A subwoofer is to sound what wasabi is to sushi. Use it carelessly, and it’ll overpower everything else. But use it judiciously, and it can make the whole experience much more satisfying.

Subwoofers are far more complicated to connect and fine-tune than anything else in an audio system. The acoustics of your room have a far greater effect on subwoofer performance than on your other speakers. Subwoofers often must be connected to different AC outlets than the other components in the system, and most audio systems don’t include dedicated subwoofer connections. But millions of people have set up subwoofers to their satisfaction, and you can, too.

We’ve simplified the process into five steps, all of which conveniently begin with a C: connect, controls, crawl, combine, and check. In nearly 30 years of reviewing and measuring subwoofers, I’ve found that this method gets almost any subwoofer working well with almost any speaker system, no matter what other audio gear I’m using. It’ll work with any of the picks in our Best Budget Subwoofer guide—and with any other conventional subwoofer, too.

1. Connect

If you are using your subwoofer with a home theater receiver, the connection is simple: Just run an audio interconnect cable like this one from the receiver’s subwoofer output to the subwoofer’s line input (pictured above). If the subwoofer has an input labeled LFE, use that one. If it just has right and left stereo inputs (line level), use either one.

If you are using your subwoofer with a stereo receiver that lacks a subwoofer output (and many of them do), you can connect the subwoofer using an extra set of speaker cables, as shown above—provided the subwoofer has speaker-level (speaker wire) connections, as the picks in our Best Budget Subwoofer guide do. Typically, you’ll run the left and right speaker cables from the receiver to the sub, then from the sub to the speakers. The subwoofer’s manual will likely include diagrams that show the connections clearly.

If you are using your subwoofer with a computer speaker system, your speaker system may have a subwoofer output or a set of line outputs that can be connected to a subwoofer. If neither is present, get a Y-adapter like this one. Plug the Y-adapter into your computer’s audio output, then connect one leg of the Y-adapter to your computer speakers using a 3.5 mm cable like this one (most computer speakers include this cable), and connect the other leg of the Y-adapter to the subwoofer’s line inputs using a 3.5-mm–to–RCA cable like this one.

Hum problems are common with subwoofers because people often plug the subwoofer into a different AC outlet than the rest of the audio/video system; if the two outlets are on different circuit breakers, a "ground loop" can result, which produces a 60 Hz hum. Sometimes hum can even occur when the sub is plugged into the same outlet or outlet strip.

To fix a hum problem, first check the audio connection between the subwoofer and the receiver. A damaged or partially disconnected cable can produce hum. If the cable is in good condition and the connections are solid, and if your subwoofer has a detachable AC cord that you can flip in its socket on the sub, try flipping the connector. If your sub’s AC cord is permanently attached or not designed to be flipped, and the sub’s plugged into a different outlet, try plugging the subwoofer into a power strip shared by the rest of the audio/video system. If this trick eliminates the hum, but keeping it connected this way permanently isn’t practical for you, try using an isolation transformer on the cable going from the receiver to the subwoofer or using a wireless subwoofer transmitter.

2. Controls

Inexpensive subwoofers usually have just two knobs you need to adjust: volume and crossover frequency.

The crossover frequency determines the highest notes the subwoofer will play. Set the frequency too high and it could make Ariana Grande sound like Vin Diesel because part of her voice is coming out of the subwoofer. Set it too low and there will be a sonic "hole" between the subwoofer and the speakers, and Vin Diesel may start to sound a little like Ariana Grande.

The idea is to get the subwoofer to pick up right where the speakers leave off. You can generally find the lowest frequency the speakers are rated to play in the spec sheet on the manufacturer’s website or in the owner’s manual. For example, the spec sheet for the Q Acoustics 3020i, which we tested for our guide to the best bookshelf speakers for most stereos, shows the speaker as having a rated frequency response of 64 Hz to 30 kHz. In this case, you should set the subwoofer’s crossover frequency at 64 Hz or a little higher.

