How to Bridge a Stereo Amplifier to Mono

By Kevin Krause

A bridged amplifier uses the output from the two stereo channels to drive a single mono speaker load. It is often done to achieve a higher output from the amplifier by combining the available power of both channels. While it is not necessary when the amplifier is properly connected to stereo speaker cabinets, a bridged amp may be desirable if the system is to be run in mono. This will allow you to use the full power of the amplifier when it would otherwise be halved. Bridging a stereo amp is an easy procedure, but should only be undertaken on an amp that is designed to be bridged.

Things You'll Need

  • Bridgeable amplifier
  • Speaker cable

Step 1

Power off the amplifier before connecting to a speaker cabinet, and ensure that the speaker cabinet to be used is capable of handling the output load. The output impedance will double when the amp is bridged (for example, if the amp runs at 2 ohms stereo output, the mono bridged output will be 4 ohms).

Step 2

Connect a speaker wire or cable to the "+" output of the first stereo channel. Connect the other end of the speaker cable or wire to the "+" terminal of your speaker cabinet.

Step 3

Connect a speaker wire or cable to the "-" output of the second stereo channel. Connect the other end of the cable to the "-" terminal of the speaker cabinet. The amplifier is successfully bridged to mono.

Step 4

Power on the amplifier and play a signal through to the speaker to make sure everything is in proper working order. If there is no signal, power off the amplifier immediately and double check that all wiring is correct.

Tips & Warnings

  • Bridging an amplifier does not necessarily create a louder output than a stereo amplifier. When connected to proper stereo speakers, the output will be equal as when it is bridged in mono. Bridging is most useful when stereo output is not available but increased power is desired.
  • The owner's manual will contain more information about how to bridge your specific amp. Always be sure the amp is designed to be bridged. This will typically be indicated by a diagram near the outputs with a line drawn between the outputs to be used for bridging.
  • Do not attempt to bridge an amp that is not designed for such use. This will cause damage to your amplifier and may destroy your speakers.