On the A/V awesomeness scale, few components compete with the subwoofer. There’s just something primal about a box made for the sole purpose of rattling your bones and delivering low tones. We think everyone should have at least one – but two is better. Unfortunately, as awesome as subwoofers are, they can be mighty fickle.
Unless you’ve got a firm handle on the science of acoustics and a deep understanding of how your A/V equipment works, placing and setting up a subwoofer for the absolute best performance can and sometimes will wind up being a sweaty case of trial and error. Though it is impossible for us to anticipate and respond to the myriad variables that your distinct room will introduce (things like floor type, ceiling type, room dimensions, etc.) what we can do is point you in the right direction. Our aim is to give you the tools and understanding you need to figure this out on your own. There will still be some trial and error involved, but at least it will be educated trial and error; and at the end of it all, you’ll be enjoying better bass. Yay for bass! Now let’s do this.
Why a subwoofer?
You get way more bass for your dollar from a box purpose-built to belt it out. Subwoofers are less obtrusive than the sort of floor-standing speakers with drivers big enough to pull off the same task. Also, they have dedicated power on board, lessening the strain on your A/V receiver or multi-channel amplifier. In short, they are a more efficient route to satisfying low end needs. The proper integration of a subwoofer will also improve the overall sound quality of your system; you should notice an increase in the depth and width of your system’s soundstage, and your primary loudspeakers should sound less constrained because they’ve been relieved of a lot of heavy lifting.
The importance of placement
Most folks don’t think of it this way, but when you listen to an audio system, what you’re really hearing is the effect your room has on the audio system. Walls, windows, and furniture all color the sounds that you hear, but bass frequencies are particularly sensitive to room factors. That’s why where you put your sub is really important.
One of your subwoofer’s biggest enemies are parallel surfaces – you know, those crazy things called walls in your living room or den. Bass waves are omni-directional, so they tend to bounce all over the room. When they reflect off your walls, they will often bounce back into one another, creating one of two scenarios: standing waves or bass nulls.
While we concede that a corner is often the most convenient option, it is rarely the ideal option.
Standing waves (which are influenced by the size of your room and the length of the sound wave) are an excess of bass energy. This occurs when a specific frequency is reinforced by room factors or by similar wavelengths occurring at roughly the same time and place. What you hear in such a case is that “boomy” effect or “one-note bass” which lacks definition or tautness. On the opposite end of the spectrum are bass nulls, which happen when reflecting waves cancel one another out, leaving you with a dead spot.
In order to deal with room acoustics and the effects they have, you can choose to work either with the room or against it. Working with the room involves acoustical treatments along with smart subwoofer placement and adjustment. Working against the room can involve anything from fancy EQs to room correction software. We prefer the former tactic to the latter when possible.
Where to put it
As a general rule, placing your subwoofer in a corner or close to the wall is going to result in more bass, but not necessarily the best bass. Small, low-powered subwoofers like the ones that usually come with home-theater-in-a-box systems and soundbars tend to use small drivers paired with low-powered amps and, thus, tend to benefit from some boundary reinforcement. Unfortunately, all you’re really getting is more of the same crappy bass. While we concede that a corner is often the most convenient option, it is rarely the ideal option.
Subwoofers with larger drivers and more powerful amps don’t need to lean on your wall for help. In fact, high-quality subs tend to sound their best when pulled at least 8-12 inches from any wall. Subwoofers also work better in the front half of your listening space, placed closer to your front channel loudspeakers which helps with timing delays and phase cancellation.
Here are some handy suggestions for where to place your sub based on what sort of flexibility you have, and what to expect from it living there.
Carte Blanche: So you can put your sub anywhere? Well, congratulations to you. No, seriously, that’s awesome because so few people have the flexibility you do. But, since you’ve got it like that, here’s what we suggest: Move your listening chair or couch away from where you normally sit. Now, stick your subwoofer right where your chair used to be and cut loose with some heavy-duty bass content. Walk and crawl around the room, listening carefully for where the bass sounds most even and defined. It’s not just about that visceral kick to the gut. You want to hear the timbre (tonal quality) and texture of the notes. Put a piece of tape down on the floor when you notice things are sounding good, then move to another spot. Keep doing that until you have 3-4 options.
Anywhere in the front: Follow the “Rule of Thirds” for subwoofers. The idea is that, by placing your subwoofer a third of the way into your room as measured from a wall, you reduce the instances of standing waves and nulls. Mathematically speaking, by following this guideline, the odds that where you sit will be a” good bass spot” are increased.
It has to be in a corner: Look, nobody wants to put baby in a corner, but sometimes you have to. Here’s what you can do to mitigate problems that come from putting a sub in a corner. First, if your subwoofer is ported on the rear of the cabinet, you can stuff the port with tennis balls, rubber balls, or even rolled up socks to seal the cabinet and cut down its interaction with the wall behind it. Many manufacturers now provide custom plugs with their products so that you can experiment with the sound. Second, move the subwoofer at least 6-8 inches out from the corner. Bribe your buddy with a few microbrews to literally crawl along the floor for you; move the subwoofer a few inches in each direction to find the ideal spot. Just make sure he doesn’t get crazy with the volume.
Under a couch or table: This is not the worst plan in the world, but expect a hole in the sound if you have really small satellite speakers that depend on the sub for frequencies over 120Hz.
Inside another cabinet: We understand that, sometimes, certain circumstances can’t be surmounted. But you need to know that this is the worst possible scenario. Putting a sub inside another cabinet pretty much defeats the purpose of a subwoofer. Those non-directional low frequencies need room to breathe in the room, and you’ve just crammed them in a closet and shut the door.
