What is meant by bridged mode?

Question

This is from the power amplifier.

Answer 1

Bridging an amplifier refers to configuring a two channel (stereo) amplifier to drive a single load with more power than the sum of the two original channels combined. For an example, a 100 watt per channel amp may put out 300 watts (one channel) after bridging.   A configuration for creating a larger output voltage swing than that possible with one amplifier by inverting a second amplifier and connecting the load (such as a loudspeaker) between the two outputs.  If a single amplifier is able to produce ±10 V relative to ground (20 Vp-p), then the second amplifier will output the same signal, but inverted. If the load is connected between the positive ("hot") outputs of the two amplifiers (instead of connecting between one output and ground), it can see up to 10 V − (−10 V) = ±20 V (or 40 Vp-p) total, which is twice what each individual amplifier can put out. Driving the load in antiphase makes each amplifier see only half the load's impedance. Because the available voltage swing across the load is doubled for the same power supply voltage, bridged output enables the design of an amplifier producing 4x the power output on the same supply voltage, since power varies as the square of the voltage:

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Answer 2

In bridged mode on an amplifier two things occur:

1 - You lose a channel.  Your amp is now mono (one channel) rather than stereo (two channel).  The amplifier will only amplify one channel (usually designated on the back of the amplifier near the input).

2 - You gain more power.  Typically a doubling or more of power.

The typical application of bridged amps is to buy two amps that can be bridged, set them to bridged mode then use one for each channel to create some serious volume.