern
n
Omnidirectional polar pattern is equally sensitive to
sounds from all directions
Omnidirectional (see Figure 2)
n
Very low RF susceptibility
n
Selectable low-frequency response: flat, 6 or 18
dB/octave rolloff
n
n
10 dB attenuator accessible without disassembly;
lockable in either position
Wide-range phantom powering includes DIN 45 596
voltages of 12 and 48 Vdc
n Rugged construction for outstanding reliability
n
Field-usable over wide range of temperature and
humidity conditions
VARIATIONS
TYPICAL POLAR PATTERNS
FIGURE 2
Model SM80-LC: Supplied less cable.
Copyright 1986, Shure Brothers Incorporated
27A1743(FF)
Printed in U.S.A.
Patent Pending
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Case
Output Impedance
Steel construction with metallic vinyl paint finish and
stainless steel screen
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)
Dimensions
See Figure 3
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)
OVERALL DIMENSIONS
FIGURE 3
800-ohm Load
150-ohm Load
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
- 4 dBV (0.63V)
- 15 dBV (0.18V)
Weight
Net
Total Harmonic Distortion
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
230 grams (8 oz)
1.2 kg (2 lb 10 oz)
Less than 0.5% (132 dB SPL at 250 Hz into 800-ohm
load)
Packaged
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maximum SPL (at 1,000 Hz)
137 dB (attenuator at 0); 147 dB (attenuator at 10)
with 800-ohm load
*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.
129 dB (attenuator at 0); 139 dB (attenuator at 10)
with 150-ohm load
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.
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
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.
Pins 2 and 3 with Respect to Pin 1
Reverse Polarity Protection . . . . . . . . . . . . . . . . . . . . . . 200 mA max.
. . . . . . . . . . . . . . . . . . + 52 Vdc
(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)
-29° to 57°C
(-20° to 135°F)
Relative Humidity 0 - 95%
. . . . . . . . . . . . . . . . . . . . . . .
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
Connector
Professional three-pin audio**
2
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ohms, but a reduction in output clipping level will result.
It should be noted that the power supply itself may add
loading (3300 ohms in the Shure PS1A Power Supply) to
the microphones.
RESISTOR R VALUES
FIGURE 7
ISOLATION NETWORK
better to assure close matching, although the absolute
value is not critical. Note that the two-resistor phantom
power supply (Figure 5) presents a load equal to 4R,
paralleled with the mixer input impedance, to the SM80.
If the combined parallel load is below 800 ohms, the
transformer configuration (Figure 6) is recommended,
and if the combined load is 150 ohms or less, it must be
used.
If the power supply is unregulated, the power supply
voltage may drop when the SM80 is connected to it, due
to the added load. To account for this load, the value of
R may be determined as follows. Connect a variable
resistance (or resistor substitution box) in series with a
10-kilohm, 10% resistor. Connect the free end of the 10k
resistor to ground and the free end of the variable
resistor to B + of the power supply. Adjust the variable
resistor until 12 to 36 volts is measured across the 10k
resistor. Note the actual dc supply voltage and the value
of the variable resistor. Verify that the resistor value
falls with the indicated range on the graph of Figure 7.
The value of the variable resistor is the appropriate
resistance R for use in Figure 6. If the configuration in
Figure 5 is to be used, double the resistor value (2R).
Voltages as low as 10 Vdc minimum as measured at the
microphone connector are acceptable. The nominal cur-
rent drain at 10 Vdc is 1.1 mA. This is the minimum cur-
rent a power supply must be able to deliver for proper
operation.
FIGURE 4
PS1A POWER SUPPLY
Connect the microphone cable to the SM80 and the
power supply MICROPHONE connector. The power sup-
ply uses the balanced audio cable pair to carry the sup-
ply current to the microphone, and the cable shield as a
ground return.
Connect the power supply OUTPUT connector to a
low-impedance microphone input of the mixer, audio
console or tape recorder. A second SM80 may be con-
nected to the remaining power supply channel in a
similar manner.
ALTERNATE POWER SOURCES
As an alternate to the PS1A power supply, the SM80
may be phantom-powered from virtually any mixer,
audio console or tape recorder using one of the wiring
configurations shown in Figures 5 and 6. Any well-
filtered voltage available in the mixer from 12 to 48 Vdc
may be used. The graph in Figure 7 shows the range of
values which can be used for resistor R when the SM80
is used with a regulated power supply. The tolerance of
the resistors (2R) shown in Figure 5 should be 1% or
For example, in mixers with 30 Vdc power supplies,
the value of 2R for the configuration in Figure 4 could be
3.6k. Two 3.6k resistors should be closely matched (2%
or better), and may be mounted externally with the B +
end connected to the 30V terminal. The resistors may
also be mounted internally (such modifications should
be performed by qualified service personnel only).
