SHURE 550L
Owner's Manual

Model 550L User Guide
TRANSMIT

RED BLACK BLACK WHITE WHITE GREEN SHIELD

GENERAL The Shure 550L is an omnidirectional dynamic base station microphone with a frequency response specially tailored for voice intelligibility. It is equally useful for radio communications, paging and dispatching systems, and its low-impedance connection makes it adaptable to most PA amplifiers. The low-impedance design also makes it useful for long runs of cable, or under severe hum disturbance conditions. The microphone is not affected by heat or humidity. Its exclusive ARMO-DUR® case 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

The 550L may be wired for balanced or unbalanced operation. For unbalanced operation, the green cable wire is connected to the audio input, the white cable wire is connected to the audio ground, and the shield is connected to the chassis ground. See Table 1. For balanced operation, the green cable wire is connected to the audio input positive (+), the white wire is connected to the audio negative (-), and the shield is connected to the chassis ground. See Table 1. Table 1. Cable-to-Connector Wiring
WIRE COLOR INPUT TYPE GREEN UNBALANCED WHITE SHIELD GREEN BALANCED WHITE SHIELD AUDIO AUDIO GROUND CHASSIS GROUND AUDIO + AUDIO CHASSIS GROUND PIN 2 PIN 3 PIN 1 PIN 2 PIN 3 PIN 1 TIP SLEEVE SLEEVE TIP RING SLEEVE FUNCTION XLR CONNECTOR 1/4 IN. PHONE PLUG

INTERNAL CONNECTIONS FIGURE 1

� Low-impedance operation � 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 microphone case resists corrosion � Reliability 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 transmission. WIRING Figure 1 shows the internal wiring of the 550L microphone.

NOTE: The red and black wires are not part of the audio circuit. These wires provide a contact closure when the microphone switch is depressed. This closure may be used to control an external relay or transmit/receive circuit.

IMPEDANCE MATCHING Low-impedance operation is extremely useful where long cable lengths are required, or under conditions of severe hum disturbance. The permissible cable length is practically unlimited, since neither response nor level is appreciably affected. Shure A95 Series Line Matching Transformers are available for use in those cases where a low-impedance microphone is to be used with an amplifier with a high-impedance input. These transformers provide a proper impedance match between a 19- to 300-ohm microphone and a high-impedance input, and are available with various input and output connectors.

©2005, Shure Incorporated 27C8090 (Rev. 4)

Printed in U.S.A.