Why 2 subwoofers in a home theater
Before we take a look at the why and how of two or more subwoofers, let’s first define what they are and what they do. This may help to present a clearer picture of what this is all about.
A subwoofer is a speaker that reproduces the very low frequencies that are carried by normal speakers. Subwoofers behave as the bass section to the main speakers. They are designed to pick up the frequencies that, for whatever reason, the main speakers can’t handle and respond to them. This may be due to the physical limitations of the main speakers or the size and shape of the room that the speakers are in.
Since the purpose of subwoofers is to handle the very low frequencies, they need to be designed and built to handle them reliably. Subwoofers tend to be larger than main speakers, simply because of the need for additional space for the sound to resonate. They are bigger, heavier, and stronger than the main speakers.
You can get a significant improvement in bass level by adding a second subwoofer. This is because a subwoofer remains in the same place, so the bass energy never has to travel far to reach it. A single subwoofer, however, will reach peaks in the bass spectrum and then have to travel back to the average bass level, and then start again as the low-frequency musical signal ramps up. When two subwoofers are used, they act more as a single voice coil, reaching top level without travel and giving a much more even response.
The advantage of two subwoofers in a home theater system is that it makes the low-end sound output from the system more accurate and less distorted.
Advantages of 2 or more subwoofers
Better bass quality
Often a question asked about multi-sub setups is “how many subwoofers is enough?” The answer depends on your listening preferences and requirements. The more subs in your setup, the deeper the bass. Bass frequencies are omnidirectional, so multiple subs can be used to achieve better bass throughout the room.
While there is no such thing as too many subs, frequency response and room limitations restrict the number of subwoofers that will have their full potential maximized.
Widens listening area
Communication is one of the many factors that could limit you from enjoying your home theatre system. If you're watching a movie, you may not be able to hear it clearly when someone is standing near the amplifier. Installing two or more subwoofers in home theatres widens the listening area and ensures that everyone can clearly hear the dialogue, sound effects, and music.
Greater flexibility in audio output
As you know, most theaters do not have a setup like this for multiple subwoofers. They usually just have the one 12 inch subwoofer in the lower-left corner of the room, and that works out great.
But there is some overlap in this setup, and both of the subs are not always functioning simultaneously. For example, you could choose to watch a movie with a lot of action scenes and explosions sound effects. The action scenes might need that punch in the low end, and you would want your subwoofers to deliver. And yet, the explosions are sometimes so loud that they can't be played at high volume. So you might need to switch off the two subwoofers at some moments, depending on the scene.
This will be something to think about, since you may have to limit the sound delivery to one subwoofer, if not both, at certain points in time.
A second point is that if you have two subwoofers right next to each other, you will be able to calibrate their levels very easy since you can hear much more of the sound. But if you have multiple subwoofers spread out around the room, you won't be able to sense the loudness anywhere else as well as you are in front of one subwoofer.
More subwoofers means greater headroom
Multi-channel home theater systems are composed of several loudspeakers that work together to create a seamless sound field. A left front, center, right front, left rear, right rear, and a subwoofer (the .1 channel) make up the 5.1 channel surround-sound configuration for the home theater. Subwoofers are part of a system’s bass management, which controls the sound pressure level at both the speaker and your ears, and can rattle your windows if set improperly. A system with two subwoofers has a greater headroom, though lower power than a single subwoofer in the same size enclosure.
Greater flexibility with placement
If a sound bar won’t fit where you want it to go, chances are you’ve got room for a subwoofer. Most subwoofers can be placed anywhere in the room. Subwoofers also make it easier to have different placements in different rooms, so you can play sound in a room without sacrificing bass in another room where you want to crank it up a bit.
Disadvantages of 2 or more subwoofers
Harder to find the sweet spot
If you have two subs or more, it is extremely difficult to find a location where they will both provide great bass. Even a small variation in seating position can change the quality of the bass significantly. You can learn more about this in our article about the ‘sweet spot’.
Each subwoofer should be placed at the front of the room where it can get the full effect from the front and rear left and right channels.
Finding the optimum listening position for all your seats takes a lot of time and effort. If you have a particularly large room, it might be almost impossible.
Those who decide to go the route of multiple subwoofer setups are advised to try and listen to their system in several locations and find the one that gives them the best bass response from every seat.
While this approach guarantees the best bass performance, it’s not very practical and not something that most people have the time or effort to do. However, it is possible to get a good approximation of the bass performance by listening to the system in 2 or 3 locations in the room.
Your budget might not stretch
One subwoofer is a considerable investment. Two subwoofers would surely be financially felt. As long as your budget doesn't suffer and you can afford to buy two subwoofers of the same quality, you are probably good to go.
Incorrect placement can have a big impact
Even if you’ve carefully accounted for every other aspect affecting sound quality, your system may still sound like it’s been tuned by a 3-year-old if you find yourself in the unfortunate situation of having a subwoofer placed in the wrong position. This single mistake can have a big impact on a system’s performance, so it’s important to know the guidelines before you install your subwoofer.
The right place for a subwoofer is anywhere where the bass you’re hearing is clear, tight, and accurate because the subwoofer’s location is one of the most important factors in improving the performance of your home theater or stereo system. One note — even if your subwoofer sounds better in a different position, you may need to keep it in the wrong place to get the best performance out of your other speakers. And in that case, you're not alone — we're with you, and so are most of our customers.
It’s not going to matter whether you choose two subwoofers or one with a different brand. That is for the most part going to come down to your budget and the brand you think is going to last longer. If you’re going to run it active from your speaker or amplifier, then it would simply be about what amplifier you prefer. But if you plan to simply connect an external processor to your system, then I would say go ahead and choose the one you prefer. It really won’t make a difference.
Hopefully, this article has put this issue in perspective. And if you’re really serious about getting the best out of your system, then you can always upgrade your system speakers later on down the track.