Beyond the features and design of a subwoofer, no single factor affects the performance of a subwoofer system more than car audio subwoofer enclosures and their design. There are several popular enclosure design options available, each with their own unique set of benefits and drawbacks. The most popular enclosures are an acoustic suspension (sealed) and bass reflex (vented or ported) designs. We will close this “Bang For Your Buck” subwoofer discussion with a quick look and bandpass style enclosures.

Acoustic Suspension Subwoofer Enclosures

Acoustic suspension subwoofer enclosures are quite simply a sealed cabinet that adds to the compliance of the subwoofer system. This added compliance acts as a high-pass filter and reduces bass output, but also serves to increase excursion-limited power handling. If you look at the graphs below, the yellow curve shows a high-quality 10-inch car audio subwoofer in a 1.2 cubic foot acoustic suspension enclosure. The red curve shows the frequency response of the same subwoofer in a 0.5 cubic foot enclosure.

As you can see, above 60Hz, the smaller enclosure is a little bit louder but remains within a decibel or two. Below 50Hz is where things start to vary more. The larger enclosure is 2.15 dB louder at 35Hz and 3.35 dB louder at 25 Hz. While it might not appear dramatic, 3dB is the equivalent of having twice as much power driving the subwoofer. However, this increase in efficiency comes with no thermal power handling penalty.

Speaking of power handling, we should look at the physical power handling limits of these subwoofers based on cone excursion. The subwoofer in question has an Xmax specification of 19 mm in each direction from its rest position. The graph below shows the predicted cone excursion of the subwoofer when driven with 500 watts (the maximum power for which it is rated).

Once again, above 60Hz, there is minimal difference in the excursion between the two drivers. Below that, the larger volume of air in the big enclosure has less effect on the stiffness of the subwoofer system. The result is the subwoofer moves farther for each watt of power. If you compare the excursion graph to the frequency response graph, the efficiency levels are directly correlated.

As a summary, sealed enclosures are the simplest to design and are the most forgiving of construction errors regarding net volume. In most cases, sealed enclosures are also the smallest, making them extremely popular.

Bass Reflex Subwoofer Enclosures

The second popular option for a subwoofer enclosure is a bass reflex design. In this enclosure, a vent is added to the enclosure and is tuned to resonate at a specific frequency to increase the output of the system. If we take our 1.2 cubic foot enclosure and add a vent that is tuned to 30 Hz, you can see in the red curve on the graph below that we pick up an astonishing 6.9 dB of output at 30 Hz.

Now, while most vented enclosures are larger than their sealed brethren, the benefit is often an increase in output that is potentially more than having two subs in a sealed design. In fact, this vented design is louder from 20 to 60Hz than three identical subs in an enclosure that is 50% larger (1.8 cubic feet).

Besides efficiency, there is a second benefit to a bass reflex enclosure design. Cone excursion is dramatically reduced through the majority of the operating range. The graph below shows the cone excursion vs. frequency response of the 1.2 cubic foot sealed (yellow) and vented (red) enclosures. The null (reduction in excursion) at 30 Hz is caused by the tuning of the vent. At this frequency, the majority of the output from the subwoofer system comes from the vent itself.

This reduction in cone excursion increases physical power handling and also reduces distortion – as long as you have designed and constructed the vent properly. Vents need to have a large enough area so that air velocity in the vent is kept to a minimum. The mouth of the vent also needs to have a large radius

As with anything, there are always drawbacks. There is very little cone motion control below the tuning frequency of a bass reflex enclosure. In this 1.2 cubic foot vented design, the driver will reach its 19mm excursion limit at 22Hz when driven with 500 watts of power. Below that frequency, the sub will move more than it’s rated for and distortion will increase dramatically. This excursion issue can be offset by implementing an infrasonic (high-pass) filter around 20 Hz to reduce the power sent to the driver. Many subwoofer amplifiers have infrasonic filters built-in. Most digital signal processors can do the same thing.

