Subwoofers can be intimidating, to say the least. Not only are the bass notes they deliver often vastly more powerful than regular home theater speakers, but setting them up and getting reasonable sound can often be an exercise in frustration. Things aren’t helped when you search online; like a mysterious medical condition, you never quite know whether it’s a hangnail, or whether your entire foot is about to fall off. The online subwoofer community is huge, and enormously passionate, but it can often feel like you’re drowning in an ocean of information. Well, fortunately, you’ve come to a site run by people who make it their goal to explain things as clearly and simply as possible. In this, The Ultimate Guide To Subwoofers, we’re going to explain absolutely everything to do with owning one, including breaking down the jargon, talking you through the factors you need to know when making a purchase decision, and showing you the best spots to place it. You’re welcome.
 

Let's make the big black box a little less scary... | The Master Switch

Buying A Subwoofer:

Passive Vs Powered:

The first thing you need to know is that there are two types of subwoofers: passive and powered. The difference between them is very simple. Passive subwoofers require an external amplifier to work, while powered subwoofers have an internal amplifier, and just need to be plugged into the mains.

We aren’t really going to talk about passive subwoofers here. Firstly, they are far less common than powered subwoofers, especially in the home theater space - although there are some still available, like this Bose PS 28 III. Secondly, going into the process of matching a passive subwoofer with an amplifier is an entire guide by itself. Fortunately, we do have such a guide to matching speakers and amps, but in this guide, we’re going to be talking about powered subwoofers exclusively. The benefit of doing this is that it vastly simplifies the process of connecting your subwoofer to your A/V receiver: all you have to do is run an RCA cable between them (most receivers have a dedicated subwoofer output), and a power cable from the subwoofer to the wall socket. Boom. Done.

Trust us: it’s a good thing that the subwoofer is powered. You’re going to need a lot of power.

Subwoofer driver | The Master Switch

Front-Firing Vs Down-Firing:

So: you’ve decided to buy a powered subwoofer. Congratulations. You’ve only got about 10,947,084 models to choose from, and that’s just on the first page. Let’s narrow things down a little further.

Subwoofers are further split into two categories: whether they are front-firing or down-firing. Figuring this out is easy. If the driver (the big, circular speaker) is on the front of the unit, then it’s front-firing. Bottom? Down-firing. An example of the latter would be the Martin Logan Dynamo (although it can be ordered as a front-firing model), while one of the former is the JL Audio E112 E-Sub.

You might reasonably ask what the differences are between the two. There aren’t actually that many – not enough, given the variances between different rooms and different circumstances, to make a major difference. Bass frequencies are nondirectional, which means that it’s not going to make a huge difference which one you pick. However: if you’re planning on placing your subwoofer close to your main speakers, or underneath your TV (and we go into placement in more detail below), then it may be worth investing in a front-firer. Away from your speakers? At the side or in the corner of the room? Go for down-firing. But again, this isn’t a decision which makes a major impact, and in this case, consider what we are saying as general guidelines rather than hard rules.

The complicate things a little further, some subwoofers, like the Power Sound Audio S3601, actually fire in multiple directions – front and back. Models like this are pretty uncommon, though.

Subwoofers can be ported or sealed | The Master Switch

Ported Vs Sealed:

Another easy one – and this time, with a real difference to the sound.

Sealed subwoofers have a cabinet that is entirely enclosed, with no openings into its interior. Ported subwoofers have one or more openings, to allow the free-flowing movement of air. Put very simply: sealed subwoofers sacrifice a little overall volume and presence for a tighter, more controlled sound, while ported ones can pump out huge volume at the expense of a little clarity. Generally speaking, larger and more expensive subs tend to be ported, while smaller, cheaper ones do not.

If you’ve got a smaller room, and don’t need to blow the windows off, then it may be worth looking at a sealed subwoofer. If you aren’t going to be pumping things to huge volumes anyway, then it makes sense to invest in a little bit more clarity and depth to the sound, rather than plumping for huge volume. But if you have a bigger space, consider ported models.

