We all know that a subwoofer is an integral part of any home theatre setup. Surround sound and 3D audio is incredibly immersive, but without the rumble of a subwoofer, movies lose a lot of their magic. Have you thought about adding a subwoofer to your home audio system? Many people have a system that’s used primarily for listening to music. One of the more popular configurations these days is a stereo system with two speakers, perfect for enjoying records on a turntable, CDs, or your favourite music streaming service. Many people opt for a pair of bookshelf speakers, which offer that coveted stereo sound without taking up a lot of space.
The downside of home audio systems that use compact speakers—even very good ones—is a lack of bass response. The sound may be clean and in stereo, but it often lacks the low end punch that would make it perfect. The good news is it’s easy to fix that issue using the star of the home theatre setup. Just add a subwoofer.
Why a subwoofer is the solution to your home audio system’s lack of bass
If your home audio system is equipped with a pair of large tower speakers, you’re likely in good shape (although you could still add a subwoofer for extra bass oomph). However, bookshelf speakers are far smaller. That makes them much more convenient. But when it comes to producing low frequencies, smaller speakers run up against a stark reality. Bass is low frequency sound waves, and to generate those low frequency waves you need a large driver capable of moving large volumes of air.
Subwoofers are built around around large drivers, typically 8-inches, 10-inches, or 12-inches in diameter. In comparison, the woofer—the driver responsible for low and mid-frequency sound in most bookshelf speakers—might be anywhere from 4-inches to 6-inches. With many bookshelf speakers designed with a dual driver setup, that woofer is working hard to cover both the low end and the mid range.
Adding a subwoofer into the mix means your audio system now has a speaker that’s dedicated to low frequency sound, and equipped with a big driver that’s capable of producing those ultra lows.
In a home theatre system this adds realism to effects like explosions and revving engines. It gives depth and adds subsonic rumble. In a home audio system, the subwoofer adds new prominence and depth to instruments like the bass guitar and drums. The bass may sound decent in a compact stereo listening system, especially one equipped with a good pair of bookshelf speakers, but the difference with a subwoofer in the mix can be night and day.
Use the right cables
There are two ways that a subwoofer can be connected to an audio system and each method requires different audio cables. Some receivers and amplifiers have a subwoofer output jack. It’s usually labelled SUB OUT. In this case, connecting is as easy as using a RCA subwoofer cable to connect to the LFE or Line Input on the subwoofer.
However, many stereo receivers and amplifiers lack that subwoofer output. Especially systems that are used primarily for listening to records.
Many of these setups use a 2-channel stereo receiver or amplifier, often a vintage model that pre-dates subwoofers. However, these systems can still be used with a subwoofer. You’ll need to choose a subwoofer that offers speaker level input and output. This basically replicates the speaker jacks you see on the back of your receiver.
To connect the subwoofer in this case, you disconnect your speakers from the receiver and instead plug them into the Speaker Outputs on the subwoofer (they use the same left and right, black and red setup). Then you run a new set of speaker cables from the Speaker Input on the subwoofer, to the Speaker Outputs on your receiver. It’s recommended that you use fairly heavy duty speaker wire, 12-gauge to 16-gauge.
Positioning (and do I need two subwoofers for a stereo system)?
Positioning the subwoofer is important and it can be a bit of a challenge. Space is often the biggest issue to deal with. Subwoofers are big. They have large drivers, but also large enclosures to give those drivers room to move. Most subwoofers are powered, which means you need to be within range of an electrical outlet. The enclosures also require space for an amplifier (with powered subwoofers) and other electronics.
The size can have a lot to do with whether you choose a small subwoofer, or a large one.
The usual setup in an audio system setup is to use a single subwoofer, and to position it between the two speakers, ideally no more than a few metres away from the speakers. Set up like this, the bass will sound as though it is coming from the speakers, not the subwoofer. Technically, your setup won’t be true stereo for the low frequency notes, but you shouldn’t be able to tell. So you don’t need two subwoofers—although some people do choose to go that route.
The subwoofer is often placed near a wall. Models that have front bass ports can be placed pretty much against the wall. Units with rear bass ports need to be kept some distance from the wall or the airflow out of the vent will be disrupted, affecting the sound quality.
In my office setup (below), I have a pair of bookshelf speakers sitting on bookshelves (seemed appropriate), and the subwoofer is between them, hidden under my desk.