Bandpass Subwoofer Enclosure Designs

Bandpass enclosures are called that because they not only act as a high-pass filter but as a low-pass filter as well. A typical bandpass enclosure features two chambers. The woofer is mounted between these chambers. In a single-tuned enclosure (often referred to as a fourth-order bandpass or single- reflex bandpass), one of the chambers includes a vent from which all the sound is created. A benefit of this design is the ability to feed that vent through an opening in a rear parcel shelf or similar to ensure coupling with the interior of the vehicle.

The second bandpass enclosure design is a Double-tuned design where both the front and rear chambers are vented. In a Series-tuned bandpass enclosure, the large rear chamber vent feeds into the front chamber. In a parallel-tuned design, the vents from each chamber feed directly into the listening area. Double-tuned bandpass designs are often referred to a sixth-order or dual-reflex designs.

Depending on the type of bandpass enclosure you choose to construct, you may gain some significant excursion-based power handling, and some overall system efficiency through it’s operating range. The main drawback of a bandpass enclosure is its complex design and sensitivity to construction errors. Unlike a simple sealed enclosure, errors in speaker parameters and simulations can produce unpredictable and potentially unwanted results.

The second challenge posed by bandpass design lies in the lack of mid-bass they produce. The low-pass filter abruptly reduces (relatively) high-frequency output. This filtering effect can make it very difficult to achieve a smooth transition between the output of a subwoofer system and the midrange or mid-bass drivers in a system.

The third challenge of a bandpass enclosure is the physical size. Put simply, if you expect low-frequency performance similar to a typical bass-reflex design, the bandpass enclosure will be physically larger. With space at a premium in modern vehicles, this could be reason enough to avoid them.

Picking the Right Enclosure for Your Vehicle

In most systems, the choice of enclosure design will come down to the space available. If you are trying to minimize the impact of a subwoofer on the available storage space in your vehicle, a sealed enclosure may be the best choice. If you want increased efficiency, then consider a bass-reflex design. If you have a unique application that requires a bandpass design, then by all means, go for it. But be prepared to pay more for the required design, fabrication and testing time required to get these enclosures perfect.

A quick note on “basic” subwoofer systems. Over the years, we’ve seen a LOT of retailers offer “bass packages” that include a sub, amplifier, enclosure and often a wiring kit. In the majority of these packages, the retailer has paired an inexpensive sub with an inexpensive amp and a sealed subwoofer enclosure to minimize the total cost of the system. When you are limited in power and output capabilities, upgrading these packages to a bass reflex enclosure is a great investment. You will typically double the efficiency of the system and reduce the chances of damage to the driver caused by overpowering it.

When it’s time to pick a subwoofer enclosure for your vehicle, work with your local mobile enhancement retailer. They will help design a solution that will balance your performance and space expectations. It’s not a complicated process, but, having someone with experience will make it much easier and more predictable.

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.

No single upgrade to an audio system offers a larger improvement in sound quality than the addition of a car audio subwoofer. Adding a subwoofer not only improves the low-frequency performance of your sound system, it can also improve the clarity of the entire system and enhance the volume level capabilities of the smaller speakers in your car. In this issue of Bang for Your Buck, we are going to look at a few popular subwoofer upgrade options available for adding bass to your vehicle.

What is a Car Audio Subwoofer?

In the simplest of terms, a subwoofer is a large speaker designed to play frequencies below 100 Hz at relatively high output levels. Subwoofers are most commonly available in 10- and 12-inch sizes, but 6.5-, 8-, 13.5- and 15-inch subs are also readily available.

To reproduce low-frequency information with authority, a speaker has to move a lot of air. In fact, for every octave lower a speaker is to play, it has to move four times as far to produce the same volume level. If your sub is moving 1 mm back and forth at 80 Hz, it has to move 4 mm at 40 Hz and an impressive 16 mm at 20 Hz. Most people find a pulsing bass line of 40–50 Hz to be fun. That said, feeling the rumble of deep bass like the introduction to “Boom Boom Pow” by the Black Eyed Peas or the pulse in Pink Floyd’s “Time” can cause goosebumps.

