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Why You Need A Subwoofer

September 2, 2014 | Comments

The sense of impending doom was palpable.

You knew the fearsome Tyrannosaurus rex was near. You could hear - no, feel - the thunderous footsteps in the jungle as the creature approached. Boom. Booom. Boooom.

The floor moved with each step as Dr. Grant and the group of scientists braced themselves for the encounter.

If you haven't already guessed it, the scene we're referring to is from Jurassic Park. It's one of those cinematic moments you don't forget - even 20 years later - and one that wouldn't be nearly as terrifying without a good subwoofer, whether you're experiencing the action at home or at the local Cineplex (in which case there would be multiple good subwoofers).

Creating a credible theater experience at home requires careful design and installation, with special attention paid to the screen and the sound system. Ideally, you want a high-definition TV or projection system that delivers vivid, lifelike images that pull you into the action - the bigger the better.

But equally important is the sound, which conveys emotion and that sense of "being there," whether "there" is relaxing under the stars on a tranquil summer evening with crickets chirping in the background or cowering behind a palm tree in a dinosaur-infested jungle.

Edge-Of-Your-Seat Sound

To create an enveloping "surround sound" effect, movie soundtracks are divided up into channels with a typical home theater setup having 5.1 channels reproduced by front left, center, and right speakers, two surround speakers on the side or back walls, and the mighty subwoofer that is the topic of this article.

Up front, the left and right channels convey music and sound effects while the center channel handles mostly dialogue. The rearward surround channels complete the sonic picture, with sound effects that provide directionality (Pterodactyls flying overhead) and ambience that creates a sense of space (the expanse of a tropical forest).

The ".1" channel handles only low frequencies, feeding deep (often powerful) bass to the subwoofer (or subwoofers if you have a large room or an appetite for big bass). It's the conduit that adds depth to a movie soundtrack, giving music presence and, when necessary, invoking terror (Terminator, Die Hard, Transformers…pick your action/adventure series).

The deep bass conveyed by the subwoofer actually comes from two sources: bass that's split off from the main channels (to ease the burden on the main speakers) and low-frequency effects (LFE) information added by sound engineers to create emotionally charged sounds, like the rumble of thunder or an explosion. In movie soundtrack production, the LFE channel is optional but almost always used to reproduce larger-than-life sound effects, like T. rex's pounding footsteps.

Getting good, balanced bass and realistic-sounding low-frequency bombast requires proper placement of the subwoofer(s), proper setup of the system's bass-management controls, and, in some cases, acoustical treatments to the room itself. That's why it pays to consult a home theater specialist if your goal is a home theater experience that rivals what you get in the best cinemas.

So the next time you pop in a Blu-ray disc or visit the local movie theater for an evening of action and adventure, you can thank the subwoofer for turning an ordinary experience into an extraordinary one.

To learn more about subwoofer setup and home theater options in general, consult a CEDIA professional. Click here for a list of CEDIA-member Electronic Systems Integration companies in your area.