Want to transform your home audio setup and feel every beat? Adding a subwoofer to your stereo amplifier is one of the simplest ways to bring your sound system to life. A stereo amplifier powers your main speakers, delivering crisp highs and mids, but it often lacks the deep, punchy bass that makes audio truly immersive. That’s where a subwoofer steps in, handling low frequencies with power and precision to give your music and movies a fuller, richer sound. The good news? Connecting a subwoofer isn’t as complicated as it seems. In this guide, you’ll learn exactly how to do it — quickly and easily.
What You’ll Need
You don’t need much to connect a subwoofer — just a few basic components. Grab your subwoofer (active or passive), a stereo amplifier, and either speaker wire or an RCA cable. Depending on your gear, check whether your sub and amp use line-level (RCA) or speaker-level connections. With these in hand, you’re ready to go.
Identify Your Subwoofer Type
Active (Powered) Subwoofers
These have a built-in amplifier, making them ideal for most setups. They’re plug-and-play, offer simple connection via RCA, and give you control over volume and crossover.
Passive Subwoofers
These need external amplification. They’re less common in home use and require more setup, including matching impedance and using a dedicated amp or receiver.
Connection Methods
A. Using an Active Subwoofer with Line-Level Inputs
This is the simplest method. Connect the amplifier’s RCA pre-output to the sub’s line-in, set the crossover, and you’re done.
B. Using Speaker-Level Inputs
No RCA out? Connect speaker wire from your amp’s speaker terminals to the sub’s speaker-level input. The sub filters out the lows internally.
C. Connecting a Passive Subwoofer
Passive subwoofers require the use of an additional subwoofer amplifier to process the level, phase and crossover settings for correct tuning and integration. The passive subwoofer connects via speaker cable into the sub amp. The sub amplifier connects to your primary receiver/amplifier via an RCA cable. This method requires more gear but works well when done correctly.
Identify Your Subwoofer Type
There are two main types of subwoofers: active (powered) and passive. Active subwoofers have a built-in amplifier, making them much easier to set up—these are the most common in home audio systems. Passive subwoofers require an external amplifier and are more common in custom or professional setups.
Connection Methods
A. Using an Active Subwoofer with Line-Level Inputs
If your amplifier or receiver has a dedicated RCA or subwoofer output, this is the easiest and cleanest way to connect an active subwoofer. Run an RCA cable from the amp’s sub out to the subwoofer’s line-in input. Once connected, set the crossover frequency on the subwoofer to determine which low frequencies it will handle—typically between 80Hz and 120Hz depending on your main speakers.
B. Using Speaker-Level Inputs (No Sub Out on Amp)
If your amplifier doesn’t have a subwoofer or RCA output, you can still connect an active sub using speaker-level inputs if your subwoofer has them as not every model does. Run speaker wires from the left and right speaker outputs on your amp to the subwoofer’s speaker-level inputs. The sub will take the signal, filter the bass internally for its own use whilst passing on a full range signal through to your main speakers. This method ensures you can still integrate a subwoofer even with older or basic equipment.
C. Connecting a Passive Subwoofer (Less Common)
Passive subwoofers don’t have a built-in amplifier, so they require a separate subwoofer amplifier to function. Connect the subwoofer output from the dedicated amp to the external subwoofer amplifier for the passive sub. We then connect speaker cables between the sub amplifier and subwoofer. This setup is more common in custom installations that utilize in-wall subwoofers or professional systems and requires careful power matching to avoid damage.
Tips for Best Sound
Subwoofer placement can dramatically affect performance. Placing it in a corner often boosts bass response, but this can sometimes lead to muddiness—try different positions in the room to find the cleanest, most balanced sound. Once placed, adjust the subwoofer’s volume so it complements your main speakers without overpowering them. Set the crossover frequency to blend smoothly—usually between 80Hz and 120Hz. Also, check the phase switch (0° or 180°); toggling it can correct timing issues between the sub and your main speakers for tighter bass.
Common Mistakes to Avoid
Never connect a passive subwoofer directly to your amplifier’s speaker outputs unless it’s specifically designed to do so—it can damage the amp. Use the correct cables: RCA for line-level inputs or speaker wire for speaker-level connections. Avoid overloading outputs with multiple connections or mismatched impedance. Lastly, don’t ignore the subwoofer’s built-in controls. Properly setting volume, crossover, and phase is essential for getting clear, impactful bass that seamlessly integrates with the speakers The subwoofer should sound like an extension of your main speakers and not like a separate component.
Connecting a subwoofer properly depends on knowing your sub type and choosing the right method—whether that’s using RCA cables for an active sub, tapping speaker-level inputs, or powering a passive sub with a separate amp. Once connected, take the time to test placement, fine-tune volume and crossover settings, and experiment with phase to get the best possible sound. A well-integrated sub can completely transform your listening experience. If you’re unsure about your setup or need help troubleshooting, feel free to contact us and ask questions which you may have.