Unless you have a late-model vehicle that shipped with premium sound, there's a good chance that your car or truck is begging for a serious overhaul in the speaker department. Whether your speakers are starting to wear out or they were never that great to begin with, there are plenty of reasons to replace factory car speakers with aftermarket ones.
Upgrading Car Speakers: Price vs. Quality
The main argument against replacing speakers is cost, but installing direct replacement aftermarket speakers can be a great way to bump up your sound quality without breaking the bank. Although it can get expensive, if you upgrade to component speakers, you'll enjoy an improvement in sound quality.
If you are looking at an overall upgrade to your car audio system, your factory 4x6 speaker should be one of the first components to hit the chopping block. It's unlikely that your original speakers are up to the task of working with a premium head unit and amp, so leaving them in place will hamstring your dream system.
In that case, you may want to stay away from direct replacement speakers. If you want to get the most out of your new custom car stereo system, your best bet is to replace the factory speakers with high-quality component speakers—and throw in at least one subwoofer.
Although aftermarket speakers usually yield improved quality over a stock system, component speakers are hard to beat.
Upgrading Factory Speakers on a Budget
If you want to squeeze the best possible sound out of your factory sound system and you don't have an enormous budget, the speakers are a great place to start. Most OEM systems use full-range speakers, which is a fancy way of saying that each speaker has a single driver that's capable of reproducing all or most of the audio spectrum.
The advantage is that full-range speakers are comparatively cheap and take up less space than individual component speakers. However, you may end up paying elsewhere with muddier sound. If you replace car speakers that fall into the full-range category with two-way or three-way speakers that have multiple drivers or individual component speakers, the difference in sound quality will be remarkable.
Premium aftermarket speakers also tend to be engineered better and constructed from higher quality materials than factory speakers. Most factory speakers use surrounds that are made out of foam and paper, which deteriorate over time. When speaker surrounds wear out, the sound quality deteriorates. High-quality aftermarket speakers tend to use rubber surrounds that last longer and facilitate the delivery of higher-quality bass.
The cones in aftermarket units are often made from denser materials as well. That's another reason why a high-quality aftermarket speaker typically has better bass reproduction than a similarly sized factory speaker. So if you don't have the money to spend on high-quality, two- or three-way speakers, replacing old factory speakers with new units will typically result in better sound.
Building a Car Audio System From the Ground Up
Replacing your factory speakers won't make up for a low-powered head unit or amp, which is why many audiophiles choose to design a new system from scratch. In that case, it's vital to replace low-quality factory speakers with superior aftermarket units.
In the same way that two- and three-way speakers provide better sound than full-range speakers, component speakers are even better at reproducing higher and lower frequencies. Since you can handpick a head unit and amp to match your speaker configuration, this type of setup allows you to blow other car audio systems away.
Replacing factory car speakers with real woofers and tweeters is more complicated than just dropping in some two- or three-way speakers, but it allows you to design a soundstage that's perfect for your car.
Will New Car Speakers Fit?
One of the biggest challenges with replacing factory car speakers with component speakers is that you often run into space and mounting problems. For example, if you replace four coaxial speakers with some combination of left, right, and rear-channel woofer, tweeter, and mid-range component speakers, you won't be able to drop the new ones into the enclosures designed for the factory units.
Even when you go with aftermarket coaxial speakers, space can be a problem. You may be able to get away with buying replacement speakers with the same measurements, but you can still run into some trouble.
For instance, 6-inch-by-9-inch is a common speaker size; it refers to the length and width of the speaker. However, different 6-by-9 speakers have different depths, so some units may not fit in some applications. Some units also incur a significant amount of tweeter protrusion beyond the basic mounting height, which is why it's important to consult a fit guide before you upgrade your car speakers.