The AP812/818’s power amplifier also features speaker protection in case of DC-offset. This is a very unlikely occurrence given the amp’s inherently stable design, but should it happen, the output power is instantly shorted to ground and the speak- ers are saved. The AC mains breaker on the back panel will blow in response to this condition (among others). If your breaker blows more than once in a short space of time and the problem does not appear to be AC overload (see below), switch the power off and take your AP812/818 to a qualified technician.
AC Power Circuit-Breaker
Located on the back panel near the SPEAKER connectors, this circuit-breaker’s main function is to shut the AP812/818 down completely in case of an AC power overload. If, for example, the unit were accidentally connected to a high-voltage power outlet, this breaker would open as soon as the AP812/818’s POWER switch was flipped on. If this breaker opens more than once in a short space of time, try plugging the AP812/818 into another power outlet. Also, see above regarding DC-offsetspeaker protection.
Rack Mounting (applies to AP812 only)
To rack-mount the AP812 you will need to purchase a pair of the accessory model RK812 rack ears, then simply remove the three screws holding each of the AP812's two end mold- ings in place and use the screws to mount the rack ears to the sides of the mixer.
General Operating Instructions
1.Connect the AC power cord to a 120 Volt AC grounded power outlet (220 to 240
Volts in export units).
2.Switch on the POWER and turn the MAIN and MONITOR MASTER con- trols to OFF for now.
3.Connect low-impedance microphones to the 3-pin XLR type MIC inputs.
4.Connect high-impedancemics or mono line-level signal sources - i.e. amplifier line outputs, the output of a mono-mixer, an electric instrument, etc. to the 1/4- inch BAL LINE IN jacks. Do not connect more than one thing to any of these channels, that includes stereo outputs (if you try to connect a stereo source to a mono channel using a Y adapter, you may get distortion).
5.Connect stereo sources - tape deck, CD-player, stereo keyboard, instrument, etc. - to channels 9/10 and 11/12 (15/16,17/18), either via the RCA (phono) type inputs or the 1/4-inch BAL LINE IN connectors. Once again, connect only one signal source per channel and use shielded patch cords for all pre-ampconnections.
Stereo sources may be connected to channels 1 through 8 if you use two of them, one panned left, the other right.
Note A: The following setup applies to the system with the EQ/AMP ASSIGN button down in the MAIN/MON position. This is with a mono main mix going to AMP 1 and the monitor mix going to AMP 2 so that the whole system is being powered by the AP812/818.
6.Using heavy-gaugespeaker cables (see under SPEAKER CONNECTIONS) connect one or two 8 ohm main PA speakers to the AMP 1 SPEAKER outputs on the back panel. Similarly, connect one or two 8 ohm monitors, or one 4 ohm monitor to the AMP 2 SPEAKER outputs.
