There is no component more important to the sonic performance of your vehicle’s sound system than the car audio speakers you chose to install. You may own the best radio and amplifier in the world, but without great speakers, none of that great sound can get to your ears. Let’s look at why speakers are so important and a few suggestions on how to pick the best ones for your system.

Different Designs of Car Audio Speakers

Every car audio speaker is engineered to operate well within a specific range of frequencies. As a generalization, subwoofers are best at playing those frequencies below 80 Hz. Most midrange speakers can play from 80 Hz to 4 kHz, and tweeters typically play from 4 kHz and up. The size and weight of the speaker cone or diaphragm and the stiffness of the speaker’s suspension components (the spider and the surround) all affect the frequency response of the speaker. We need different-sized speakers to cover the entire audible range of audio.

For the speakers in your vehicle, you have two design choices – component or coaxial speakers. In a component speaker set, the midrange and tweeters are separate pieces. The midrange is often installed in the factory door or dash speaker location, while the tweeter is mounted high in the door, on the dash or in the A-pillars. This higher location helps make the sound appear to come from in front of you rather than from down by your legs. Coaxial car audio speakers still have two separate drivers. The tweeter is physically mounted to the midrange – typically, on a post that extends up through the center of the speaker. Coaxial speakers are easier to install, because there are only two pieces, not four. Both designs can sound very good, but typically, the best of the best speakers are designed as components.

A common trait among high-quality car audio speakers is high-quality passive crossover networks. Every tweeter needs some method of limiting what frequencies are being sent to it. In better systems, the output of the midrange that would normally overlap where the tweeter was playing is also filtered out. Passive crossovers can include tweeter level controls to help provide some basic system tuning.

Listen To This

Listening to speakers has been described as “personal preference” for decades. That being said, a speaker that is very accurate and free from distortion will always stand out from a speaker that has design issues. The best way to audition speakers is in a vehicle. Some companies put extra effort into the design of their speaker systems to make them sound better in a vehicle as compared to on a display board. Retail display boards have the benefit of letting you quickly compare the performance of several different models. Listening to both a demo vehicle and display can be the best solution for helping you pick a great set of speakers.

When you go to listen to speakers, bring your favorite music. It should be something that you have listened to many times on as many different sources as possible. Pick out and listen to different portions of the performance one at a time. If you are comparing speakers on a display, you can switch back and forth as you listen to different pieces of the performance.

Listen for vocals to sound natural. If there is too much high-frequency information, then S, T and P sounds will be over-emphasized. If there is an unwanted resonance in the midbass region (a very common problem with lower-quality speakers), then M and B sounds may be pronounced and sound unnatural. Some speakers sound nasally, some sound harsh. Either can be a sign of a distortion caused by the speaker design. Keep looking if you hear that.

Listen to high-frequency sounds like the ring of a cymbal or high-hat. It should have clarity and detail. Listen for the speed of transients – drums are a great test of a speaker’s ability to reproduce a wide range of frequencies while demonstrating smooth frequency response and lack of distortion. Drums should sound tight and controlled, with great definition.

Size Matters

When it comes to reproducing music, the size of your speakers has a dramatic effect on what you hear. A speaker with more area can move more air for a given amount of power – we refer to this as efficiency. The design of the speaker’s voice coil and the magnet structure also affects efficiency. In most cases, a larger speaker also produces more bass than a small speaker. This has to do with the weight of the speaker cone and the flexibility of the speaker’s suspension components.

Finally, how far the speaker cone can move will determine how loud the speaker can play. Don’t forget; you need amplifier power to move the speaker cone – don’t skimp on power.

Choosing Car Audio Speakers By The Numbers

One thing that an experienced car audio retailer rarely talks about is power handling. While this is important if you are looking for sheer system volume, power handling is in no way a quantifier of the quality of a speaker. There are speakers rated at 50 watts that sound exponentially better than speakers rated at 200 watts. Just as with amplifiers, manufacturers play many games when it comes to speaker power ratings. The only number that matters is the continuous power handling, sometimes referred to as RMS power handling. If you see a speaker with a CEA-2031 Power Rating, that is the best number to use. Max and peak power numbers start to make assumptions about the energy content of music, and it’s best to avoid assumptions. But don’t forget, power handling does not relate to sound quality in any way.

Drop in at your local specialist and have a listen to a few different car audio speakers in the appropriate size for your application and your price range. It may even help to make some notes as you listen. Your installer can offer suggestions like new wiring and sound deadening that can further improve the performance of your speakers once they are installed in your car. Don’t be afraid to ask questions and most importantly – have fun listening to your music! That’s what a great car audio system is all about!

