Beginners to audio know there are many subtle nuances to how sound travels across space, whether the space is large, small, wide, or long. How you set up speakers, for example, makes a big difference. The placement of speakers is crucial in terms of how everything will sound to the listener's ear, and a common question that home theatre beginners ask is where the subwoofer should sit, with many wondering if it's possible to sit behind you.
You can put a subwoofer behind you or a piece of furniture, however, this may not be the best place to put a subwoofer if you want to enjoy immersive bass that is smooth and clear. There are a few reasons for this that you should probably know about.
While it might seem like it doesn't matter, it's great to understand how subwoofers work because then you'll have a better idea of how to place your speakers for optimal performance, and also how to protect them which we've explored before. Speaker systems, especially those with subwoofers, have different units for different frequency ranges, and these frequency ranges are important for getting the best sound out of your system.
How do Subwoofers Work?
The purpose of a subwoofer, like the Skar Audio Dual 10″ from Amazon, is to reproduce lower frequencies that a regular speaker isn’t designed to generate. These frequencies, bass, and sub-bass range from 20 – 200 Hz for consumer models, however, professional components are 100 Hz and below to produce the thumping bass excepted at live concerts.
Subwoofers reproduce sound by their design. It won’t deform due to the air pressure necessary to produce lower frequencies. Unlike woofers and tweeters that are often constructed from plastic, subwoofers are often housed in wooden cases, boxes, or other sturdy material, because wood is a great sound conductor.
You can’t use subwoofers without woofers. If you place an external subwoofer anywhere by itself, all you’ll hear are bass and sub-bass. In most home sound systems, this isn’t a problem. The subwoofer is usually mounted in the speaker cabinet or soundbar because this way is easier to set up for a surround system. All of the components are contained in a single unit.
Types of Subwoofers
There are two types of subwoofers, active and passive. The difference between the two is in the amplifier. Active subwoofers, like the Edifier R1280TS from Amazon, come with amplifiers, while passive ones need an external amp. Put simply, you’ll need an amplifier of some kind if you want the subwoofer to work properly. The amplifier is just the component that powers the subwoofer.
- Standing waves occur when there’s too much bass hitting the walls. The effect is audio that lacks definition. Instead of the full spectrum of lower frequencies, you only hear one note.
- Bass nulls are exactly what it sounds like. There are gaps in the audio resulting in “dead spots”.
Where the subwoofer is placed determines audio quality, and also how you position it changes the way it sounds as well. For example, it's possible to place a subwoofer on its side, but there are a few reasons you wouldn't want to which we've talked about before. You don’t want the sound bouncing around the room. It will create one of two effects when the sound waves hit each other.
How Should Subwoofers Be Placed
As we have mentioned before, where the subwoofer is placed determines audio quality, and also how you position it changes the way it sounds as well. For example, it's possible to place a subwoofer on its side, but there are a few reasons you wouldn't want to which we've talked about before. You don’t want the sound bouncing around the room. It will create one of two effects when the sound waves hit each other.
- Standing waves occur when there’s too much bass hitting the walls. The effect is audio that lacks definition. Instead of the full spectrum of lower frequencies, you only hear one note.
- Bass nulls are exactly what it sounds like. There are gaps in the audio resulting in “dead spots”.
To avoid these audio problems, you need to pay attention to the room’s dimensions and furniture placement. Some frequencies are much louder and stronger than others, for example, a low-end frequency or a sub-bass frequency is very boomy. These are probably the average person's favorite because they are responsible for shaking rooms and cars.
Put the Subwoofer Where It Sounds Best
If there aren’t any limitations on where you can place a subwoofer, you won’t have to worry about standing waves and bass nulls. Instead, you can do a ‘trial and error method. You’ll place the speaker in a spot and move around the room. Listen to areas the audio sounds best and mark it with chalk or tape. It might take a while to find the best spot, but it’s worth it when you hear the audio.
