Subwoofer Enclosures

In car audio parlance, speaking of subwoofer enclosures is never a stroll in the park. One should see subwoofer enclosures as something that ultimately decides the skill you have as an installer for car audio.

One of the ABCs of installing subwoofer enclosures is the understanding of how a ‘car audio cabin gain’ works. Let’s start with a first question? Have you ever wondered why a small cabin compartment seem to blast so much sound compared to a larger own, like a Ford Expedition? The reason is because of space, the very same concept exist when comparing a home system to a car audio. Bass notes have long, low waves that build up every beat of a music. Try envisioning a momentous bass thump, lasting say 0.05 seconds. If every second a bass thump is produced, a small space gets filled with the thump more quickly. You can calculate the length a bass sound wave by dividing the constant speed of sound (1000ft/sec) by the frequency, thus acquiring the product but since we’re talking subwoofer boxes and as the calculations may very well take another article, let’s bottom-line the fact: due to the smaller space-volume of vehicles (normally), the bass won’t have enough time to disperse as fast as it would on wider volume spaces.

Saying this of course won’t mean, too that smaller vehicles would out thump larger vehicles. The more space you have for additional equipment, the larger air you move with each thump, and the more bass is felt.

One minor aspect of car audio cabin gain is the horn effect. Cars with a hatchback, when the rear is installed with a speaker (mid pass or subwoofer), the inclined face of the hatchback will serve as a horn, a triangular area that creates an unintentional pressure to the sound thus it produces sounds louder in effect. Though you might not notice it, the car audio horn effect is indeed a working technique. Use it to your advantage. Normally, OEM speakers when you buy a brand new car are installed at the back of the rear seat, thus creating this phenomenon. But you can have any speaker you want installed there. For me, I would go for mid band speakers there, subwoofers on the trunk and tweeters near the back seat panels.

Understanding Subwoofer Enclosures

There are several kinds of subwoofer enclosures; all of them present their own strengths and weaknesses. The easiest to install is the Infinite Type, also called free air system. What it really is just a component subwoofer mounted on a panel. This panel’s back may or may not be covered. The only advantage of these subwoofer enclosures is that it is very simple to setup, anyone can do this by himself in a matter of hours. The disadvantages, and there are many, is the larger power requirement for the subwoofer, and the complete unfeasibility of separating to signals from two different subwoofers strung together.

Another is the most common, the simplest, for everything it requires; the produced sound can be very gorgeous. It is the Sealed Enclosure, a completely sealed box with only the speaker cones showing. Vented Enclosures are outcrops to the original design; with the only difference is the presence of a “vent”. This is one of the most popular designs for subwoofer enclosures; due to the fact it gives all the benefits of the sealed enclosure yet minimize the negating aspects. The advantages are the afforded increased efficiency (though only a fraction when compared to sealed enclosure) and a lower frequency requirement above the port tuning frequency.

There are more subwoofer enclosure types that feature benefits not found on yet others. Be sure to know the tradeoff of each enclosure design, so that you can compensate the loss to other aspects as well.