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.

For decades, there has been discussion after discussion about which of the different subwoofer enclosures are “the best” and why. Let’s take a look at why we need a subwoofer enclosure at all, and how the three popular styles – sealed, vented and bandpass – differ in their design and performance.

Back-Wave Management

If you were to hook any speaker up to an amplifier, hold it in your hand and play music into it, you would find that you don’t hear any bass. That is because the sound coming from the front of the speaker cancels out the sound coming from the back. We need a way to keep the sound coming from the back of the speaker cone from interfering with the sound coming from the front. If you were to cut a hole in the middle of a large, flat piece of wood and mount the speaker in it, you would hear a lot more bass. In fact, until the half-wavelength of the bass frequencies becomes longer than the dimensions of the piece of wood, you will get really good, solid bass. If we put a speaker in an airtight enclosure, none of the sound coming from the back interferes with the sound coming from the front.

Power Handling

The ability of a speaker to use the power produced by an amplifier is limited by two criteria – how far the speaker cone can move and how much heat the voice coil of the speaker can handle. Thermal power-handling limitations are based primarily on the design of a speaker – the size of the voice coil, how airflow is managed around the voice coil and the proximity of the stationary components of the motor assembly to the voice coil are the key contributing factors. The excursion-limited constraints are also part of the speaker’s design – how long the voice coil winding is, how tall the top plate is and how much suspension travel is available are the key factors.

Excursion

When it comes to reproducing bass, a speaker has to move four times as far each time the input frequency is halved. For example, a speaker moving 0.125 inches at 100 Hz has to move 0.5 inches to reproduce the same output level at 50 Hz and 2 inches at 20 Hz. You can see that, for the lowest of frequencies, cone excursion limitations are significant – very few speakers can move 2 inches without significant distortion.

When we put a speaker in an enclosure, the combination of the enclosure and the speaker create a high-pass filter. We are effectively decreasing the low-frequency output of the speaker. Why would we want to do this? The benefit of an enclosure is that we can control the motion of the speaker cone. Looking at a simple acoustic suspension (also known as a sealed) enclosure will be the simplest illustration of this explanation.

Compliance

Each and every speaker – from the biggest of subwoofers to the smallest of tweeters – has a springiness to the cone. We call this the compliance. We measure compliance by comparing it to a volume of air with the equivalent springiness. We call this characteristic of the speaker Vas. In general terms, a speaker with a very small Vas specification has a tight suspension, and a speaker with a large Vas has a softer suspension. There is a lot more to it than that, but for the discussion of enclosure features and benefits, that’s all we need to get into for now.

When we put a speaker in an enclosure, we stiffen the suspension. When you push in on the speaker cone, you are pushing against the speaker’s suspension (which wants to center the cone) and you are trying to pressurize the air in the enclosure. When the cone tries to move outward from rest, you are putting the air in the into a vacuum state – it wants to pull the cone back to its resting position. We do sacrifice low-frequency output, but we gain significant power handling and control over the motion of the speaker cone. For the latter, the combination of the air in the enclosure and the speaker suspension helps to stop the speaker cone from moving once an electrical signal starts it in motion.

Think of it like a shock absorber on a vehicle. You can see that having an enclosure is critical.

Acoustic Suspension Subwoofer Enclosures

The simplest of enclosures is called an acoustic suspension or sealed enclosure. In these enclosures, we are putting the speaker into an airtight box. When we put a speaker in an enclosure, the system resonates at a specific frequency that – we call this Fc. Below that frequency, the output is reduced at a rate of -12 dB per octave. If the system has a resonant frequency of 50 Hz, the output will be 12 dB quieter at 25 Hz.

Acoustic suspension enclosures are amongst the smallest of the different enclosures we will discuss. They are also the easiest to construct, and most forgiving regarding calculation error. If you combine the roll-off of the enclosure and speaker system with the increase in efficiency you get from the relatively small air volume of the vehicle interior (often called transfer function or cabin gain), you can get a very flat in-car response with good infrasonic output. Bass from an acoustic suspension enclosure is very tight and controlled, thanks to excellent transient response.

There is a down side. If you are looking for loud bass, then you need a driver that has a lot of excursion capability, and you need a reasonable amount of power to move the speaker cone back and forth to get the level of output you want. There is another drawback that isn’t talked about as much, and that is distortion. As a speaker increases in excursion, the amount of distortion it creates increases. Likewise, distortion increases near the resonant frequency of the speaker. So, what can you do?