Put the Subwoofer Behind You
Putting a subwoofer behind a couch or your favorite chair will give you amazing bass. The audio is smooth and clear, with deep, thumping bass. While the audio from your vantage point is exceptional, it isn’t the same for everyone in the room. They might have audio interference due to the sound waves bouncing off of the furniture and walls.
Put the Subwoofer In Front of You
This is somewhat of an unofficial rule for subwoofer placement. If you’re in doubt, put the subwoofer in front of the room. Some audiophiles feel, if a subwoofer is a few feet away from the wall you’ll have improved sound quality. It reduces the risk for standing waves and nulls helping to ensure great quality bass.
Put the Subwoofer in a Corner
Putting a subwoofer in a corner isn’t the best option. There’s always the risk for nulls and standing waves, and it's just not a good position for the speaker to be in because it inhibits the flow of low-end frequencies. If it’s your only option, there’s a step you can take to minimize any problems with sound quality.
If the subwoofer is in a cabinet, towards the rear, you can block the opening with rolled-up socks or new tennis balls. Some speaker manufacturers also offer plugs that are designed to prevent sound waves from bouncing off walls. Another option is to move the subwoofer out of the corner a few inches or more as possible.
Put the Subwoofer Under a Couch or Table
As your last option, you can place a subwoofer under a chair, couch, or table. However, if your sub isn’t equipped for frequencies 120Hz and higher you’ll hear gaps in the audio. The low hanging surface, along with the back one, will affect sound waves and how audio is reproduced.
Placing Multiple Subwoofers
If you have multiple subwoofers, bass and sub-bass can sound amazing if the components are in the right places. A growing number of consumers are choosing to install 4 subwoofers, instead of only one or two. Using multiple subwoofers reduces your chances of encountering issues with the audio, primarily audio delay, also called latency.
An audio delay occurs when the sound waves from the subwoofers don’t reach the center of the room at the same time. Instead of getting a mix of all the lower frequencies, you only hear one or two at a time. Sometimes the time delay isn’t that noticeable. However, there are times when the audio will sound “off”, distorted, or muffled. Placing the subwoofers in a way that works with the room’s dimensions will help prevent this and other problems.
There are three placement methods you can use with the subwoofers. All allow for smooth, even sound if you follow a few guidelines. The three ways are,
How to Place Multiple Subwoofers
- Corner placement. The subwoofers are placed in each corner of the room. Optimally there are two subwoofers in front and two in the rear.
- ½ placement. Instead of in the corners the subwoofers are placed in the middle of each wall. There is a subwoofer in front, behind, and on either side.
- ¼ placement. The subwoofers are placed ¼ of the way out from each corner. While the sound is rich and full with fewer adjustments, not everyone wants their audio components in plain view.
Regardless of which placement option you choose, chances are you’ll still need to make a few adjustments for optimal sound quality.
How to Optimize Sound Quality
Even when the subwoofers are evenly placed around the room, sound waves can bounce off walls resulting in audio delays. These simple guidelines will ensure the lower frequencies always sound smooth, rich, and clear.
- The front and rear subwoofers must have the same phase response, otherwise, you will have time delays.
- You want to make sure that the front and rear subwoofers are placed symmetrically to each other. This way the subwoofers are reproducing mirror images of the sound waves that reach them, resulting in full, smooth lower frequencies.
- After placing the subwoofers adjust the levels so the front matches the rear. If you have subwoofers on the sides of the room, adjust their frequency levels until they’re the same.
- Adjust the delay on the subwoofers behind you for cancellation at the wall. This ensures that the audio will reach you, instead of bouncing around the room.
If you follow these guidelines, the subwoofers behind you will sound as great as the audio components in front.
Effects of Placing Your Subwoofer Behind You
Sometimes your only option is to place the subwoofer behind you, and the audio can still sound great. However, other placement options can improve sound quality for everyone in the room. If you want the best audio experience with the lower frequencies, try installing multiple subwoofers around the room.
Four subwoofers will give you immersive sound and it’s not difficult to install the components. You might have to do a little fine-tweaking but when you’re finished, bass will be deep and clear throughout your entire home theater area. Just make sure you do a little trial-and-error to find the sweet spots.