You may also come across things known as passive radiators. Think of these as unpowered speaker drivers which are there to simply react to the air the main driver is moving. A subwoofer could have one or more of these in addition to the main driver, and they help with the articulation and expression of the sound. Passive radiators are almost always a good idea.
 

Wattage Explained:

No stat in audio is as misunderstood or as misleading as wattage. Let’s break it down as simply as possible.

Wattage, essentially, is a measure of electrical power - a way of expressing how much energy an amplifier (like the one in your powered sub) puts out. There will almost always be two measurements: RMS or Continuous Wattage, which is a measure of the power the amplifier can put out over a long period of time, and Peak or Dynamic Wattage, which is the amount it can put out in short intervals – always much larger. A well worn analogy is that of a runner, who can run at lower speeds for longer, or at sprints for short distances.

In very broad strokes: wattage ratings are a rough way to see just how loud a piece of equipment can go. But of course, it isn’t as simple as that, because as with all equipment, you are in control of the loudness. We can demonstrate that without even getting up from my seat. Imagine you’ve plugged in a 10,000 watt subwoofer, and you’ve turned it down to an almost inaudible volume. You’ve made that 10,000 watt subwoofer no louder than a whisper. A better way to think of wattage is as a range – The RMS and Peak Wattage represent just how much you can push your subwoofer before things start distorting. 

Of course, you might reasonably ask: if you have two subwoofers, one with an RMS and Peak of 500 and 1500 watts, and another with an RMS and Peak of 2000 and 3000 watts, then what’s the difference between them, given that they are both separated by 1000 watts?

The answer is in the nature of bass itself. Unlike higher frequencies, bass needs a lot of energy. The more wattage a subwoofer has, the more it will be able to provide that energy, at any volume. More wattage equals bass that is tighter, clearer, more well-rounded. It means that whether you’re rattling the windows or turning things down late at night, you’ll be able to get better sound. Once again: you control the volume. What you don’t control is the base-level clarity of the sound, and that’s where wattage can be a useful metric.

We agonised over this section. It is so, so easy to get lost in mathematical formulas and tables of figures when calculating exactly how wattage relates to decibel levels (read: volume). Ultimately, we decided that we’d keep things simple. If you have one takeaway here, it’s this: buy a subwoofer with a nice, wide gap between Peak and RMS, and get one with as many watts as you can afford.

You might also reasonably ask about how big a driver you need to get. Drivers are measured in inches, and generally speaking, a bigger driver equals better sound. We’d always say to get the biggest you can afford, but remember, bigger drivers equal bigger enclosures, too. Before that flatbed truck pulls up in front of your house, and you have to explain to your partner where you’re going to put your enormous SVS PB16-Ultra (full review here), it might be worth working out just how much space you’ve got to spare.

VIZIO wireless subwoofer. PS4 controller for scale | The Master Switch

Should I Go Wireless?:

There’s an easy dichotomy here. Most home theater or hifi subwoofers have wired connections, while many that come with soundbars, like the sub that arrives with the Polk MagniFi (full review here), are entirely wireless.

Wireless subwoofers have the advantage of needing absolutely no setup. They will already be slaved to the central unit, and all you need to do, in most cases, is plug them in. The crossover point (see below) is already set, so they take the difficulty out of initial setup, although you will of course need to work out where to put them, and they will need to be plugged into a mains socket. The downside is that in almost all cases, they don’t sound quite as good as wired subwoofers. This isn’t a universal rule, and the private wireless network they run on is certainly capable of transmitting some good low end, but we almost always prefer wired models.

This isn’t a decision we can make for you. The only thing we can say is that if you intend on having a 5.1 or 7.1 sound system, then we strongly recommend a fully wired subwoofer.

SVS PB16-Ultra | The Master Switch

Subwoofer Placement:

Front, Back, Side-To-Side:

Now that you’ve bought your subwoofer, you need to put it somewhere. And despite the fact that bass notes are unidirectional (they spread out evenly in all directions), where you put your sub can make a massive difference to the overall quality of the sound.