Subwoofer Power Handling

Most people associate subwoofers with their power-handling capabilities. While not a direct determining factor in the quality of a subwoofer, power handling is important in terms of choosing the right subwoofer for your sound system. If you want to listen to your sound system at high volume levels, you need powerful amplifiers and speakers that can handle that power while being able to move adequately to reproduce sound at high levels. It is no surprise that the output and power handling are directly related, since it takes amplifier power to make a speaker cone move.

Picking “enough” subwoofer depends on several factors. How loud is loud enough? How much space can you afford to give the subwoofer system? How powerful of an amplifier can your vehicle’s electrical system support? It can be difficult to choose the right sub based on these criteria, especially since different vehicles offer different amounts of cabin gain. Would a single 10-inch sub in a sealed enclosure in the back of a Honda Fit be a suitable solution in a Cadillac Escalade or short-cab Ford F-150?

Custom-built Subwoofer Solutions

Your best choice to upgrade your vehicle with a subwoofer is to have your local mobile electronics specialist retailer design and construct a subwoofer system that is specific to your vehicle and your expectations. This process will start with your input in determining just how much bass you want. From there, your system designer can suggest a subwoofer or subwoofers that will meet your expectations.

The next step is to decide where to install the subs. The simplest of custom enclosures would be a rectangular wooden cabinet that sits in the trunk or cargo area of your vehicle. The dimensions of the enclosure can be optimized to make the most use of the available space. This optimization may include angling the back of the enclosure to follow the angle of the seats.

Depending on your goals and expectations, you may choose to have the enclosure finished in a material that matches the interior. For a more-customized look, you may want the enclosure wrapped in vinyl that is the same color and grain as the trim panels in your vehicle.

If you want something truly unique, then ask about including LED lighting in the enclosure. You can choose to have a Lexan or Plexiglas window added and illuminate the interior of the enclosure or add acrylic plastic accent pieces that light up. Upgrades at this level are often combined with enclosures finished with multiple materials – different colors of vinyl can provide amazing cosmetics.

Advanced Subwoofer Enclosure Designs

The next step, beyond a simple wooden enclosure, would be one that is shaped to fit the unique contours of your vehicle. Enclosures of this type are often built using a combination of wood and fiberglass or layers of wood that are stacked one on top of another to create complex contours. The most-common application like this is where a subwoofer is being fitted into the corner of a trunk or hatch area, but is also often placed under the trunk floor in a spare tire well. The passenger-side footwell of a two-seat vehicle is another popular location for this type of enclosure.

Due to the complexity of these enclosures, they will typically cost more. The trade-off is that they integrate better into your vehicle – providing you with the acoustic performance you want without taking up valuable cargo area.

Application-specific Subwoofer Systems

Companies like JL Audio, MTX and Kicker offer subwoofer systems designed for specific models of vehicles. These enclosures are designed to offer impressive performance while minimizing how much space they use. Some companies construct these enclosures from fiberglass in large molds, while others use thick plastics. In most cases, while these enclosures are visible once installed, they are available in materials that match the color of the vehicle interior. An application-specific enclosure is a great way to add amazing bass to a vehicle quickly and efficiently.

A subsection of these application-specific enclosures is truck boxes. No, not the thin, wedge-style enclosures that fit behind the seat, but complex enclosures that use the space under a rear bench seat in a pickup. Companies like Audio Enhancers, Bassworx and Atrend offer cost-effective solutions that will accept the subwoofer of your choice. In most of these applications, you need a shallow subwoofer because mounting depth is quite limited.

Shallow Subwoofers

You’ll note that we haven’t discussed the specific features of subwoofers that differentiate one from another. This omission is quite deliberate because we will dedicate an entire article to that topic. In the meantime, it is worth discussing the difference between a conventional subwoofer and a shallow-mount design.

Shallow subwoofers were originally designed for use behind the seat of a pickup truck. Shallow cones, baskets and motor structures provide mounting depths of around 3 to 3.5 inches. Historically, the tradeoff for this reduced mounting depth has been a dramatic decrease in cone excursion capability. Over the past few years, companies like JL Audio, Illusion Audio, Kicker, Focal, Rockford Fosgate, ARC Audio and Audiomobile have worked hard to maximize the performance of their shallow-mount subwoofers to the point that they offer similar, if not better, performance than some conventional designs.

