Shure SR105 service manual Output Connections

@ UNBALANCED PARALLELED

MIXER-

PREAMPLIFIERPOWER

AMPLIFIER

0

I	I I	I I
	\/	\ A
0		UNBALANCED PARALLELED
		HIGH-IMPEDANCE INPUTS
		A-
		- +	BALANCED
			BRIDGING
			I
			INPUT

MIXER-SR105

PREAMPLIFIERPOWER

AMPLIFIER

@6-TT-5SLEEVE

570,114 W TIP

FIGURE 5. INPUT CONNECTIONS

-TO POWER AMPLIFIER OR HIGH-IMPEDANCE

TAPE RECORDER INPUT

TO POWER AMPLIFIER OR OTHER AUXILIARY

EQUIPMENT

OUTPUT CONNECTIONS

Four standard 1/4" phone jacks (8) and one two-terminal barrier strip (9) on the rear panel of the Amplifier provide direct-coupled speaker output connections (see Figure 2, Page 2). All connectors are wired in parallel and pro- vide for simultaneous connection of a number of speaker systems. A three-terminal barrier strip ( l l ) , labeled 70V OUTPUT (SR105A Amplifier only), provides for connec- tion to the 70-volt output of the Amplifier (see Figure 2, Page 2). This output is present only when the 70V-OFF Switch (10) is set to the 70V position.

The Amplifier utilizes direct coupling between the output stage and the direct-coupled speaker output load. The full-rated 200-watt output of the Amplifier is obtained when the speaker load connected to the DIRECT OUTPUT ter- minals (8,9) is four ohms. The output voltage under these conditions is 28.3 volts. Speaker loads of less than four

ohms should not be used with this Amplifier. If less than four ohms is inadvertently used, no damage to the speak- ers or Amplifier will occur, but a reduction in power output and an increase in distortion will be experienced. Thermal shutoff of the Amplifier may also result.

It should be noted that various speaker loads will affect the output power of the Amplifier. See Figure 6, Page 7, to determine Amplifier output power for a given speaker load. Refer to the section entitled, Amplifier-to-Speaker Matching (Page 8) for assistance in calculating speaker load.

In the event that an SRlO5A Amplifier is operated in an application where the 70-volt output is not used, the 70V- OFF Switch (10) should be turned off. This disconnects the 70-volt transformer which would otherwise be operating without a load. If the transformer is allowed to operate in a no-load condition, it may activate the output transistor pro-