Mackie SP2400 Instruction Manual - All - Page 12

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. 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 rolloff 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). High-Frequency Rolloff Maximum Feet of Cable vs. High-Frequency Roll-Off 20K 16K 12.5k 10K 8K 6.3K 5K 4K 3.15K 1.6K 0 -1 dB point -3 dB point Expansion Bus Output Impedance = 220Ω Expansion Bus Input Impedance = 200KΩ 20pf/ft 30pf/ft Feet of Cable (24AWG) Distance Chart for SP2400 Expansion Bus Cable 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 For local interconnection of the Expansion Bus, the use of standard computer cable with an overall shield is acceptable, such as Belkin Pro Series 25Conductor 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. EXPANSION I/O -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 (-) 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 (+) 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