Audition a Subwoofer System Today!

We will leave you with this as the starting point for choosing a subwoofer solution for your vehicle. In the next article, we’ll explain the performance benefits and drawbacks of different subwoofer enclosure designs, then wrap up our buyer’s guide series with an explanation of advanced subwoofer design features that offer audible improvements in performance. Until then, visit your local specialist mobile enhancement retailer and audition one of their demo vehicles that has a subwoofer. We are sure you’ll be impressed and want one for your car or truck.
No single upgrade to an audio system offers a larger improvement in sound quality than the addition of a car audio subwoofer. Adding a subwoofer not only improves the low-frequency performance of your sound system, it can also improve the clarity of the entire system and enhance the volume level capabilities of the smaller speakers in your car. In this issue of Bang for Your Buck, we are going to look at a few popular subwoofer upgrade options available for adding bass to your vehicle.

What is a Car Audio Subwoofer?

In the simplest of terms, a subwoofer is a large speaker designed to play frequencies below 100 Hz at relatively high output levels. Subwoofers are most commonly available in 10- and 12-inch sizes, but 6.5-, 8-, 13.5- and 15-inch subs are also readily available.

To reproduce low-frequency information with authority, a speaker has to move a lot of air. In fact, for every octave lower a speaker is to play, it has to move four times as far to produce the same volume level. If your sub is moving 1 mm back and forth at 80 Hz, it has to move 4 mm at 40 Hz and an impressive 16 mm at 20 Hz. Most people find a pulsing bass line of 40–50 Hz to be fun. That said, feeling the rumble of deep bass like the introduction to “Boom Boom Pow” by the Black Eyed Peas or the pulse in Pink Floyd’s “Time” can cause goosebumps.

Subwoofer Power Handling

Most people associate subwoofers with their power-handling capabilities. While not a direct determining factor in the quality of a subwoofer, power handling is important in terms of choosing the right subwoofer for your sound system. If you want to listen to your sound system at high volume levels, you need powerful amplifiers and speakers that can handle that power while being able to move adequately to reproduce sound at high levels. It is no surprise that the output and power handling are directly related, since it takes amplifier power to make a speaker cone move.

Picking “enough” subwoofer depends on several factors. How loud is loud enough? How much space can you afford to give the subwoofer system? How powerful of an amplifier can your vehicle’s electrical system support? It can be difficult to choose the right sub based on these criteria, especially since different vehicles offer different amounts of cabin gain. Would a single 10-inch sub in a sealed enclosure in the back of a Honda Fit be a suitable solution in a Cadillac Escalade or short-cab Ford F-150?

Custom-built Subwoofer Solutions

Your best choice to upgrade your vehicle with a subwoofer is to have your local mobile electronics specialist retailer design and construct a subwoofer system that is specific to your vehicle and your expectations. This process will start with your input in determining just how much bass you want. From there, your system designer can suggest a subwoofer or subwoofers that will meet your expectations.

The next step is to decide where to install the subs. The simplest of custom enclosures would be a rectangular wooden cabinet that sits in the trunk or cargo area of your vehicle. The dimensions of the enclosure can be optimized to make the most use of the available space. This optimization may include angling the back of the enclosure to follow the angle of the seats.

Depending on your goals and expectations, you may choose to have the enclosure finished in a material that matches the interior. For a more-customized look, you may want the enclosure wrapped in vinyl that is the same color and grain as the trim panels in your vehicle.

If you want something truly unique, then ask about including LED lighting in the enclosure. You can choose to have a Lexan or Plexiglas window added and illuminate the interior of the enclosure or add acrylic plastic accent pieces that light up. Upgrades at this level are often combined with enclosures finished with multiple materials – different colors of vinyl can provide amazing cosmetics.

