Model 450 Series II User Guide
WIRING CONNECTIONS
Refer to Figure 1 and Table 1 below. For unbalanced operation, the GREEN wire is connected to the audio input, the WHITE wire is connected to the audio ground, and the SHIELD is connected to chassis ground. In some cases, audio ground and chassis ground will be the same. For balanced operation, the GREEN wire is connected to the positive audio input, the WHITE wire is connected to the negative audio input, and the SHIELD is connected to chassis ground.
IMPEDANCE SWITCH GREEN YELLOW PRESS-TO-TALK SWITCH
LO
HI BLACK
12
3 BLACK RED GREEN WHITE SHIELD
GREEN ORANGE RED
SHURE MODEL 450 SERIES II PAGING AND DISPATCHING MICROPHONE
The Shure Model 450 Series II is a high output dynamic microphone designed for paging and dispatching applications. This extremely rugged microphone features an omnidirectional pickup pattern and a frequency response tailored for optimum speech intelligibility. It also includes an impedance selection switch and a locking press-to-talk switch. The press-to-talk switch can be converted to a monitor/transmit switch with the Shure RK199S Split-Bar Conversion Kit.
WIRING DIAGRAM
WHITE
FIGURE 1
Table 1. Typical Cable-to-Connector Wiring
INPUT TYPE WIRE COLOR GREEN UNBALANCED WHITE SHIELD GREEN BALANCED WHITE SHIELD FUNCTION AUDIO AUDIO GROUND CHASSIS GROUND AUDIO + AUDIO � CHASSIS GROUND XLR CONNECTOR PIN 2 PIN 3 PIN 1 PIN 2 PIN 3 PIN 1 1/4 IN. PHONE JACK TIP SLEEVE SLEEVE TIP RING SLEEVE
Features
� � � � � Dual impedance Locking press-to-talk switch Rugged ARMO-DURR base and case Adjustable height Optional monitor/transmit switch conversion kit
PRESS-TO-TALK SWITCH OPERATION
To operate the control bar as a press�to�talk switch, simply hold it down and begin speaking. When you are finished speaking, release the control bar. To lock the control bar in the �on� position, press it down and pull it forward. To unlock the control bar, push it back and release it.
NOTE: The RED and BLACK leads are not part of the audio circuit. These wires provide a contact closure when the pressto-talk switch is depressed. This closure may be used to control an external relay or a transmit/receive circuit.
CHANGING PTT CIRCUIT TO NORMALLY OPEN
IMPEDANCE SELECTION
To select high or low impedance, move the impedance selection switch, located under the microphone base, to either the HIGH or LO position. The switch is factory pre�set to LO. Shure recommends the low impedance setting if long lengths of cable are used, or if severe hum is encountered. Use Shure A95 Line Matching Transformers to match a low impedance (300 �) microphone line to a high impedance amplifier input.
Using microphones in parallel requires a normally open microphone circuit. To modify the press�to�talk switch so that it provides a normally open circuit, proceed as follows: 1. Remove the screws, washers, and bottom plate from the microphone. 2. Unsolder the black, red, and white leads from the terminal of the press�to�talk switch (see Figure 1). Make sure these leads are still soldered together. If necessary, resolder them and insulate the connection. 3. Replace the bottom plate and secure it with the screws and washers removed in Step 1.