Inside the wall: This is becoming more and more popular with custom installers, and while there are some really good in-wall subwoofers available from JL Audio, Paradigm, and B&W, this is not the type of product renters should even consider installing – unless you’re really, really good at repairing drywall, and even then you risk seriously angering the neighbors. In-wall subwoofers need to be professionally installed with special boxes that are designed to hold the subwoofer cabinet in place and isolate it from the rest of the room. Done properly, it can be an effective solution. One thing to remember: in-wall subwoofers are really expensive because they often require external amplification, crossovers, and a lot of labor to install them properly.
Automatic vs manual calibration
Most mid-range and up A/V receivers these days feature automatic room correction (ARC) of a sort, and while they do a decent job of detecting things like speaker distance and channel levels, they are notoriously inaccurate when it comes to determining crossover settings. For the purposes of this discussion, the term crossover refers to the point at which a speaker stops producing bass and the subwoofer takes over. As you can imagine, this setting is critical for getting the best possible bass response in your room.
Some ARC software offerings do a better job than others. Anthem’s ARC is by far the most effective we’ve seen, followed by Sonos Trueplay, which is more effective mainly because it only has to deal with a handful of Sonos speakers. Yamaha’s YPAO, Audyssey, and others are generally less effective.
Rather than rely on the automated system, determine the best crossover settings for your system yourself. You can still use automatic calibration for the rest of your speakers, and only manually calibrate the subwoofer. For more a closer look at just how to do that, see below.
Dialing it all in
Once you have found the best location for your subwoofer and made some essential system settings, you need to dial in the sub’s phase, crossover point and volume. The smaller the speaker, the higher the crossover frequency is going to be. If you don’t already know what your speakers are capable of, look up the frequency response specs for your speakers in their manual or online. Now take that number, and bump it up by 10hz.
Setting the crossover dial is easy: crank it all the way up. This will essentially defeat the sub’s internal crossover, allowing your A/V receiver to take care of the task. If you are not using an A/V receiver or preamp/processor to control your crossover (perhaps using line level inputs for a stereo rig), then set the crossover as close as possible to the point at which you want the sub to start producing bass. This is usually based on the speaker’s rated low-frequency extension. You can also have your buddy (Is he still around? Hope he didn’t drink all the beer) start with the crossover dial all the way down, and slowly bring it up until you feel like you have a good blend between your main speakers and the sub.
Next, play some bass-intensive music (movies are unreliable and don’t give your ear something familiar to latch onto). If while listening you notice an obvious drop in bass energy (or what we like to call “suck-out”) near the frequency at which your subwoofer and main speakers crossover, you need to make adjustments to your phase control. Play the same track over and over again and listen while a friend changes the phase setting (this could be a continuous dial or a simple switch with one or two positions). Stop when you’ve arrived at the setting that results in the fullest sound. If adjusting phase doesn’t rid you of your suck-out, then the problem may be due to bad placement. Go back to the placement section of this guide and try again.
Rather than try to out-muscle the effect your room has on sound by tweaking the sound itself, tweak your room.
With regard to volume, it is a mistake is to crank your subwoofer’s volume dial to its maximum setting. Instead, set the volume dial to about 75 percent or so and adjust the subwoofer output level from your AV receiver or preamp/processor instead. Turn the volume up and down in wide swings at first, then in smaller increments until you reach the point at which you don’t really notice the subwoofer. It should essentially “vanish” into the sound, creating the illusion that your entire system is reproducing all of that bass response. A well-integrated subwoofer will also expand the soundstage in terms of both depth and width.
Work with your room, not against it
Here’s where we get into working with your room instead of against it. Rather than try to out-muscle the effect your room has on sound by tweaking the sound itself, tweak your room so it doesn’t affect the sound in the first place. One of the easiest ways to do this is to put some kind of acoustic treatment in the corners of the room. You can go with bass traps or some other purpose-built sound-absorption device, but these can be expensive … and ugly. To bust up the acoustical mess in your room’s corners, try placing a piece of furniture (avoid glass or large flat surfaces – that’s what we’re trying to fix, here!) or a large potted plant (it can be fake) in the space. Shelves filled with books are great for this sort of thing, too.
If you have hardwood or concrete floors, investing in some carpet or a rug will help tremendously. For those with hardwood floors, the use of floor spikes and protective discs under your sub will make a difference. If you want to spend more money, you can also consider a dedicated subwoofer stand (yes, they make those).
Before we share our final bit of advice, bear in mind that we’re not salespeople – we have absolutely no interest in milking you of your hard-earned money. What we’re about to tell you is true. We’ve tried it ourselves, and the results are fantastic.
You should have two subwoofers.
Seriously, you really should. One of the best research papers ever written on this topic was penned by Todd Welti, an acoustic technician at Harman International (the company that makes Harman/Kardon electronics, JBL speakers, etc.), and this was his conclusion. We understand that, for domestic reasons, the multiple subwoofer route is frequently less than ideal, but we’re here to tell you it sounds spectacular. If you can swing it, you should. Multiple subs won’t fix the issue of standing waves, but it will give everyone in the room a better sense of bass response by eliminating the potential for those null spaces we mentioned earlier.
Go forth and be moved
It may take a few passes – or even a few days – to get things just right. You might even upset a few neighbors or roommates along the way. But that glorious moment when your subwoofer is delivering the kind of bass that makes your spine tingle is worth any associated work and grief. Have fun!
Source : https://www.digitaltrends.com/home-theater/how-to-setup-a-subwoofer/