How to Bridge Two 4-Channel Amplifiers to Two Subwoofers

Bridge 4-channel amplifiers to maximize bass.

Four-channel amplifiers offer versatility in the car audio realm. Better units offer the ability to safely bridge into two channels, allowing a larger amount of power to flow to speakers such as subwoofers, where more current is required. Since all bridgeable 4-channel amplifiers are essentially two 2-channel amps strapped together internally, bridging these units is not only safe, but encouraged if you need this extra power.

Things You'll Need

• Speaker wire
• Wire strippers
• Screwdriver (Philips, flat-head, Allen)

Instructions

1. Locate the four speaker wire terminals on each amplifier. Loosen each screw with the appropriate screwdriver, enough to allow insertion of the speaker wire.

2. Strip 1 inch of insulation from both ends of the speaker wire. Insert the designated positive speaker conductor into the left front channel's positive terminal. Secure with the set screw and appropriate screwdriver. Repeat for the right rear channel's negative terminal. Perform this process for both amplifiers.

3. Loosen the subwoofers' binding posts, exposing the center hole. Insert the bare wire from the amplifier's positive terminal into the designated positive binding post on the subwoofer. Repeat for the negative terminal. Perform this process for both subwoofers.

4. Flip the "4CH/2CH" switch on each amplifier to 2-channel operation.

Tips & Warnings

• Always perform all amplifier connections with the vehicle turned off.

References

• Basic Car Audio Electronics: Bridgeable Amplifiers
• Crutchfield: Subwoofer Wiring Diagrams

Resources

• DIY Mobile Audio: 4-Channel Bridged to a 2-Channel