Advanced Subwoofer Enclosure Designs

The next step, beyond a simple wooden enclosure, would be one that is shaped to fit the unique contours of your vehicle. Enclosures of this type are often built using a combination of wood and fiberglass or layers of wood that are stacked one on top of another to create complex contours. The most-common application like this is where a subwoofer is being fitted into the corner of a trunk or hatch area, but is also often placed under the trunk floor in a spare tire well. The passenger-side footwell of a two-seat vehicle is another popular location for this type of enclosure.

Due to the complexity of these enclosures, they will typically cost more. The trade-off is that they integrate better into your vehicle – providing you with the acoustic performance you want without taking up valuable cargo area.

Application-specific Subwoofer Systems

Companies like JL Audio, MTX and Kicker offer subwoofer systems designed for specific models of vehicles. These enclosures are designed to offer impressive performance while minimizing how much space they use. Some companies construct these enclosures from fiberglass in large molds, while others use thick plastics. In most cases, while these enclosures are visible once installed, they are available in materials that match the color of the vehicle interior. An application-specific enclosure is a great way to add amazing bass to a vehicle quickly and efficiently.

A subsection of these application-specific enclosures is truck boxes. No, not the thin, wedge-style enclosures that fit behind the seat, but complex enclosures that use the space under a rear bench seat in a pickup. Companies like Audio Enhancers, Bassworx and Atrend offer cost-effective solutions that will accept the subwoofer of your choice. In most of these applications, you need a shallow subwoofer because mounting depth is quite limited.

Shallow Subwoofers

You’ll note that we haven’t discussed the specific features of subwoofers that differentiate one from another. This omission is quite deliberate because we will dedicate an entire article to that topic. In the meantime, it is worth discussing the difference between a conventional subwoofer and a shallow-mount design.

Shallow subwoofers were originally designed for use behind the seat of a pickup truck. Shallow cones, baskets and motor structures provide mounting depths of around 3 to 3.5 inches. Historically, the tradeoff for this reduced mounting depth has been a dramatic decrease in cone excursion capability. Over the past few years, companies like JL Audio, Illusion Audio, Kicker, Focal, Rockford Fosgate, ARC Audio and Audiomobile have worked hard to maximize the performance of their shallow-mount subwoofers to the point that they offer similar, if not better, performance than some conventional designs.

Audition a Subwoofer System Today!

We will leave you with this as the starting point for choosing a subwoofer solution for your vehicle. In the next article, we’ll explain the performance benefits and drawbacks of different subwoofer enclosure designs, then wrap up our buyer’s guide series with an explanation of advanced subwoofer design features that offer audible improvements in performance. Until then, visit your local specialist mobile enhancement retailer and audition one of their demo vehicles that has a subwoofer. We are sure you’ll be impressed and want one for your car or truck.

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.

When it comes to designing car audio systems, retailers need to take into account how their clients want their music to sound. Everyone seems to have different preferences for the amount of bass or high-frequency content. These tonal balance preferences can change based on the choice of music and the listener’s mood. In most cases, a well-designed sound system can handle any music listening preferences.

A preference that is harder to change is where the music seems to come from. Many mobile audio aficionados prefer the music to come from a virtual soundstage as much in front of them as possible. Many people also prefer their music to wrap around them, with as much coming from behind as in front.

There is no right or wrong, so long as you are happy with the way your system sounds.

In this article, we discuss how the client’s preferences can affect the way a mobile audio system is designed. We’ll also look at a few options for the performance of these systems.

Recording Studio Sound

Up until recently, most recording studios used a pair of high-quality speakers placed equidistantly in front of the mixing console. The recording engineer would balance the level and placement of the instruments and performers, using these speakers as his reference. The result was a soundstage that spanned the distance between the speakers.

Attending an outdoor concert may yield a similar listening experience. In a venue like that, the sound comes from in front of you – be it the sound created directly by the instruments, or from the PA gear set up on or beside the stage.

In your car, this can be recreated by focusing on the placement and quality of the front speakers. A good set of components can offer similar performance. Adding a digital signal processor (DSP) can dramatically improve the accuracy of the system by compensating for frequency response, arrival time and speaker volume level differences. When you listen to a quality recording, each performer will seem to be in a specific location on the soundstage.

