Speakers – How They Work and What They Do

Speakers – How They Work and What They Do

After the response from the power capacitor article, there have been many requests for an article on speakers and which ones are the best to have as well as how to choose the speakers for your ideal car audio system. 15 inch speaker box  So if you want to know the basics behind creating a car audio system so great that it almost feels as if Linkin Park are rocking out in your back seats while Jay Z is sitting next to you telling you about his 99 problems, then you’ll want to give this a read… just my 2 cents…


Speakers (drivers) are a vital part of car audio systems. They take charge of reproducing the sound from electrical to audible. They work by vibrating the air around the speaker when an electrical current is passed through them. This is why it is important to choose the best speakers that your budget will allow. This will give you end impression that you would feel that you were in a live concert hall; with the artist next to you actually singing live!

Types of speaker

There are usually four types of speaker used in car audio set ups. For the low end of the sound spectrum, subwoofers and mid-bass drivers are used; the middle of the sound spectrum is taken care of by the mid-range drivers while the high end is reproduced by tweeters. There are also speakers such as 6×9’s that are able to produce a broader spectrum of sound than a standard midrange driver on its own for example and also the design of the speaker varies depending on the intended use.


Tweeters are used to play the high end of the sound spectrum. Due to the nature of the speaker, either an inline capacitor or a crossover is used to filter the sound out to ensure that only the frequencies that the tweeter is designed to play are sent to the tweeter. The crossover may also aid in reducing damage to the tweeter, as well as increasing efficiency of the speaker. With my car, I chose to install a separate pair of JBL GTO-18T tweeters that are running directly of the head unit. This is purely to aid my pursuit to produce a special sound in the car as opposed to just sound coming directly from the speakers.

Midrange speaker

The midrange is a vital part of a car audio system. It is in theory possible to run a car audio system solely of midrange speakers however for someone wishing to recreate sound at a high level, it is unheard of. The midrange speakers come in a variety of sizes to fit the different door panels. Unlike subwoofers for example, midrange speakers are able to run directly off the head unit however it is common to see that if the head unit is turned too high, then distortion can be heard (clipping). This is why many people choose to add an amplifier to amplify the signal sent to the midrange speakers so that at high volumes, a cleaner signal is being sent to the speakers. Again some will choose to use a crossover system to limit certain frequencies to be reproduced by the midrange speaker. There are two types of midrange speaker, component and coaxial. The difference between component and coaxial is design. With a pair of component speakers, the tweeter is separate to the main driver whereas with a coaxial speaker, the design is of an all-in-one nature. The difference is in the type of sound produced. As coaxial speakers are all in one, the sound comes from one location, however with component speakers, the tweeter is separate thus it is able to achieve a more spatial sound. Due to the benefits offered with a set of component speakers, in my car, I have chosen to use one pair of JBL component speakers to act as the ‘front speakers’ as well as a pair of JBL coaxial speakers as ‘rear speakers’ even though they both have been installed in the door. The reason for this is that my car, out of the factory only has 2 speakers, one in each door. This left me with the problem of how I was going to achieve a spatial sound. To go about this, ideally I needed to have another pair of speakers acting as the ‘rear’ speakers. This is why I had chosen to use a set of coaxial speakers for the rear speakers and a set of component speakers for the ‘front’ speakers. The idea of this would be to achieve a surround sound from the system while inside the car, and given the conditions I had to work with, I’m pretty happy with the turnout of the overall system.

Mid bass

Mid bass drivers produce frequencies between the subwoofer and the midrange speakers. Some people argue that they are not a vital part of a system while others swear by them. For some simple systems, the mid bass driver can be a vital tool if someone is aiming to achieve clarity over loudness, as again, it would be separating the sound spectrum even more to each of the components so that fidelity will be increased. For my project, I had decided against the use of mid bass drivers purely dude to space confinements of my project car.


Subwoofers come in a variety of sizes usually 8, 10, 12, 15 and 18 inches. They are used to produce the low frequencies. Almost all subwoofers are amplified due to their demand for high power; however a few head units and subwoofers from pioneer are able to work together without the use of an amplifier. Some subwoofers require an enclosure, this may be a sealed or vented enclosure with some subwoofers being free-to-air, i.e. they will work without the use of an enclosure, and however these subwoofers on average require more power than a subwoofer of equivalent sound output that requires the use of an enclosure. Free-to-air subs have also been commented on by many people who say that they find that type of bass that is produced is not of the same standard or quality even though they are rated at the same power. There are also active bass boxes where the amp, subwoofer and the enclosure are all built into one unit however they, on average tend to have a lower power output than say a separate sub/amp combination. This is why many people will choose an enclosure type subwoofer. The presence of a port will adapt the type of bass produced. With a port, many people find that there is more bass produced (as the subwoofer is moving the air through a tuned port, however there is less definition in terms of the sound. With a sealed enclosure however, the bass produced can be described as more of a tighter sounding bass as the air is moved inside the box, however the use of a sealed enclosure will also put more strain on the subwoofer, due to the pressure levels built up inside of the enclosure.

While doing some research for my enclosure, I found that the size of the enclosure makes a massive difference. After choosing the Kicker L7, I had two options for my enclosure, to either use a sealed box that would be very small (the benefit would also be to save space) or if I wanted to use a ported box, then the size would be much larger and the effect of the bass would be different as greater pressure levels could be built up inside the car with a slot ported box, which is why I chose the ported box.

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