What Does it Mean to Bridge an Amplifier?

bridged amplifier diagram

For any car audio enthusiast, no sound system is truly complete without a killer subwoofer paired with the best accessories. Of course, to power all these incredible electronics, you need a source. This is where your amplifier comes into play. However, picking out the right amplifier for your sound system is a lot harder than it sounds. For newbies to the scene, ordering a pre-matched set is recommended because pairing all the units can prove to be a daunting task. But hardcore audiophiles who live and breathe music prefer to take a more hands-on approach when dealing with their music. If we’re talking amps, then it’s worth knowing how to perform one of the most important operations; bridging your amplifier. So, what does it mean when an amp is bridged?

Amplifier Bridging

Bridging an amplifier refers to the process of combining two of four channels into one or two channels with half the ohms. The technique has become very popular among many car owners because it allows amplifiers to send out a more powerful mono signal to the subwoofer or speakers. For example, you have a 2-channel amplifier installed in your vehicle with a rating of 75 watts (RMS) for each channel. At 4 ohms, it may be able to push out as much as about 200 watts into a single channel when bridged. This is a highly versatile way of powering a subwoofer. However, bridging is like a fine art that requires precision. But before we show you how to bridge your car amplifier, here’s a small disclaimer you should keep in mind.

Tips to Consider Before Bridging Your Amplifier

Since not all amplifiers can be bridged, the first and most important thing you need to consider is what category yours falls into. This information is typically indicated in the documents and pamphlets that come with the amp. However, if your amplifier lacks the documents, you can just go online to check out the specifications.

Secondly, it is worth noting that bridging cuts the resistance load or ohms in half; this can quickly cause your amplifier to overheat and shutdown. Make sure you give your manual a good look over and see whether your amplifier can actually function at half the ohms it was originally intended to. Other amplifiers are also internally bridged and do not require any further bridging, something to be cautious of.

How to Bridge your Amplifier

If you have a two-channel amplifier in your car’s system, you should be able to see 4 terminals; two positives and two negatives. Channel 1 will be labeled A for positive and B for negative while channel 2 will be labeled C for positive and D for negative. To bridge, begin by connecting the amplifier to the speaker.

From the speaker wires, connect the positive lead to terminal A and the negative speaker lead to terminal D. You can achieve this by using a Phillips screwdriver to unscrew the terminal screws. Next, place the wire between the bottom and top portions of the terminal and put the screws in place. This connection combines all the power from the two separate channels and doubles your power output.

amplifier bridge diagram

If you have a four channel amplifier and want to bridge it with two subwoofers, the procedure is pretty much the same as the previous amp with a few minor differences. First take the necessary precautions to ensure that your amp can be bridged. On a typical 4 channel amplifier, you should see a total of 8 terminals; channels 1 through 4 are labeled as follows. The first channel is marked A for positive and B for negative. Channel two reads C for positive and D for negative. Channel 3 has an E for positive and an F for negative terminals while channel 4 indicates G as the positive terminal and H as the negative terminal.

Connect sub 1 to the first two channels just as you would normally do for a two channel amplifier. This means you will connect the positive wire to terminal A while the negative wire is connected to terminal D. For sub 2, connect the positive lead wire to terminal E while the negative lead should go to terminal H. Now your amp is bridged!

Final Words

That’s basically the gist of bridging your car amplifier to produce a higher power output. And remember, if you can’t perform the bridging process on your own, it’s always advisable to take it to a professional to get the job done right. Alternatively, you can just purchase an amplifier that is already bridged to bypass the process. Lastly always check your amplifiers specifications to ensure that it can be bridged.


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