Set the frequency too high and it could make Ariana Grande sound like Vin Diesel because part of her voice is coming out of the subwoofer.

Be forewarned, though—some manufacturers get a little optimistic with these specs. For example, the spec sheet for the Audioengine HD3, which we tested for our best wireless powered bookshelf speakers and best computer speakers guides, rates its response down to 65 Hz, even though the HD3 is much smaller than the Q Acoustics 3020i and has a tiny 2.75-inch woofer. Your best bet is to set the subwoofer crossover frequency to match the rating of the speakers, then turn the frequency higher if you hear a "hole" between the subwoofer and the speakers—for example, if Vin Diesel’s voice sounds thin and wimpy, or if the crashes and explosions in action movies don’t have the impact that they probably should.

Note that if you use your subwoofer with a home theater receiver, you should set the subwoofer’s crossover frequency control to the maximum and use the receiver’s subwoofer crossover settings. The standard crossover frequency in home theater systems is 80 Hz. If your speakers are small—with woofers measuring 4 inches or less—you might want to set the frequency at more like 120 Hz; this will relieve your speakers of the need to produce low frequencies, so they’ll be able to play a little louder, and the system will sound clearer. If you have larger speakers, such as tower speakers, you might prefer the way a 60 Hz crossover frequency sounds. In this case, there’s no hard-and-fast rule because the acoustics of your room will have a large effect on the results.

Now you need to set the level (or volume) of the subwoofer relative to the other speakers. If you’re using a home theater receiver, it has a built-in test tone that will help you set the subwoofer’s level. In this case, it’s usually best to leave the subwoofer’s volume control about halfway up and adjust the volume of the subwoofer using the receiver’s controls. If setting the sub’s volume halfway up doesn’t give you enough volume, try turning it up about three-quarters of the way and then fine-tuning the level with the receiver’s subwoofer level control. If you have to turn up the level on the subwoofer past halfway, don’t worry about it. Practically all powered subwoofers have an internal limiter that will protect the driver and amplifier. Unless you’re hearing gross amounts of distortion, there’s no problem.

If you’re using the subwoofer in a stereo or computer system, just set the subwoofer volume so that it sounds the best from the chair you usually sit in to listen. The sound should be neither boomy nor thin. You can also change the subwoofer volume on the fly to suit whatever music or movies you’re listening to. There are no rules here.

Most subwoofers also have a phase control—a switch or knob that adjusts the timing of the bass slightly so that the subwoofer is more in sync with the main speakers. In some cases, this can help the subwoofer blend better with the main speakers, but the setting of this control usually isn’t critical. Try different settings and see what sounds best to you; if you don’t hear a difference, don’t sweat it.

Note that most home theater receivers have automatic room-correction technology that should, in theory, balance your subwoofer with your main speakers and adjust the subwoofer’s sound for the best performance in your room. There’s no harm in trying this out or sticking with the results if you like the sound. However, this technology is notoriously unreliable and may even make the sound worse. Read our best AV receiver guide for more information.

3. Crawl

The location of the subwoofer and listening chair in your room will probably have a greater effect on the sound than your choice of subwoofer. Put it in the corner, and it’ll sound boomy. Put it somewhere else, and some bass notes will be boosted while others will be somewhat muted. And the effects will differ depending on where you’re seated. Fortunately, your ears can’t detect where deep bass sounds come from, which means you have a lot of flexibility when it comes to placing your subwoofer.

If you want the best sound from your subwoofer, there’s a time-honored technique you can use to find the optimum place for it. Put the subwoofer in the chair you most often sit in when you listen (no, really) and play a tune with a melodic bassline, like Steely Dan’s "Aja." Now crawl around the room with your head near the floor (yep, we’re still serious) and find the place where the bassline sounds the most even. That’s the spot where you want to place the subwoofer.

Unfortunately, this placement will deliver the most even bass only for that one seat. For many audio enthusiasts, that’s fine, because other people in the room with them might not be so picky. If you do care about giving everyone the best sound, go ahead and do the crawl, then listen to the bassline again from your primary listening seat and then the other seats. Then move the subwoofer around until you find the best compromise. Or better yet, move on to the next section of this article.

