Advertisement
regulates the phantom voltage, and the 1.5-volt battery provides
regulates the phantom voltage, and the 1.5-volt battery provides
instantaneous backup in case the phantom power supply fails. The
instantaneous backup in case the phantom power supply fails. The
regulator/reverse voltage protector provides built-in protection
regulator/reverse voltage protector provides built-in protection
against miswired cables and equipment.
against miswired cables and equipment.
TROUBLESHOOTING
TROUBLESHOOTING
Due to the circuit complexity of the SM94, only basic servicing is
Due to the circuit complexity of the SM94, only basic servicing is
recommended. The following steps should be taken if problems
recommended. The following steps should be taken if problems
arise:
arise:
1. Check the power supply output voltage. For the Shure PS1A,
1. Check the power supply output voltage. For the Shure PS1A,
this should be 21.5, ±1.5 Vdc, open circuit.
this should be 21.5, ±1.5 Vdc, open circuit.
2. Check the voltage on connector pins 2 and 3 (at back of
2. Check the voltage on connector pins 2 and 3 (at back of
connector, with cable connector removed from shell, but
connector, with cable connector removed from shell, but
connected to microphone). The voltage at pins 2 and 3 with
connected to microphone). The voltage at pins 2 and 3 with
reference to pin 1 should be between 10 and 48 Vdc.
reference to pin 1 should be between 10 and 48 Vdc.
3. If the microphone does not work on phantom power, battery
3. If the microphone does not work on phantom power, battery
operation may still be possible. Similarly, if battery operation is
operation may still be possible. Similarly, if battery operation is
impaired, the SM94 may still operate on phantom power. In
impaired, the SM94 may still operate on phantom power. In
either case, you should send the microphone to an Authorized
either case, you should send the microphone to an Authorized
Shure Service Center at your earliest opportunity.
Shure Service Center at your earliest opportunity.
CAPACITOR
CAPACITOR
IMPEDANCE CONVERTER
IMPEDANCE CONVERTER
CARTRIDGE
CARTRIDGE
WITH ACTIVE LOAD
WITH ACTIVE LOAD
BATTERY
BATTERY
FET
FET
LF RESPONSE
LF RESPONSE
FILTER
FILTER
BLOCK DIAGRAM
BLOCK DIAGRAM
ARCHITECTS' SPECIFICATIONS
ARCHITECTS' SPECIFICATIONS
The microphone shall be a condenser microphone with a
The microphone shall be a condenser microphone with a
frequency response of 40 to 16,000 Hz. It shall have a cardioid
frequency response of 40 to 16,000 Hz. It shall have a cardioid
directional characteristic, with cancellation at the sides of 6 dB and
directional characteristic, with cancellation at the sides of 6 dB and
a minimum cancellation at the rear of 15 dB at 1 kHz. The
a minimum cancellation at the rear of 15 dB at 1 kHz. The
microphone shall have a rated output impedance of 150 Ω for
microphone shall have a rated output impedance of 150 Ω for
connection to microphone inputs of 150 Ω or higher. The open
connection to microphone inputs of 150 Ω or higher. The open
circuit voltage shall be –49 dBV/Pa (3.5 mV) dB equals 1 volt per
circuit voltage shall be –49 dBV/Pa (3.5 mV) dB equals 1 volt per
Pascal).
Pascal).
The overall dimensions shall be 190.5 mm (7–1/2 in.) in length by
The overall dimensions shall be 190.5 mm (7–1/2 in.) in length by
27.7 mm (1–3/32 in.) in diameter. The handle diameter shall be
27.7 mm (1–3/32 in.) in diameter. The handle diameter shall be
24.1 mm (15/16 in.) The weight shall be 250 grams (8.8 oz).
24.1 mm (15/16 in.) The weight shall be 250 grams (8.8 oz).
The microphone shall be capable of being powered by a phantom
The microphone shall be capable of being powered by a phantom
power supply with an output of 11 to 52 Vdc, or by a mixer, audio
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, or by
console or tape recorder capable of supplying 11 to 52 Vdc, or by
an internal 1.5-volt battery.
an internal 1.5-volt battery.
The microphone shall be a Shure Model SM94.
The microphone shall be a Shure Model SM94.
FURNISHED ACCESSORIES
FURNISHED ACCESSORIES
Swivel Adapter .................................................................. A25D
Swivel Adapter .................................................................. A25D
Carrying/Storage Bag ...................................................... 26A13
Carrying/Storage Bag ...................................................... 26A13
OPTIONAL ACCESSORIES
OPTIONAL ACCESSORIES
Phantom Power Supply.................................................... PS1A
Phantom Power Supply.................................................... PS1A
Switch-Selectable Attenuator ........................................ A15AS
Switch-Selectable Attenuator ........................................ A15AS
Isolation Mount ................................................................. A53M
Isolation Mount ................................................................. A53M
Windscreen ..................................................................... A3WS
Windscreen ..................................................................... A3WS
7.6 m (25 ft.) Cable .......................................................... C25J
7.6 m (25 ft.) Cable .......................................................... C25J
REPLACEMENT PARTS
REPLACEMENT PARTS
Screen and Grille ......................................................... RK255G
Screen and Grille ......................................................... RK255G
CLASS A
CLASS A
COMPOUND
COMPOUND
AMPLIFIER
AMPLIFIER
REVERSE VOLTAGE
REVERSE VOLTAGE
FIGURE 4
FIGURE 4
3
3
BALANCED
BALANCED
TRANSFORMER
TRANSFORMER
RFI
RFI
FILTER
FILTER
REGULATOR/
REGULATOR/
PROTECTOR
PROTECTOR
Advertisement