There are three main traditional spots to put a sub. The first is at the front of your room, underneath your centre speakers and TV, or just off to one side. In most cases, this will result in a harmonious blending with the other frequencies, especially if the sub is front-firing. The second spot you could try to put a sub, and one which will generally increase the perceived volume and clarity, is in the corner of the room. Mostly, but not always, this is the corner opposite your listening position – in other words, at the ‘front’ of the room. The third spot is halfway along the wall on one side of the room. We’ve had mixed results with this one, but in some circumstances – like when a room is not a traditional shape, or when the furniture placement makes things awkward – it can be a perfectly workable option.

However, there is a trick you can use to work out precise subwoofer placement. It just involves a little bit of back strength.

Place the subwoofer, fully connected, onto your listening position. That usually means sticking it on the couch. With a bass-heavy track playing, crawl around on the floor, pausing at various positions to see how the bass sounds. See where you like the sound the most, and put the subwoofer there. While this sounds simple in theory, it becomes extremely difficult when your sub goes past a certain size. You’re not going to be putting a massive cabinet with a 12” woofer on your couch – at least, not without the assistance of some friends.

There are a couple of other things you can use to tame the sound, including using EQ software on your receiver, or investing in foam bass traps. We’d say these are probably overkill, though. In almost all circumstances, the above tips should help you find the best spot to put your sub.
 

Doubling Up (Or Quadrupling Up):

One subwoofer is good. Two is better. Four is much, much better.

No matter where you place your subwoofer, there are going to be spots in the room where the bass sounds a little bit dull and characterless. Having multiple subs, placed at strategic points throughout the room, can help fix this. Think of it like peanut butter. Instead of having a single dollop spread thin across a slice of bread, you could put two dollops on it, and give everything a nice, thick coating. Try, for example, two subwoofers on either side of your TV, or in opposite corners. If you have four of them, try putting one in each corner of the room.

It does, however, pay to be aware of the downsides. Firstly, this obviously costs a hell of a lot more, and is only suitable for those with deep pockets. Secondly, it requires a lot more time to fine tune placement, not to mention the total faff of having to connect all these subwoofers up – either to a receiver with multiple subwoofer outs, or in a chain. You may even have to rely on external amplifiers, which can bring its own problems. Thirdly, you need to be quite careful with your volume. With this many subwoofers shooting power into the room, the low end can get overwhelming very quickly. Tread lightly.

The rear panel of the SVS PB16-Ultra | The Master Switch

Setting Things Up:

Plugging Your Sub In:

As we mentioned, powered subs are an absolute doddle to connect. Plug an RCA cable (make sure you have one long enough) into the line-in port in the back of the sub, and to the subwoofer out on your receiver. All that’s left to do after that is connect the power cable.

OK: sometimes it’s a little more complicated than that, a factor which largely depends on the rear panel of your sub woofer. The more expensive model is, the more likely it will come with a variety of switches and controls that let you adjust things at source.

Let’s tackle a few of these. If you see a volume knob on the back of your subwoofer – something that is rare but not unheard of – set it at about halfway. You can adjust it later, but you’ll be calibrating your sub to get the best sound, and the twelve o’clock position is where you want to keep it for now.

You might also see a switch or setting labelled phase. The simplest explanation for this particular setting is that multiple speakers sound better together when their drivers are moving “in phase” – as in, in sync with one another. The kicker is that it’s often quite difficult to figure out if you’ve set the phase correctly (phase is almost always available in two settings, 0° or 180°). You need to spend some time sitting in your listening position, listening to something with a lot of bass content, then flipping settings and listening to the same thing. Without putting too fine a point on it, one should sound “right”. If you can’t hear a difference, or both sound okay, then our advice is: don’t stress. Pick one setting, and leave it there. You can always change it back later.

