Shure 550L User manual

Model 550L User Guide
Shure Brothers Incorporated
222 Hartrey Avenue
Evanston IL 60202-3696 U.S.A.
27A8090 (RB)
E1998, Shure Brothers Incorporated Printed in U.S.A.
MODEL 550L
OMNIDIRECTIONAL DYNAMIC
BASE STATION MICROPHONE
The Shure 550L is a dynamic base station micro-
phone with a frequency response specially tailored for
voice intelligibility. It is equally useful for radio commu-
nications, paging and dispatching systems, and its
low-impedanceconnectionmakesitadaptabletomost
PA amplifiers. The low-impedance design also makes
itusefulforlongruns,orunderseverehumdisturbance
conditions.
Themicrophoneisnotaffectedbyheatorhumidity.
Its exclusive ARMO-DURRcase is immune to oil,
grease, fumes, salt spray, sun, rust, and corrosion
—and is outstanding in its ability to resist mechanical
shocks and vibration. The “Million-Cycle” leaf-type
switch is designed to withstand rigorous operating
conditions and constant use.
Features
• Low-impedance operation for long cable runs or
severe hum disturbance
• Crisp, natural, high-intelligibility voice response
• Fingertip control bar actuates microphone circuit
and external relay or control circuit
• Long-life switch meets rigorous requirements of
communications and paging systems
• Sturdy, high-impact ARMO-DUR base and micro-
phone case—impervious to corrosion
• Reliability plus—under all operating conditions
• Neoprene feet prevent microphone slipping
PRESS-TO-TALK SWITCH OPERATION
The fingertip control bar is a non-locking switch;
simply depress the control bar and release after trans-
mission.
CONNECTIONS
Figure 1 shows the internal wiring of the 550L
microphone. The 550L is designed for balanced-line,
low-impedance operation. The WHITE and GREEN
cableleads arethe twoconductors forthe microphone
circuit; the shield is connected to the amplifier or chas-
sis ground. The RED and BLACK leads control an ex-
ternal relay or switching circuit.
RED
ORANGE
RED
BLACK
WHITE
GREEN
SHIELD
TRANSMIT
INTERNAL CONNECTIONS
FIGURE 1
Low-impedance operation is extremely useful
wherelongcable lengthsarerequired, or undercondi-
tions of severe hum disturbance. The permissible
cable length is practically unlimited, since neither re-
sponse nor level is appreciably affected. Shure A95
Series Line Matching Transformers are available for
use in those cases where a low-impedance micro-
phone is to be used with an amplifier with a high-
impedanceinput.Thesetransformersprovideaproper
impedance match between a 19- to 300-ohm micro-
phone and a high-impedance input, and are available
with various input and output connectors.

SPECIFICATIONS
Type
Dynamic
Frequency Response
150 to 6,000 Hz (see Figure 2)
TYPICAL FREQUENCY RESPONSE
FIGURE 2
Polar Pattern
Omnidirectional
Impedance (at 1,000 Hz)
Microphone rating impedance is 150 ohms (220
ohms actual) for connection to microphone in-
puts rated at 75 to 300 ohms
Output Level (at 1,000 Hz)
Open Circuit Voltage* –74.0 dB (0.2mV)
. . . . . . . .
Power Level** –53.5 dB. . . . . . . . . . . . . . . . . . . . . . . .
*0 dB = 1 volt per microbar
**0 dB = 1 milliwatt per 10 microbars
Switch
Press-to-Talk Switch actuates microphone circuit
and external relay or control circuit. Microphone
circuit normally open.
Cable
2.1m (7 ft) four-conductor, two conductor
shielded, non-detachable
Case
Brown ARMO-DURRwith dull chrome-plated
steel screen
Dimensions
See Figure 3
OVERALL DIMENSIONS
FIGURE 3
Net Weight
836 grams (1 lb 13-1/2 oz)
Shipping Weight
1.12 kilograms (2 lb 7-1/2 oz)
REPLACEMENT PARTS
Cartridge R50
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cable C32C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Switch RK321S. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
For additional service or parts information, please
contact Shure’s Service Department at 1–800–
516–2525. Outside the United States, please contact
your authorized Shure Service Center.