It’s one of the hallmarks of a great home theater; great bass. Everyone wants the kind of bass you can feel, that hits you against the seat when necessary and makes your pants legs flap. What a lot of people get is a weak and anemic bass or a booming bass that sounds like mud. In many cases, you will have very good bass in one seat and little to no bass in other seats. Sometimes you try to turn up the subwoofer level to compensate for these shortcomings. Usually that makes the bass even more bloated and booming. Sometimes it causes your subwoofer to run out of gas and your amp clips, the cone to bottom out, or both.
What can you do? How can you get that great bass you’re looking for, not just in a seat, but anywhere in your home theater system? How can you get great sounding bass for action movies and music too? Is it that $ 800.00 subwoofer that has a total loss?
The good news is, you can get great bass from your home theater system, and probably every seat too! Usually it comes down to two things; selection and placement of the subwoofer. Your submarine must be sized appropriately for its intended function. If your home theater system is larger, say 27 ‘x 17’ x 10 ‘, especially if it is a multipurpose room that is open to the rest of the house on one or more sides, you will need a larger subwoofer than if its the room is small. It all comes down to basic physics. To make bass you need to move the air in the room. To do a lot of bass you need to move a lot of air. If your room is larger, your sub must move more air to get the same effect as in a smaller room.
In the old days, when comparing subwoofers from good manufacturers, you could only look at the size of the subwoofer cone and the power of your amplifier. This will give you a general idea of the result. Most subwoofers used similar designs, either a bass reflex box (ported) or acoustic suspension (sealed). Most of the quality subwoofer drivers had somewhat similar excursion specifications. Now, with the advent of high-power digital amplification and super long-throw drivers, things are a bit more difficult.
There are 10 “subwoofers on the market that move as much air as some of the older 15” units. This is because the cone has a very large peak-to-peak excursion specification. It is important that the controller is designed correctly so that it remains in its linear range when moving that far. This is probably nothing you need to worry about if you are buying a subwoofer from a quality manufacturer. That’s what your design engineers are for.
The main advantage of this is that using the high-power digital amplifiers, a long-throw driver can get very good performance in an undersized box. A small box has many more placement options and does not interfere as much with the aesthetics of the room. Two of the notable companies that produce these types of very small subwoofers are Sunfire and Velodyne. Most manufacturers will have recommendations on which of their subwoofers to use in a given room size.
Now the most important key to getting great bass from your home theater system; use multiple subwoofers. According to some of the latest research, the way various subwoofers interact with the room is the single most important factor in getting great bass from every seat in your home theater system. One of the biggest problems in small room acoustics is caused by standing waves. These are created when the wavelengths (or ½ or ¼ wavelengths) of certain frequencies coincide with one or more dimensions of the room.
For example, a 49Hz tone has a wavelength of almost exactly 23 feet. Standing waves cause certain frequencies to boost and cancel in different places in the room. These troublesome frequencies are known as room modes. The effect of standing waves is to have areas of the room where the bass is very booming and others where there is no bass at all. An equalizer will do nothing to fix these problems and may even make them worse!
You should use two or four subwoofers. There is not much benefit to using more than four. When using two subwoofers, they should be placed on the floor, in the front corners of the room. For even better bass and smoother frequency response throughout your home theater, use four subwoofers. These should be located on the floor, at the midpoints of each wall.
You will still have some peaks, but you can fix them with a good parametric EQ. You can use a graphic equalizer, but the equalizer should have a resolution better than 1/3 octave. This will help ensure that you can target the precise peak frequencies. However, if you can, use a parametric file.
Using the correct subwoofers for your room and using multiple subwoofers with a good EQ will help you get that spectacular bass that your home theater system lacked.