Crown SMX-6, MPX-6, AMB-5 installation manual Stack Inputs, Paralleling Inputs

IQ Mixer / Multiplexer Hardware Installation

3.3.4 Stack Inputs

The stack in jacks (Figure 3.15) enable the audio inputs to be increased by stacking 2, 3, or more mixer/multiplexers to create a 12x2, 18x2 or wider mixer. Use 2-conductor shielded cable to route the signal from the main output of one unit to the stack input (RCA phono jack) of the second unit. This is shown in Figure 3.19. The stack input routes the signal directly to the output of the second unit. Use the outputs of the last unit in the stack for connec- tion to amplifiers or other external audio equipment.

Note: The level of each signal on the stacked output bus is controlled by the unit having the signal as an input.

Stacking mixer/multiplexers can create an almost unlimited number of inputs. However, there will still only be two main and two auxiliary bus outputs for connection to other equipment. See Section 3.3.5 to find out how to increase the number of outputs.

The correct way to wire stacked units is shown below:

12 INPUTS

MAIN STACK

OUT IN

SMX-6	SMX-6	2
		OUTPUTS

STACKED

OUTPUTS

Fig. 3.18 A 12x2 Mixer Using 2 Mixer/Multiplexers

First	AUDIO	STACK	AUDIO	STACK
	OUT	IN	OUT	IN
Unit
	2 MAIN		1 MAIN
		BUS		BUS
	+ –	+ –	+ –	+	–
		3-pin output connector
		(–) No connection
		2-conductor shielded cable
		Connect ground (			) from
		output to phone plug shield
		Phone (RCA) plug
Second	AUDIO	STACK	AUDIO	STACK
	OUT	IN	OUT	IN
Unit
	2 MAIN		1 MAIN
		BUS		BUS

+ – + – + – + –

Fig. 3.19 Stacking the Outputs of Multiple Units

3.3.5 Paralleling Inputs

When using more than one unit, the inputs may be wired in parallel to increase the number of outputs that a source can drive. This is shown in Figures 3.20-21. For example, the audio signal in Figure 21 which feeds Input 1 is available to the outputs of both units, creating a 6x4 mixer.

Important: If the source is a microphone which re- quires phantom power (P) select it only at the first input. Switch all other parallel inputs to mic (M).

Note: When mixer inputs are paralleled, the total input impedance will drop by 1¦N where N is the number of inputs to be connected. Depending on the signal source, this may place a limit on the number of possible outputs.

6 INPUTS

SMX-6

PARALLELED

INPUTS

MPX-6

8 OUTPUTS

MPX-6

MPX-6

Fig. 3.20 A 6x8 Mixer Using 4 Mixer/Multiplexers

To signal source

First	AUDIO		ADD 25	AUDIO		ADD 25
Unit	IN	0	5 FOR MIC	IN	0	5 FOR MIC
		-5	10		-5	10
	2	-10	15	1	-10	15
		-12	21		-12	21
				+	–
			M L P			M L P

+ –

Do NOT tie ground terminals of parallel inputs together

2-conductor shielded cable

Connect shield to ground terminal of input ONLY

Second	AUDIO		ADD 25	AUDIO		ADD 25
Unit	IN	0	5 FOR MIC	IN	0	5 FOR MIC
		-5	10		-5	10
	2	-10	15	1	-10	15
		-12	21		-12	21
						No
			M L P			M L P phantom
	+	–		+	–	power

Fig. 3.21 Paralleling the Inputs of Multiple Units

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