[April 03, 2006]

Gadget: Subwoofer, the speaker that can shake you up

(The Jakarta Post Via Thomson Dialog NewsEdge)from THE JAKARTA POST -- WEDNESDAY, MARCH 29, 2006 -- PAGE 15 The subwoofer has become an indispensable part of the home theater system. This is the device that produces thunderous sounds at cinemas, particularly during the screening of horror or action movies that are plentiful with roaring sound effects. Although subwoofers used in home theater systems are not as loud as those used in cinemas, the sounds produced by the former is powerful enough to shake the panes of your windows or even to annoy your neighbors

So crucial is the role of a subwoofer in a home theater system that people say that without it you don't have a real home theater

A subwoofer is an individual speaker unit that is specialized in low frequency sounds. The sound frequency audible to humans ranges between 20 and 20,000 hertz. A subwoofer is responsible to produce the lowest end of the frequency range in a home theater system

Typically, a good sub is equipped with a 100-hz frequency "crossover". This device functions to filter sounds so that those with a frequency of lower than 100 hz go to the subwoofer and those with higher frequency stay at front, center or rear speakers. Bear in mind that a 5.1-channel home theater system has one center speaker, two front speakers and two rear (surround) speakers. The "1" in the 5.1-channel system denotes subwoofer

There are two types of subwoofer: "passive" and "powered"

Passive subwoofers are powered by an external amplifier, in the same fashion as other speakers in your system. The important consideration here is that since extreme bass needs more power to reproduce low frequency sounds, your amplifier or receiver needs to be able to put out enough power to sustain bass effects in the subwoofer without draining the amp

Powered subwoofers are equipped with built-in amplifier. This type is created to solve the problem of inadequate power or other characteristics that may be lacking in the amplifier or the receiver

Since the built-in amplifier is set to match the characteristics of the subwoofer, this type of subwoofer rarely produces defect sounds

Most subwoofers feature a single woofer cone that moves back and forth to create low-frequency sound waves. The woofer cone is usually mounted either on the bottom of the subwoofer cabinet (this type is called "down-firing subwoofer") or on one of the sides of the cabinet ("front-firing subwoofer"). Front-firing subs radiate sounds to the front or sideward, while down-firing subwoofers radiate the sounds downward, to the floor. Neither method is intrinsically better as deep- bass frequencies produced by subwoofers are "non-directional" (meaning it's difficult for us to pinpoint where the bass sound comes from) given that the frequencies are at or below our hearing threshold. That is why we can only sense that an earthquake seems to be all around us, rather than coming from a particular direction

When you buy a home theater in box (HTiB), it is one of the components included in the package. But, you can also buy the device individually, if you want to build a discrete home theater system. There are various types of subwoofers on the local market. Among the types now popular among high-end consumers here are AAA (American Acoustic Development) 10, Mordaunt-Short 907W and PSB Subsonic 5i, which cost between Rp 3.5 million and Rp 3.7 million each

One of the first things you need to consider when shopping for a subwoofer is how much power you need. If you have a large room, then you should look for a sub with more watts in the built-in amp. Plus, as a general rule, the larger the driver, the deeper the bass -- so go for a sub with a big 12 inch or 15 inch woofer cone (or a multi-woofer sub) for serious bass response

Given that subwoofers reproduce "non-directional" frequencies, the devices can be placed anywhere in the room. However, optimum results depend on room size, floor type, furnishings and wall construction

Typically, best placement for a subwoofer is in the front of the room, just to the left or right of the main speakers

Copyright 2006 The Jakarta Post

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