You may also have various other ports on the back of your subwoofer, such as speaker outputs. For these, we are going to recommend that you consult your subwoofer’s manual. Every sub is different, and we don’t want to give specific guidelines here.

Use your receiver's setup to set the subwoofer crossover | The Master Switch

Setting The Crossover:

Welcome to the single most important thing you can do to make your subwoofer sound better.

As you've probably figured out by now, a subwoofer is designed to handle the low frequencies. But as well-designed as your speaker system is, it’s not actually sentient. It doesn’t know where those low frequencies begin. There’s a huge range where they occur, and until you tell it differently, your speaker system may be diverting some of the low-frequency information in your sound to your surround or front speakers - information that would be far better handled by your sub. Adjusting that point - the frequency below which all sound is sent to your sub - is called adjusting the crossover point.

Usually, the crossover is set using the on-screen setup for your A/V receiver. It should allow you to pick a particular frequency without too much trouble. To find the best frequency, what you need to do is go and look at the specs for the other speakers in your system. Every speaker has a frequency range it can comfortably reproduce. While they are completely useless when making a buying decision (something we’ve explained in detail here) they are very helpful for determining the crossover.

Let’s say you’ve got a set of speakers with a frequency range of 100Hz - 20kHz. That means your crossover point is 100Hz – that’s the point at which the speakers will stop being able to produce sound, which is where you need to bring your subwoofer thundering in the fill the gaps.

Once you’ve set the crossover (and run your receiver’s room calibration software, if it has any), there’s one last thing you need to do. Start playing a song with a lot of bass content, at a reasonable volume, through your system. Lower the subwoofer volume until you can just barely hear the bass. Then, very slowly, start to turn it up until the bass is at a comfortable but not overpowering level. Congratulations, you’ve effectively matched your subwoofer with your speaker system, and no matter how loud you turn up the overall volume, the bass will not overpower the other speakers. Remember: wall-shaking bass is all well and good, but the key here is synergy. You want an overall sound that is rich, powerful, and deep, without being uncomfortable. Setting the crossover and the volume is the best way to achieve that.
 

Three Great Subs You Can Buy Right Now:

SVS PB16-Ultra

SVS PB16-UltraAs far as we’re concerned, this is the Big One. The best out there. Other subwoofers may be louder, but we’ve yet to find any that can match the SVS flagship for clarity, depth or richness. This is the kind of subwoofer that has to be seen to be believed – not only does it produce huge sound, but it’s also the kind of thing you need a friend to help install. At 175lbs, it can take a real beating, and with an RMS of 1500 watts and a peak of 5000, there’s power for days here.

As we said in our full review, “Did it matter that our testing room was comically undersized for such a beast? Did it matter that it was unlikely to endear us to our neighbours? Did it hell. We wanted the PB16-Ultra from the moment we clapped eyes on it. And for the past month, it has come to absolutely dominate our lives. We are not exaggerating when we say we’ve never tested any piece of audio equipment quite like this.”
 

JL Audio E112 E-Sub

JL Audio E112It might look a little bit boring, but this is an absolutely terrific subwoofer that will complement any home theater system beautifully. For starters, it has phenomenal sound, with a weight that takes it above its price range in value for money. JL Audio have also fiddled with the cabinet design, producing something that keeps rattling at a minimum while maximising clarity.

It’s not an ideal model for beginners, as it does have some slightly confusing and unintuitive features. But if you don’t have the money to shell out for the SVS, then this is an easy layup. Go for it.
 

HSU Research ULS-15 MK2

HSU Research ULS-15 MK2Not everyone has thousands of dollars to spend on home theater equipment. If that’s you, then consider this baby from HSU Research. While it has an RMS wattage of “only” 600, it’s by some margin one of the best mid range subs you can buy.

Not only does it come with a huge range of flexible setup options, and deliver some block rocking, addictive sound, but you also get a very generous seven year warranty, which is something we’d expect from models that cost a lot more. At the time of writing, the ULS-15 is going for a shade under $800, which is highly affordable.
 

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