Bass Reflex Subwoofer Enclosures

A bass reflex (also known as ported or vented) enclosure uses a vent to increase low-frequency output by making use of the speakers back-wave energy. The vent, often a round tube or sometimes a rectangular slot, has an area and a length. The specific area and length of the vent and their relationship to the total volume of the enclosure cause the column of air in the vent to resonate at a specific frequency when excited by the speaker. We typically tune bass reflex enclosures quite low to emphasize the bottom octave or so of the audible frequency range. They can be tuned higher to increase efficiency for high-SPL applications. There is always a sacrifice, though – when we tune the enclosure higher, we sacrifice low-frequency performance.

Bass reflex enclosures are typically larger than sealed enclosures. There is no hard-and-fast rule to associate with the size relationship, but 25–50% large is common. The trade-off for that extra volume is two-fold – more efficiency in the tuning frequency and more power handling, at some frequencies.

When the subwoofer used in a bass-reflex subwoofer enclosure produces frequencies around the resonant frequency of the vent/enclosure combination, the driver excursion is reduced to almost nothing and all the “work” is done by the vent. Put more succinctly, around the tuning frequency, most of the music is being produced by the vent. The benefit to this is that power-handling problems caused by cone excursion limitations are dramatically increased. Since the cone is barely moving, very high sound pressure levels can be achieved. Around the tuning frequency, power handling is limited by the thermal capabilities of the subwoofer.

As we mentioned earlier, one factor that contributes to loudspeaker distortion is cone excursion. With a bass reflex enclosure, the driver moves significantly less than with an acoustic suspension enclosure design. As long as the vent itself has enough area and a smooth transition at both openings, the distortion produced by a properly designed bass reflex enclosure can be impressively small.

Nothing is free, is it? A factor in deciding to use a bass reflex design is how fast the output decreases below the tuning frequency. Where an acoustic suspension enclosure rolls off at -12 dB per octave, a bass reflex enclosure rolls off at 24 dB per octave. Below the tuning frequency, the vent acts more and more like a hole in the enclosure, offering increasingly less back pressure as frequency decreases. Designing for, and managing, driver excursion is a fundamental part of bass reflex enclosure design.

Bandpass Subwoofer Enclosures

We will quickly touch on bandpass enclosures to wrap up this article. There are several different designs for bandpass enclosures. Some use a sealed enclosure, and some a vented one. Independent of whether the rear chamber is sealed or vented, the output of the subwoofer plays into a vented enclosure. This enclosure acts as a low-pass filter. Why would we want to design a bandpass enclosure?

First and foremost, all of the output of the enclosure is produced by the vent or vents. This allows a creative designer to build an enclosure in the trunk of a vehicle and have the vent opening play through the rear parcel shelf. There have been some amazing bandpass enclosures build in the front storage area of mid- or rear-engine vehicles. The vent allows the bass to enter the interior of the vehicle. Bandpass enclosures can also offer impressive gains in efficiency over acoustic suspension and bass reflex enclosures, but they do so at the sacrifice of bandwidth and enclosure volume.

A bandpass enclosure has two resonant frequencies – one for each of the enclosures. The resultant management of cone excursion can allow a great deal of bass to be produced from limited excursion drivers. While the speaker cone itself does not move a great deal, the amount of work done by the motor assembly is still significant. You are still putting power into the speaker, and work is being done. Because the front chamber of the enclosure acts as a filter, it can also be very difficult to hear when the speaker is distorting.

Regarding the complexity of design, and forgiveness of construction error, bandpass enclosures are the most complicated to execute perfectly. Unlike an acoustic suspension or bass-reflex design, bandpass enclosure designs must be tailored exactly to the speaker they are being used with. Never trust the concept of a “generic” bandpass enclosure.

Lastly, because a bandpass enclosure includes an acoustic low-pass filter, it has to be used with good-quality, appropriately sized midbass drivers. If not, the bass can sound lost or disconnected relative to the rest of the music.

For More Details On Subwoofer Enclosures, Visit Your Local Specialist

As you can see, there are many ways to install a subwoofer – or any speaker, for that matter. Navigating the available space in the vehicle, as well as different speaker sizes and designs, can be tricky. The design and construction of an enclosure can be complex, especially when complex shapes are involved. Visit your local car audio specialist retailer to explore different enclosure options for your vehicle.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.