You can cut in half the number of channels used by the amp while doubling the power feed to each speakers with bridging method. This bridging method enables a powerful mono signal to be sent to a subwoofer, this method are commonly used in car audio systems.
To properly bridge an amp is very easy and simple, but when not properly done it can seriously damage the equipment. Here’s how:
First you have to know for sure that the amp can be bridged, you can check this out on the amp’s manual that came with it. But if you are using second hand amp without a manual, you can check the amp’s specifications on the website of the amp’s manufacturer.
We’ll use an example of 2 channel amp bridging on this article. But understand also that a four channel amp can be bridged to two channels.
In two channel amp there are four terminals, a positive and a negative terminal for channel 1 and a positive and negative terminal for channel 2. To make it easier we label each terminal as follows, A = channel 1, positive. B = channel 1, negative. C = channel 2, positive. D = channel 2, negative.
If you are using the amp to power one speaker you can connect the red/ribbed speaker wire to terminal A. Now connect the black/non-ribbed speaker wire to terminal D.
Be sure the amp you’re going to bridge is not already bridged on the inside. Some amp are made of two smaller amp internally bridged. Check by turning the amp on and measure the voltage between the negative speaker output and the car’s ground. If it indicate any non-zero value, the amp is already bridged and if you continue to bridge the amp, this may cause a bad noise output. If you are uncertain with the amp’s condition, you can ask a professional car audio shop before you try to bridge them.
