How Do I Bridge my Amplifier ?

Bridge mode is commonly used to get more output power from amplifiers by combining two single channel outputs into one output. This can only be done safely if you know the minimum load (Ohms) permissible when bridged. This is more common when driving sub-woofers that have dual voice coils, or when you have multiple sub-woofers. First check the installation manual or look at the speaker terminal block on the amplifier, as they normally have a diagram showing the bridged connections.

Below is an example of a 4 channel amp speaker connection terminal block. As shown, bridging is achieved by connecting the positive terminal from the left channel and the negative terminal of the right channel to the corresponding terminals on the sub-woofer coil or coils depending on configuration. There are a number of different configurations depending on the load applied to the amplifier - see sub-woofer coil configuration. It all depends on whether you have a 4 Ohm, 2 Ohm or 1 Ohm stable amplifier (mono). An example of the different power ratings for a four channel amplifier is below.

100 Watts RMS x 4 @ 4 Ohms
200 Watts RMS x 2 Bridged @ 2 Ohms

These are examples only to give you an idea how this works. This also supplies for 2 channel amplifiers and depends on whether they are Class-AB or Class-D amplifiers, as the 1 Ohm rating applies to Class-D amplifiers in general.