Bridging subwoofers is an excellent choice for connecting multiple subwoofers to a mono (or single channel) amplifier. Bridging subwoofers can also be used with a multichannel amplifier to increase the power delivered to each speaker. Knowing how to bridge subwoofers correctly is important before attempting to install because improper installation can result in serious equipment damage.
Step 1. Determine if the subwoofers can be safely bridged to the amplifier
The safety in question here is a matter of impedance or resistance. Start with the impedance for the 2 subwoofers you want to bridge. For example, if each of your subwoofers is rated at 4 ohms, they will only provide a 2 ohm impedance when bridged. If your amplifier is not rated for 2 ohms, then it is not safe to use this system; your amplifier will try to deliver much more power than it is capable of and overheat quickly.
Step 2. Install the required wire
To bridge the 2 SVC (single voice coil) subwoofer using a single-channel amplifier, you will need 2 positive (red) stereo wires and 2 negative (black) stereo wires.
Step 3. Wire the amplifier to the first subwoofer
Wire the first speaker as usual, starting by connecting the red wire from the positive terminal on the amplifier to the positive terminal on the speaker. Then connect the black wire from the negative terminal on the amplifier to the negative terminal on the speaker.
Step 4. Wire the second subwoofer to the first subwoofer
To bridge the second speaker to the first, run the red wire between the positive terminals on both speakers, and the black wire between the negative terminals. After that, the first subwoofer must share both of its 2-wire terminals, since it is connected to both the amplifier and the second speaker. The subwoofers are now bridged.
Method 1 of 1: Connecting 2 DVC Subwoofers Using a Mono Amplifier
Step 1. Install the required wire
DVC (Dual Voice Coil) subwoofers have two pairs of terminals each, and thus wiring is a little more difficult than setting up an SVC. You will need 6 pieces of stereo wire: 2 positive, 2 negative, and 2 that will simply be used for bridging.
Step 2. Wire the amplifier to the first subwoofer
Start by running the red wire from the positive terminal of the amplifier to the first positive terminal on the speaker. Run the black wire from the negative terminal of the amplifier to the second negative terminal on the speaker.
Step 3. Wire the second subwoofer to the first subwoofer
Run the red wire between the first positive terminals on each speaker. Run the black wire between the second negative terminal on each speaker. The first subwoofer should now share its 2 terminals with both the amplifier and the second subwoofer.
Step 4. Connect each subwoofer with a "bridge"
At this point, each subwoofer must have 2 unused terminals: the first negative terminal and the second positive terminal. On each speaker, use a short length of stereo wire to connect these terminals. The subwoofers are now bridged.