Going Low with Subwoofers

In This Chapter

► Getting low bass in a vehicle 

► Choosing prefab subwoofer box 

► Understanding enclosure types

► Wiring a subwoofer

► Building a subwoofer enclosure

When most people think of subwoofers, they likely think of the boom cars that pass by pounding out bass and rattling windows. And while that’s a significant if often unpleasant part of the car audio experience, there’s much more to subwoofers than just annoying an entire neighborhood.

In this chapter, I cover all of the options for getting bass into a vehicle. I’ll explain readymade options such as prefabricated subwoofer boxes, including some that have amplifiers built in. I also detail what’s entailed with buying a raw or stand-alone subwoofer and matching it with the right enclosure. And speaking of enclosures, I guide you through their myriad variations — and discuss the advantages and disadvantages of each — as well as demystify the often confusing array of subwoofer wiring schemes. Finally, I teach you how to build your own simple sealed subwoofer enclosure.

Going Low with Subwoofers

Choosing a Subwoofer

Low bass is an integral part of high-fidelity music reproduction. Think of the last time you heard great live music. Whether it was an orchestral performance or a rock concert, chances are you felt the impact of the bass drum and other low-frequency instruments as much as you heard them. Bass, whether produced live by instruments or reproduced by a high-fidelity sound system, has a visceral quality. That’s what a subwoofer adds to a car audio system. 

In addition to low bass’s tangible impact, instruments such as a bass drum,bass guitar, and synthesizer all create sounds as low 30 Hz or more. If you only have midrange speakers that can only effectively play as low as, say, 75 Hz, you’re missing out on an important part of your tunes. (Some would argue the most important part.) So the only way to go low is to add a subwoofer to your car audio system. But you’ll be faced with many and often confusing options. But don’t fear. I’m here to help you get the bass you want and need.

Shopping for a subwoofer can be one of the most daunting tasks of putting together a high-performance car audio system. First, there are so many choices: everything from prefabricated subwoofer boxes to raw or stand¬alone subwoofers that require an exact-size enclosure.

But that’s also the good news. With so many options to choose from, you’re bound to find something that works for your budget, vehicle, and musical tastes. You also have to figure out how to power your subwoofer system:

Subs require more juice than any other speaker. This can be done with a sep¬arate mono or single-channel subwoofer amp, a dedicated mono channel of a multichannel amplifier, or by bridging or combining two channels of a stereo amplifier into a single mono channel.

Why is a box needed for bass? I go into this later in the chapter, in the section “Going with a raw sub,” if you want to skip ahead. But suffice to say that, as with any speaker, the output from the front of the speaker caused by the cone moving forward has to be isolated from the output from the back of the speaker caused by the cone moving backwards. Otherwise, the sound waves caused by the movement of the cone, which are mirror opposites sonically speaking, effectively cancel one another out.

But with subwoofers, it’s a bit more complex than that, which I’ll also go into in more detail later in the chapter. Subwoofers are designed to work in certain sizes and certain types of enclosures. Therefore it’s of paramount importance that the subwoofer and enclosure are properly matched. That’s why the sim¬plest approach, if you’re just starting out, can be to simply buy a prefab box either with or without a subwoofer.

Prefab bass

The easiest route to good bass is to go with a prefabricated box (as shown in Figure 16-1). You buy a box with a sub already mounted in it, or you can buy a subwoofer and a box separately. Many car audio manufacturers sell pre- loaded sub boxes, and some offer unloaded boxes that are designed for one of their subwoofers. Other companies offer universal boxes that can fit a variety of subwoofers. 

Matching a subwoofer to the right size enclosure is crucial. Placing a subwoofer in too small or too large a box will seriously degrade its performance because the subwoofer won’t perform optimally. It would be like dropping a 500-horsepower engine into an economy car: The transmission and other parts of the car aren’t designed to handle the respective engine.

Simply buying a sub and box together as one unit takes the guesswork out of it, and the manufacturer will have undoubtedly matched the sub precisely to the box. Even if you do match a raw sub to a universal box, you still have to mount the sub inside it. For novices, buying a box with the sub already mounted inside is the best way to go.

After you’ve decided to go the prefab route, you can narrow down the type of enclosure that’s best for you. You should consider the kind of music you listen to, what your goals are for the system, and how much power you’ll need to drive it. Do you want to pound the pavement, or do you just want good bass to punch up your music? Bassheads will want to go with the largest number and size of subwoofer possible to create the bumpin’ sound they crave. Those looking more for sound quality can get by with smaller subwoofers and fewer of them. For example, a high-quality box with a single 10-inch subwoofer works for most people who only want to add some low-end to their tunes.

Prefab subwoofer boxes come in a large variety of sizes, shapes, and configurations. You can get one that will completely fill up the hatch of your Honda Accord or will fit neatly in one corner. Prefab sub boxes come in shapes ranging from squares to rectangles to wedges to tubes, and they come with your choice of one, two, or three or more subwoofers. Before buying a prefab box, start by determining how much space you have in your vehicle to accommodate it.