Subwoofers are speakers designed to produce only low frequencies. The name comes from the combination of subsonic and woofer. Subsonic frequencies are frequencies that can not be heard because they are actually lower than the ability of our ears to hear them. Subwoofers produce both audible and non-audible signals.

People buy subwoofers because they believe they aren't getting the proper amount of bass they should from their system. Often times, buying a subwoofer only adds distortion and does little to add any real bass energy. There are many reasons why you might not be getting bass. Many loudspeakers that are rated at down to 45 Hz actually have very little output at this frequency. A loudspeaker that produces energy below 50 Hz isn't going to sound weak or thin if it is properly driven.

Low frequency wavelengths are much longer than higher frequency wavelengths. Most rooms can not accommodate a full wave of 30 Hz. This is why you can sometimes hear bass coming from the floor below but not in the same room. In many cases, the low frequency wave reflects against the wall and produces an out of phase wave that creates standing waves that cancel each other out. Before you spend money on a subwoofer, try to determine if you really need a subwoofer or should you move your speakers around or do you simply need better amplification.

Subwoofers come in two varieties--powered (active) and non-powered (passive). Active subwoofers have their own amplifiers. Many loudspeakers today have integrated passive subwoofers. The problem with passive subwoofers is that large coils are required. These large coils become so resistive that they make the entire system inefficient. The resistance takes away the amps dampening factor. It also creates bass that is slow and uncontrolled. It is very difficult to produce a passive subwoofer that crosses over lower than 100 hz for this very reason. Some of the world's most expensive loudspeakers use passive crossovers. They do this because it's cheaper--not because it is better.

The advent of home theater has made subwoofers very popular. Most of the subwoofers sold separately are active. Most of them use amplifiers made in Taiwan and China that are rated anywhere from 75 to 150 watts. Unlike the amplifiers you use for your full range loudspeakers, there are no standards for how you rate a subwoofer amplifier. Most of these amps would be a fraction of their rating if they had to comply with FCC requirements. The nOrh subwoofer amplifier is rated at 150 watts from 20 to 20,000 Hz. The amplifier is designed as a high fidelity amplifier with an active crossover. It is like buying a high-end amplifier to drive a single woofer. In fact, the nOrh subwoofer amplifier is essentially the same as a bridged Multiamp.

Adding a subwoofer should not shake the walls. It should not vibrate your furniture. It should simply add depth and intensity to the music. When there are sections with deep bass, the bass should create shockwaves that you feel but don't hear. The sounds you hear of things rattling in your house is not from the bass. It is from the resonances (distortions) that cheap subwoofer amplifiers put out.

The term subwoofer is frequently misused. There are many audio systems that use a single passive bass module and refer to it as a subwoofer. If the unit produces directional information, it is not a subwoofer. Bass information is non-directional.

Some newer systems suffer from a syndrome I call "tinkle-tinkle-boom -boom". This means that the system produces high frequencies through two small satellite speakers and some boom through a single bass unit. These systems are rarely musical, and seldom handle much power. The advantage of these systems is that they are less expensive to produce than a system that has woofers in one cabinet.

For most musical applications, a subwoofer will only add a slight amount of additional information. There is very little musical information below 40 Hz. Only the piano, oboe and a few other instruments produce music this low. Furthermore, it takes a very large room for a low bass frequency because of the length of low frequency sound waves. If a subwoofer is properly used, the music will have more authority and the music will sound more natural. If the subwoofer produces enough energy to be obvious, during music, it is being used improperly. For an article on proper use of a subwoofer, see the following URL.

NOTE: One of my favorite websites for audio is Decware. It is as opinionated as this one. The author is on the same mission as nOrh (audio should be better and it should cost less)--good luck Steve.

If subwoofers were medicine, I would say they were frequently mis-prescribed. This is not to say that there is not a good reason to buy a subwoofer. Subwoofers are very useful additions to audio and video systems if they are properly used. Most people that buy subwoofers are buying them for the wrong reason. They buy them because their system seems to lack punch. Simply adding a subwoofer will not necessarily improve the sound.

If your loudspeaker advertises itself as being "full range" (45 Hz to 20,000 Hz), you should not notice a deficiency in the bass response when producing music. Chances are that the lack of bass is due to the amplifier not being able to produce deep bass rather than the problem being the loudspeakers.

We have done many experiments with various amplifiers to test their impact on bass. Our observation is that the amplifier has a profound impact on the quality and quantity of bass. Many amplifiers simply can not produce good bass. Bass requires a great deal of current to flow to the woofer quickly. Most amplifiers simply lack this capability.

If you buy either the nOrh 6.5 or nOrh 7.0 for audio, it is unlikely you will ever require a subwoofer. A high quality subwoofer will offer a subtle increase in bass energy for some music. However, the bass output from the nOrh 7.0 and nOrh 6.5 will be strong and authoritative most of the time. Adding a good subwoofer will improve the dynamics and impact of the system.

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