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 will determine the subwoofer’s size — the bigger the room the bigger the subwoofer. The power ratings and the ohm load are a few of the things that you would need to consider in choosing an appropriate amplifier for your subwoofer.
Step 1- Connect the RCA Cables
Cables will be used to connect the subwoofer 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 cable for the output. For the stereo output, you will need two cables. The colors of the two cables will be different to make sure you connect them to the right jacks.
Step 2 – Understand Your Subwoofer
Your subwoofer may be either a Single Voice Coil or a Dual Voice Coil (popular for car audio systems) woofer. A Dual Voice Coil subwoofer offers multiple wiring options, such as parallel, series or independent. With a Single Voice Coil, a single set of terminals would include positive (red) and negative (black), whereas the Dual Voice Coil has two such sets of terminals.
Step 3 - Connect to the Amplifier
The biggest advantage of a 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 for active subwoofers. Make sure your 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. 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 - Connect Amplifier to the Speakers
Eventually, connect the amplifier to the speakers. At the back of your amplifier, you will find “main” or “front” speaker 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 terminal of the speaker goes into the positive end of the amplifier, and the negative terminal of the speaker goes into the negative end of the amplifier. Work with your receiver’s bass management/crossover 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.