If sound isn’t so important but appearance is, just put the subwoofer wherever it’s convenient. It should still sound pretty good, regardless of location, if it’s adjusted correctly.

4. Combine

If you care about how even the bass sounds in all the seats in your room, there’s an easy, although usually more costly, solution: Buy two subwoofers instead of one. Placing one subwoofer in the front left corner of your room and a matching sub in the front right corner will provide smoother, more consistent bass response as you move from seat to seat. In a widely heralded research project (PDF), scientists from Harman International (parent company of JBL, Infinity, Revel, Mark Levinson, and a host of pro-audio brands) determined that placing four subwoofers in a room (one in each corner or one in the middle of each wall) produced the most consistently smooth bass throughout a room. They also found that two subwoofers (in corners or in the middle of opposing walls) didn’t deliver quite as good a result but were still far better than just one subwoofer—and obviously a far more realistic solution for most people. Considering the low prices of our top picks in our guide to the best budget subwoofer, buying two subwoofers can be a practical alternative for more serious listeners.

That’s not to say two subs are the best solution for everyone. In a considerably less heralded research project I did for Sound & Vision magazine, my listeners and I (including Wirecutter’s Lauren Dragan and Geoffrey Morrison) confirmed the Harman International results when multiple seating positions were considered, but we found that for a single listener (or a listener who doesn’t care what everyone else in the room hears), it’s generally smarter to spend your money on one large subwoofer than two smaller ones. This way, you get more rock-’em/sock-’em bass for your bucks.

Hardcore enthusiasts tend to use a subwoofer equalizer to adjust the sound of one of the two subwoofers so that it corrects the flaws in the response of the other one, but at that point you’re getting into a much more expensive system and (much more complicated setup) than we’re talking about here.

5. Check

When I worked at Dolby Laboratories—the company that’s done more than any other to establish the technologies and standards for home theater sound—an audio journalist asked me how to achieve the most accurate balance between a subwoofer and the main speakers. Within Dolby’s huge, well-funded research department, I found one engineer who was considered the company’s top subwoofer expert. “So what should I tell them?” I asked after he described from memory the results of eight studies on the subject, some of which dated back decades. “Just tell them to set it by ear,” he replied.

As the Dolby engineer implied, the large number of variables in subwoofer setup—volume level, crossover frequency, the characteristics of the main speakers, the room acoustics, and the subwoofer’s own idiosyncrasies—make achieving a “perfect” setup practically impossible. Many home theater enthusiasts get a little closer to perfection by using a measurement microphone and a USB interface (or a USB measurement microphone) in conjunction with the free Room EQ Wizard computer application to fine-tune subwoofer performance, and that’s what I do when I test subwoofers for Wirecutter. But that’s a lot more serious than most casual listeners will probably want to get.

A simpler, although much less precise, alternative is to use the real-time analyzer (RTA) function in a smartphone app such as AudioTool (for Android) or Audio Spectrum Analyzer dB RTA (for iOS). If you play pink noise (available from many sources, including YouTube) through your system, these apps will show you how smooth the bass response in your room is and how well the subwoofer is blending with your main speakers. Two caveats: Choose an app with at least ⅙-octave resolution, and do the measurements from your primary listening chair (or sofa).

Even if you do have measurement gear and the knowledge and patience to use it, the ultimate test of subwoofer setup is whether you like the sound. So when you’re all done, just sit back and listen to some of the movies and music you like. The goal is to get your system to the point where female voices don’t sound bloated and male voices don’t sound thin. You should also be able to feel couch-shaking impact during explosions in action movies without making the bass sound boomy in lighter music, such as most pop and jazz. Even after you get everything sounding great, you may find yourself adjusting the subwoofer volume frequently to best suit the movie or music you’re listening to.

And if all this seems like too much trouble, unplug the subwoofer for a minute or two and you’ll quickly realize why it was all worth the effort.