operation modes 4
stereo
For stereo (dual channel) operation, turn the amplifier off and set the mode select switch to the stereo position. In this mode, both channels operate independently of each other, with their input attenuators controlling their respective levels. Thus, a signal at channel A’s input produces an amplified signal at channel A’s output, while a signal at channel B’s input produces an amplified signal at channel B’s output.
parallel
For parallel (dual-channel/single input) operation, turn the amplifier off and set the mode switch in the parallel position; both amplifier channels are then driven by the signal at channel A’s input. No jumper wires are needed. Output connections are the same as in the stereo mode. Channel A’s and channel B’s input connectors are strapped together to allow patching to another amplifier. Both input attenuators remain active, allowing you to set different levels for each channel. Power and other general performance specifications are the same as in the stereo mode.
bridged mono
Both amplifier channels can be bridged together to make a very powerful single-channel monaural amplifier. Use extreme caution when operating in the bridged mode; potentially lethal voltage may be present at the output terminals. To bridge the amplifier, turn the amplifier off and slide the rear panel amplifier mode select switch to the bridge position. Apply the signal to channelA’s input and connect the speakers across the hot outputs which are either the “+” binding posts of channels A and B. Alternately connect across pins “1+POS” and “2+NEG” of the channel A Speakon® connector. As with parallel operation, both input connectors are strapped together to drive the input of another amplifier.
Unlike the stereo and parallel modes, in which one side of each output is at ground, in the bridged mode both sides are hot. Channel A’s side is the same polarity as the input.The minimum nominal load impedance in the bridged mode is 4 ohms which is equivalent to driving both channels at 2 ohms. Driving bridged loads of less than 4 ohms will activate the ACL circuitry resulting in a loss of power, and may also cause a thermal overload.
When operating in the bridged mode, both attenuators must be in the same position so the speaker load will be equally shared between the channels.