Mackie SP2400 Connecting the Expansion Bus, Connecting the Remote Bus, Ground Input 2 Right +

the amplifier output is configured for 8-ohm operation, connect the speaker output directly to an 8-ohm load. The amplifier will deliver up to 250 watts to each speaker. If the amplifier is configured for either 70V or 100V operation, connect the speaker output directly to the distributed system. No output transformer is required. Make sure that the taps on the speakers add up to 200 watts or less per amplifier for 70V or 100V systems.

–15VDC (w/J2 INSTALLED) N/C PAGING MIC (+)

INPUT 4 RIGHT (+)

INPUT 4 LEFT (+)

INPUT 3 RIGHT (–)

INPUT 3 LEFT (–)

GROUND INPUT 2 RIGHT (+)

INPUT 2 LEFT (+)

INPUT 1 RIGHT (–)

INPUT 1 LEFT (–)

EXPANSION I/O

25 13

14 1

+15VDC (w/J3 INSTALLED) PAGING MIC CONTROL PAGING MIC (–)

INPUT 4 RIGHT (–)

INPUT 4 LEFT (–)

GROUND

INPUT 3 RIGHT (+)

INPUT 3 LEFT (+)

INPUT 2 RIGHT (–)

INPUT 2 LEFT (–)

GROUND

INPUT 1 RIGHT (+)

INPUT 1 LEFT (+)

Connecting the Expansion Bus

These are 25-pin D-Sub connectors (DB25F). The two connectors are wired in parallel, so it doesn’t matter which one you use as an input or output. The signals on the EXPANSION IN/OUT are balanced so they can be transmitted down long lines. The limiting factor is the capacitance of the cable, which causes the higher frequencies to roll- off as the capacitance increases (see chart below). The chart indicates the lengths of cable at which the high-frequencies are 1 dB down and 3 dB, using cable rated at 20pf/ft and 30pf/ft.

Use shielded twisted pairs for the EXPANSION cable to ensure the best rejection of external noise (EMI and RFI).

	Maximum Feet of Cable vs. High-Frequency Roll-Off
	20K
Rolloff	16K
	12.5k
Frequency-High	10K
	3.15K
	8K
	6.3K
	5K	–3 dB point
	–1 dB point
	4K

1.6K									Expansion Bus Output Impedance = 220Ω
0									Expansion Bus Input Impedance = 200KΩ
0	100	200	300	400	500	600	700	800	900	1000	1100	1200	1300	1400	1500	1600	1700	1800	1900	2000
							Feet of Cable (24AWG)
			20pf/ft
			30pf/ft

Distance Chart for SP2400 Expansion Bus Cable

For local interconnection of the Expansion Bus, the use of standard computer cable with an overall shield is acceptable, such as Belkin Pro Series 25- Conductor Straight-Through Cable Assembly (Part Number F3D111-06) or equivalent. Ensure that the cable is wired straight-through and terminated to DB25M connectors on each end.

Note: The use of ribbon cable is permissible for these connections, only where the total length of each cable is 12" (30cm) or less.

Signal	Pin No.
Input 1 Left (+)	Pin 1
Input 1 Left (–)	Pin 14
Input 1 Right (+)	Pin 2
Input 1 Right (–)	Pin 15
Ground	Pin 3
Input 2 Left (+)	Pin 16
Input 2 Left (–)	Pin 4
Input 2 Right (+)	Pin 17
Input 2 Right (–)	Pin 5
Ground	Pin 18
Input 3 Left (+)	Pin 6
Input 3 Left (–)	Pin 19
Input 3 Right (+)	Pin 7
Input 3 Right (–)	Pin 20
Ground	Pin 8
Input 4 Left (+)	Pin 21
Input 4 Left (–)	Pin 9
Input 4 Right (+)	Pin 22
Input 4 Right (–)	Pin 10
Paging Mic (+)	Pin 23
Paging Mic (–)	Pin 11
N/C	Pin 24
Paging Mic Control	Pin 12
–15VDC (w/J2 Installed)	Pin 25
+15VDC (w/J3 Installed)	Pin 13

Note: There is a 0.5 amp limit on the ±15VDC supply.

Expansion Bus Connection Chart

Connecting the REMOTE Bus

This is a 3-pin Phoenix-type connector specifically for connecting the optional remote control. Use a high-quality three-conductor shielded cable to make this connection, such as Belden 8451, 9451, or equivalent. The lower the nominal capacitance of the wire, the more distance you can have between the remote control and the SP2400 before suffering transmission losses.

Strip the wire back about 1/4 inch, insert the wire as far as it will go into the appropriate hole in the supplied Phoenix-type connector, and tighten down the screw with a small slot-head screwdriver. It is recommended that you use 18 to 24 gauge wire for the remote control connections, depending on the distance between the SP2400 and the remote control.

SP2400 – 12