A convenient method of battery-powering the SM80
using two 9-volt batteries is shown in Figure 8. Note
TWO-RESISTOR CONFIGURATION
FIGURE 5
CENTER-TAPPED TRANSFORMER
CONFIGURATION
BATTERY POWER SUPPLY
FIGURE 8
FIGURE 6
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input. A resistive attenuator can be inserted in the
microphone line ahead of the mixer to minimize this.
The Shure Model A15AS Attenuator (15, 20 or 25 dB
switch selectable) is specially designed for use with
condenser microphones. A convenient 15 dB attenuator
design is shown in Figure 9. The resistors shown are
1/2-watt, 1% tolerance, and the circuit may be pack-
aged in a Switchcraft S3FM adapter housing. The 15 dB
attenuator can be used between the SM80 and the PS1A
(or other power supply), or between the PS1A and the
mixer. Two of these attenuators may be used in series
to provide 30 dB of attenuation. Note that commercially
available 150-ohm attenuators (such as the Shure Model
A15A) are not recommended, due to loading.
that this circuit can on/y be used with balanced, floating
(ungrounded), transformer-coupled input mixers such
as the Shure M67 or SE30. The resistors should be 1%
tolerance or better to assure close matching. With new
batteries, this supply will operate an SM80 for approx-
imately 200 hours.
LOW-FREQUENCY RESPONSE SWITCH
The SM80 has a three-position low-frequency
response switch located on its handle. The switch is
recessed to avoid accidental movement, but may be
easily moved with the fingertips. The user may select
either flat response, low-frequency rolloff of 6 dB per oc-
tave below 100 Hz, or low-frequency cutoff of 18 dB per
octave below 80 Hz (see Figure 1).
ATTENUATOR RING
The SM80 has a switchable 10 dB capacitive atten-
uator to prevent high sound pressure levels from over-
loading the microphone’s internal electronics. The
attenuator is engaged by rotating the actuator ring
directly below the grille assembly. In the “10” position,
the output of the microphone is reduced by 10 dB, in-
creasing the maximum sound pressure level at clipping
by 10 dB.
The attenuator ring may be locked in either the “0” or
“10” position as follows. Unscrew the grille and car-
tridge assembly by unscrewing counterclockwise from
the top. Turn the actuator ring to the “0” or “10” position
as desired. Insert the actuator ring lock (small curved
piece of plastic) in the area behind the actuator ring be-
tween the pin and the edge of the slot, thereby preven-
ting the ring from turning. Replace the grille and car-
tridge assembly.
The amount of attenuation can be increased by
changing the value of the capacitor in the 10 dB at-
tenuator switch assembly. Note that this change must
be done carefully and with subsequent cleaning to
avoid possible signal-to-noise degradation. Unscrew
the grille and cartridge assembly (counterclockwise
from top). Lift the 10 dB attenuator actuator ring up and
over the screw threads. Grasp the center contact of the
10 dB attenuator switch assembly and lift upward to
remove it. Obtain a 5% NPO monolithic ceramic
capacitor (Centralab MONO-KAP CN series or
equivalent) of the required value for the desired attenua-
tion:
15 dB ATTENUATOR CIRCUIT
FIGURE 9
WIND NOISE
The excellent frequency response of professional
condenser microphones such as the SM80 makes them
quite sensitive to wind, breath and air currents from ven-
tilation equipment. The resulting low-frequency micro-
phone output may cause mixer overload or other prob-
lems. The Model A81G Pop Filter Grille attenuates
breath popping sounds when the microphone is close-
talked, and permits its use outdoors with minimal
pickup of rushing and rumbling sounds.
Slip the A81G over the SM80 until the inside of the
A81G touches the top of the microphone. Tighten the
A81G by rotating the knurled collar clockwise from the
bottom. When removing the A81G, loosen the knurled
collar first (otherwise the cartridge will unscrew with
the A81G).
For outdoor use under very windy conditions, the
Model A81WS Heavy-Duty Windscreen is recom-
mended.
Attenuation
-15 dB
Capacitance
150 pF
CIRCUIT DESCRIPTION
-20 dB
270 pF
A block diagram of the SM80 is shown in Figure 10.
The capacitor cartridge is followed by a switch-con-
trolled capacitive attenuator stage which provides for
10 dB attenuation at the cartridge output. The signal is
fed to a field-effect transistor (FET) impedance con-
version stage. The FET output drives an active low-
frequency response (high-pass) filter controlled by a
three-position switch. The filter output from a com-
pound transistor, Class A, emitter-follower amplifier is
transformer-coupled, providing a balanced output to the
RFI protection filter at the microphone connector. An
active, constant-current power supply circuit regulates
the phantom voltage, allowing the SM80 to operate over
a very wide range of voltages. A reverse voltage protec-
tion diode guards against miswired cables and equip-
ment. The circuit contains five semiconductors to pro-
vide low noise, low distortion, wide frequency response
and ultra-reliable operation over a very wide range of
operating conditions.
