How to Connect an Amp to a Passive Subwoofer How to Connect an Amp to a Passive Subwoofer

What You'll Need
Passive subwoofer
Amplifier
One or two RCA cables
Speakers
Speaker wires
Power supply

The term passive subwoofer correctly implies that there are no internal amplifiers and therefore external ones would need to be connected. Subwoofers are used primarily for low-frequency sounds and improving the bass quality of your speakers. The size of your room would determine the subwoofer’s size—the bigger the room the bigger the subwoofer. The power ratings and the ohm load are few of the things that you would need to consider for choosing an appropriate amplifier for your subwoofer.

Step 1- Connecting the RCA Cables

The RCA (Radio Corporation of America) cables will be used to connect the sub to the amplifier. The output from the subwoofer can either be monaural or stereo. You can find these on the head unit of your subwoofer (backside). In the case of the monaural output you will need only one RCA cable for the output. For the stereo output you will need two cables. The colors of the two cables would be different to make sure you connect them to the right jacks.

Step 2 – Single Voice Coil or Dual Voice Coil Subwoofer

Your subwoofer may be either a Single Voice Coil or a Dual Voice Coil (popular in car audio systems) woofer. Dual Voice Coil subwoofer offers multiple wiring options, such as parallel, series or independent. Within a Single Voice Coil, a single set of terminals would include positive (red) and negative (black), whereas Dual Voice Coil has two such sets of terminals.

Step 3 – Connecting to the Amplifier

The biggest advantage of passive subwoofer is that it gives you an option to work with different amplifiers according to your needs and required features, which is not possible in active subwoofers. Make sure you amp is powered off before starting. Now connect the RCA cables already connected to the subwoofer’s input jacks to the amps. The jack at the amplifier would either be labeled LFE (Low Frequency Effects) or Subwoofer Output, and this is where the RCA cable is plugged into. Note that we are only discussing how to connect a single subwoofer, but multiple subwoofers can be connected to an amplifier.

 Step 4- Connecting Amplifier to the Speakers

Eventually, connect the amplifiers to the speakers. At the back of your amplifier you will find “main” or “front” speakers outputs. Connect two speaker wires to these outputs, one to each. The bare end will go directly into the speakers. Make sure the “left” output is connected to the left speaker and the “right” output goes into the right speaker of your stereo. Often there is a polarity defined, in which case make sure the positive of the speaker goes into the positive of the amplifier, and the negative terminal of the speaker goes into the negative of the amplifier. Work with your receiver’s bass management/cross over settings for optimum sound and bass control. This will give a complete surround sound system, with the main speakers as well as the subwoofers in place. Connect the amplifier to the power supply and double check all the wiring before turning it on.

Got a New Project You're Proud of?

Post it on Your Projects!