What about Club Sound?

There are lots of ways to describe the experience of having the music come from all around the vehicle, but the analogy of a nightclub or – as we old fogies like to call them – a disco might work best. The concept here is that the music will seem to come from all around you. Unlike a performance where you can point to the source of sound from each instrument, it envelops the listening space. In most of these systems, we still balance the system with dedicated left and right channels.

What about those cars and trucks with all the PA speakers in the doors? Not a pair of speakers, but something like eight speakers in each door, with several high-efficiency bullet tweeters. In these designs, if indeed the goal is sheer volume, it might make more sense to forego keeping the music in stereo and use a processor to combine the left and right channel, so it’s simply as loud as possible.

You Haven’t Mentioned a Concert Hall

You may have noticed that we haven’t talked about a live performance that takes place in a concert hall or indoor venue. This has been quite deliberate.

Imagine heading out for dinner to a local restaurant that has a small band playing. Maybe it’s rock music with a guitarist, bassist, drummer and lead singer. Or perhaps it’s a three-piece jazz ensemble with a piano, saxophone and upright bass. If the performance is acoustic, other than for an amp for an electric guitar or bass, the source of the music will be easy to define as coming from the instruments – but that isn’t the extent of the experience.

Every confined space, except an anechoic chamber, causes the sound to reflect off the floors, walls and ceiling. You hear the music directly from the instrument or performer first, then those same sounds as they reflect off objects and surfaces. The total experience is defined by the mixture of all these sounds.

Live Performance Sound

A great example of a live performance sound would be a venue like the Ryman Auditorium in Nashville. Known primarily as the home of the Grand Ole Opry, this amazing auditorium continues in operation today and has hosted performers like Bruce Springsteen, Mumford and Sons, Tom Petty, the Foo Fighters, Coldplay and Kesha, along with classic country music performers. The Ryman Auditorium is considered by many as having the best acoustics in the world. Coldplay said it is “the greatest theatre in the world,” bested only by the Mormon Tabernacle in Salt Lake City.

What does this mean? If you have been to the Ryman or the Mormon Tabernacle, you know that these spaces have distinctive echoes, reflections and reverberations. You can quite literally hear a pin drop on the stage from almost any seat in the house. It is this incredible live sound that performers and attendees enjoy. How do we recreate that experience in our cars and trucks?

If the music you are listening to was recorded in a live venue and not in a studio, then the reflections and reverberations will be contained in the recording. Recordings of orchestras and choirs performing classical music are good examples of this. If your sound system is tuned well and offers an accurate soundstage with excellent imaging, it will reproduce the ambiance and a sense of the room size of these recordings.

Signal Processing Solutions

Another option is to use a signal processor to create a sense of room size. In the 1990s and 2000s, lots of processors had presets for jazz, concert and club settings that added reverberation and delay to dedicated rear channel outputs. These technologies have evolved to more-advanced processing algorithms like Bose Panaray and Quantum Logic Surround from Harman. These systems can analyze the content of a stereo recording and extract information that should be reproduced by side and rear speakers to create an immersive listening experience. If your vehicle has one of these technologies, your local mobile enhancement retailer can make it sound even better by adding a premium subwoofer system, since factory stereo systems rarely offer great bass performance.

The forthcoming Audiofrog Multiseat processor works similarly, analyzing the content of the music and directing it to left, center, right, left and right side, and left and right rear speaker outputs. Sure, you need a lot of speakers and amplifier channels to make full use of the system, but enjoying a realistic musical experience from any seat in the vehicle is worth the effort.

What to Know Before Going Shopping

If you want to upgrade the sound system in your car, truck or SUV, do a little homework before you start shopping. Play with the fader control in your car to determine how you want the new system to sound. If you can tell the salesperson how you want your new system to sound, they can help you choose the right products much more quickly and let the installer know how to configure the system so it sounds exactly the way you want. If you aren’t sure which you prefer, ask if they have a demo vehicle you can audition. That’s a great way to experience a high-end audio system.

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.