-25 dB
-30 dB
560 pF
.001 µF
Using long-nose pliers and a low-wattage, pencil-type
soldering iron, carefully remove the capacitor from the
switch assembly and replace it with the new value. Take
care not to touch the switch assembly with the solder-
ing iron. To remove possible contamination, after
soldering wash the entire switch assembly in a mild
detergent solution, rinse it in distilled water, soak it in
alcohol to remove the water, and allow it to air dry.
Reassemble the SM80. Note the new attenuation value
on the SM80 attenuator ring with a small label.
MIXER OVERLOAD
The SM80 output is about 15 dB higher than most
dynamic microphones, in order to provide optimum
signal-to-noise ratio. When used at moderate to high
SPLs, this additional output may overload the mixer
4
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BLOCK DIAGRAM
FIGURE 10
frequency response switch and a lockable 10 dB at-
tenuator pad.
SERVICING
TROUBLESHOOTING
The overall dimensions shall be 212 mm (8-11/32 in.)
in length by 23.5 mm (15/16 in.) in diameter. The handle
diameter shall be 20.1 mm (25/32 in.). The weight shall
be 230 grams (8 oz).
The microphone shall be capable of being powered by
a phantom (simplex) power supply with an output of 11
to 52 Vdc, or by a mixer, audio console or tape recorder
capable of supplying 11 to 52 Vdc.
Due to the high packing density and circuit com-
plexity of the SM80, only basic servicing is recom-
mended. The following steps should be taken if
problems arise.
1. Check the power supply output voltage to the
microphone. For the Shure PS1A, this should be 21.5
± 1.5 Vdc open circuit.
2. Check the voltage on microphone connector pins 2
and 3 (at back of connector; cable connector
disassembled from shell but connected to micro-
phone). The voltage at pins 2 and 3 with reference to
pin 1 should be between 10 and 48 Vdc.
The microphone shall be a Shure Model SM80.
FURNISHED ACCESSORIES
Pop Filter Grille
Swivel Adapter
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A81G
A57D
10 dB Attenuator
34A830
Lock
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.
If more than one SM80 is available, interchange car-
tridge assemblies to determine whether the car-
tridge or amplifier is at fault.
OPTIONAL ACCESSORIES
Unidirectional
Phantom Power
Microphone Cartridge
. . . . . . . . . . . . . . . . . . . . . . .
R104
PS1A
Supply
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Heavy-Duty Windscreen
Tripod Microphone Stand (4.3m - 14 ft) . . . . . . . . . . . . . . . . . . . . . S15
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A81WS
DISASSEMBLY
The SM80 can be disassembled as follows:
1. Unscrew the grille and cartridge assembly (coun-
terclockwise from top).
2. Lift the 10 dB attenuator actuator ring up and over
the screw threads.
3 . Grasp the center contact of the 10 dB attenuator
switch assembly and lift upward to remove it.
4 . Turn the slotted head screw near the plug coun-
terclockwide (inward) as far as it will go. Using a
long-nose pliers, grasp one pin of the three-pin con-
nector and withdraw the RFI filter and plug element
from the handle.
Cable (7.6m [25 ft],
XLR connectors) . . . . . . . . . . . . . . . . . . . . . . . . C25F
REPLACEMENT PARTS
Grille and Cartridge Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R104A
10 dB Attenuator Actuator Ring
10 dB Attenuator Switch
Low-Frequency Response Switch Knob . . . . . . . . . . 65A1218A
PC Board Assembly and Support . . . . . . . . . . . . . . . . . . . . . . . . 90B3820
. . . . . . . . . . . . . . . . . . . . . . . . 31B1334B
Assembly
. . . . . . . . . . . . . . . . . . . . .
90B2883
Handle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31B1392B
90A3622
RFI Filter and
Plug Element
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GUARANTEE
5. Remove the low-frequency response switch knob by
placing a small screwdriver or tweezers into the slot
under the ridge of the knob and lifting outward.
6 . Remove the small Phillips screw near the plug. Tap
the cartridge end of the handle gently on a firm sur-
face; the printed circuit board and support assembly
will slide out of the cartridge end.
This Shure product is guaranteed in normal use to be
free from electrical and mechanical defects for a period
of one year from date of purchase. Please retain proof
of purchase date. This guarantee is in lieu of any and all
other guarantees or warranties, express or implied, and
there shall be no recovery for any consequential or in-
cidental damages.
SHIPPING INSTRUCTIONS
Carefully repack the unit, insure it, and return it
prepaid to:
ARCHITECTS’ SPECIFICATION
The microphone shall be a condenser microphone
with a frequency response of 20 to 20,000 Hz. It shall
have an omnidirectional pickup characteristic. The
microphone shall have a rated output impedance of 150
ohms for connection to microphone inputs of 150 ohms
or higher. The open circuit voltage shall be -65 dB (0.56
mV) (0 dB equals 1 volt per microbar).
Shure Brothers Incorporated
Attention: Service Department
222 Hartrey Avenue
Evanston, Illinois 60202-3696
If outside the United States, return the unit to your
dealer or Authorized Shure Service Center for repair.
The unit will be returned to you prepaid.
The microphone shall contain a three-position low-
5
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