Yorkville Sound AP312 Power Amplifier General, Speaker Connections, Power Amplifier Protection

3.Now connect one 8 ohm subwoofer to the AMP 1 SPEAKER OUTPUT jack and one 8 ohm full-range cabinet to the AMP2 SPEAKER OUTPUT jack.

4. The complete system is now functional, not including monitors. How-ever, if you need to vary the compara- tive volume levels of the subwoofer/s relative to

the full-range cabinets, another setup will be

required with an exter- nal power amp for the subwoofers or employing powered subwoofers.

In that system, AMP 1 would be for full-range speakers and AMP 2 would be for monitors. In other words, this is a standard setup but with the MAIN (L) LINE OUTPUT going to the input of the processor/crossover and then to an external amp driving the subwoofer/s, or simply direct to the input of a powered subwoof- er (ours have crossovers built in).

Power Amplifier - General

The AP312 has a built-in 320 watt stereo power amplifier. Each channel has an input sensitivity of +4dBv (1.4 volts RMS) for full-power output and each can deliver over 160 watts into a 8 ohm speaker load. These amplifiers incorporate computer designed internal heatsinks and a variable-speed fan which automatically provides quiet opera- tion consistent with cooling requirements. Cool air is drawn into the front of the mixer, and heated air is expelled along the bottom of the back. Even at maximum power, this arrangement results in quiet, dependable performance.

PLEASE NOTE: THE AIR VENTS AT THE FRONT AND BOTTOM REAR OF THE MIXER ARE ESSENTIAL FOR PROPER OPERATION. BLOCKING THE FREE FLOW OF AIR THROUGH THE MIXER WILL RESULT IN SYSTEM SHUT-DOWN DUE TO OVERHEATING. REPEATED OVERHEATING MAY EVENTUALLY CAUSE DAMAGE. PLEASE KEEP THE VENTS FREE OF OBSTRUCTIONS.

Speaker Connections

The two 1/4-inch jacks are in parallel with each amp-channel output stage. This allows the use of speaker cables equipped with either type of connector. For full-power applica- tions we recommend 18-gauge cables or heavier - possibly 16-guage, or even 12-guage

Connect one or two 8 ohm speakers to each channel.

Note: The amplifier puts out maximum power into 8 ohms per channe

Power Amplifier Protection

The AP312’s power amplifier is protected from damage due to open, shorted or exces- sively low speaker loads. It will continue to run into a low (less than 4 ohms) overall speaker impedance, or even a total short circuit, however the output power will be automatically reduced to maintain an optimum safe operating temperature. In a worst- case situation, the thermal breaker on the transformers primary windings will shut the AP312 down until it cools sufficiently.

User tip: Cooling will require a few minutes. Take this time to check the number, and impedances of connected speakers (are there significantly more than two 8 Ohm speakers per channel?). Also check inside the speaker cable jacks; there may be stray bits of wire that could be causing short circuits. Also, connection tabs may be too close to each other. Remove the short and/or reduce the number of connected speak- ers.

AC Power Circuit-Breaker

Located on the back panel near the SPEAKER connectors, this circuit breaker’s main function is to shut the AP312 down completely in case of an AC power overload. If, for example, the unit were accidentally connected to a high-voltage power outlet, this

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