Adjusting the subwoofers settings: the key to great performance
Connecting the subwoofer and positioning it are the two basic steps, but now we get down to the fine-tuning. This is the step that will make or break your listening experience.
Home theatre receivers usually handle the subwoofer fine-tuning on their own, or guide your through the process. When you’re connecting to a stereo receiver (especially one that lacks a dedicated subwoofer output), it’s time to get manual. You may have to fuss with these settings for a few minutes to find the perfect combination.
On the back of the subwoofer you’ll find a crossover dial. It may also be called low pass. This is the setting that controls the point at which the signal from your stereo system is handled by the subwoofer instead of the speakers. Anything above the frequency you choose goes to your speakers, as usual. Anything below that level is now handled by the subwoofer.
The level you choose is going to depend on your speakers. For bookshelf speakers with a small woofer (4-inches or less), you’ll want to set that crossover fairly high. Try 120Hz. As the driver gets larger, the crossover can be lower, for example 100Hz for a 5-inch woofer. Then listen to music that features bass. If female vocals sound too deep, then the crossover is set too high and you should dial it back a bit. If male vocals or a bass guitar sound thin, then increase the crossover frequency.
Volume controls how loud the subwoofer is in relation to your other speakers. Have it too loud and the bass will start to boom and distort, especially as music volume is turned up. Too low, and music will sound thin, especially as it gets louder. Try setting the subwoofer volume at 50% and adjust from there.
This is a switch control (0 or 180-degrees) that ensures the subwoofer and woofers in your primary speakers are operating together in sync. Listen to music that features lots of bass while flipping between a phase of 0 and 180. Leave it at the one that sounds best. If you can’t tell the difference, go with 0-degrees.
Do I need a subwoofer with a soundbar?
Many people use a soundbar instead of a traditional stereo system. They’re great space-savers for TVs, but can also do double-duty as a home audio system. Do you need to use a subwoofer with a soundbar? For home theatre, gaming, and music listening applications, the audio is always going to sound better with a subwoofer.
I have an older—but very capable—soundbar in my rec room. It’s equipped with 21 small 1.5-inch drivers and a pair of 4-inch woofers. When I first installed it, I thought it sounded pretty good. However, it wasn’t until I picked up the matching subwoofer that the system fully lived up to its potential. It’s the subwoofer that brought the missing rumble, and provided the low end for window-rattling bass.
The complication is that many soundbars lack subwoofer or speaker output. If you already own a subwoofer, check its outputs—it’s also possible the manufacturer may sell a subwoofer specifically for use with it.
The good news is if you are shopping for a new soundbar, many brands including Samsung, Bose, JBL, Polk, Sony, Sonos, Klipsch, and Mission have soundbar packages that include a subwoofer.
Audio is too boomy, distorted or thin
If you’re lucky, everything will sound perfect when you get the subwoofer connected to your home audio system. However, it’s just as likely that there will be some tweaking required. If the audio seems boomy, distorted or thin, it’s time to fiddle with position of the subwoofer and the crossover, volume, and phase settings.
A subwoofer moves a lot of air. And sometimes that can can cause vibration, especially at higher volumes.
In my case, the subwoofer came with feet to help dampen vibration. However, on a wooden floor the vibration was still enough to rattle objects on my bookcases. It goes without saying that vibration wasn’t just annoying, it was really bad news for my turntable.
When vibration is an issue, the subwoofer needs to be isolated from the floor and/or walls. There are rubber and even shock-mount speaker feet designed for this purpose. I used a heavy sound isolation platform with integrated shock-absorbent feet. That completely eliminated the vibration.
Sometimes a low frequency background hum can be heard when the subwoofer is powered up. If you experience this, check the speaker cables and connections between the subwoofer and the amplifier. A bad connection or damaged cable can cause hum. The other cause is usually electrical. Try plugging the subwoofer into the same electrical outlet as the amplifier (using a power bar of necessary). If the two devices are already plugged into the same outlet, try plugging the soundbar into an outlet on a different circuit.
Enjoy your home audio system with its improved bass performance!
Time to sit back and enjoy listening to music that sound the way it was intended to, including powerful bass. Pink Floyd has never sounded better on my system since I installed a subwoofer.
The great thing about a subwoofer is that you can completely upgrade your audio system’s sound without the expense and hassle of replacing your existing speakers and components. And you don’t need to go with big tower speakers, you can make a system built around compact bookshelf speakers or even a soundbar sound impressive.