|MadSci Network: Engineering|
Hi! That depends on how the amplifiers are connected internally. Most power amplifiers have the red plus terminal "hot" (i.e. carrying the amplified signal) and the black minus terminal connected to ground. In that case, the amplifiers can be bridged by supplying one channel's input with an inverted version of the input signal that goes to the other channel. The load is then connected across the red terminals only. Keep in mind that a bridged amplifier effectively puts out twice the output voltage compared to normal use. To make sure that output current does not double also, the rated minimum load impedance must be doubled. If the amplifier states 4 ohms minimum load, you shouldn't connect less than 8 ohms to it when it is bridged. Otherwise it would be delivering more than twice its rated output power which is no longer safe. Some amplifiers are internally bridged by default. This means they already consist of 2 amplifiers each feeding an output terminal and no terminal is grounded. In that case further bridging is not possible. It can be checked simply by turning the amplifier off and measuring (using an ohm meter) if the black terminals are connected internally [and to ground]. The phase invertor can be made using a standard -1 gain op-amp circuit. Regards and good luck, Bruno Putzeys
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