If you want the window-rattling bass that only a subwoofer can deliver but don’t have enough trunk room, don’t worry! A Free Air subwoofer provides deep bass without taking up a lot of room. You don’t need to build or buy a free air subwoofer because your car’s trunk serves as the container for the bass to resonate in. It will not only save you space, but it will also save you money. It’s easy to install, saving you hours of time building a box.
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Pioneer TS-SW2002D2 8-inch Shallow-Mount Subwoofer with 600 Watts Max Power
- 10 in. subwoofer
- 1,200 watts max, 300 watts RMS
- Frequency response: 20 Hz to 900 Hz
The Pioneer TS-SW2002D2 Shallow-Mount Subwoofer is one of the Best Free Air Subwoofers. It produces high-quality audio with deep bass. The 8-inch subwoofer has an RMS output of 150 watts and a peak power of 600 watts. The mica injection-molded plastic cone produces more precise and booming bass. The TS-SW2002D2 is only 2 5/8 inches deep. The Pioneer Shallow-Mount subwoofer is intended to offer high-quality sound in areas where typical subwoofers will not fit.
The TS-SW2002D2 is a miniature subwoofer with an 8-inch driver and a shallow mount style that allows it to fit into tight locations. With a width of less than 3 inches, it allows you to enjoy strong bass in a small place. The Pioneer air subs can be put either free-air or in an enclosure, depending on your space constraints and requirements.
Despite its diminutive size, it packs a punch, capable of handling up to 150W RMS using a variety of amplifiers. The 2 Ohm voice coil may be wired for 1 or 4 Ohm settings, giving you the flexibility to match your amp. It has a wide frequency response range of 20 to 200 Hz, which is more than enough to pick up on the low frequency ranges that cause your automobile to shake.
It’s also a long-lasting free-air subwoofer with a Mica-injected resin cone that’s both hard and light, allowing it to fire at high pressures without distorting the sound waves. This design is able to move more air than previous versions, resulting in a bass response that is both powerful and accurate. The TS-SW2002D2 isn’t going to provide audiophile quality sound, but it does a good job as a step up over a basic subwoofer.
The Pioneer subwoofer does have some shaking at higher volumes, which is our sole issue. The Pioneer TS-SW2002D2 entry-level free air subwoofer, on the other hand, won’t let sound engineers down if you’re trying to update your automobile sound system.
Kicker 10C104 Comp 10-Inch Subwoofer 4 Ohm
- New for 2017!
- Injection-Molded Polypropylene Cone
- Perimeter Venting for Thermal Management
The Kicker 10C104 is one of the best free-air subwoofers on the market. It’s 10-inches in diameter and capable of handling a reasonable quantity of power on a continual basis. The sensitivity rating of the Kicker Comp 10C104 is 86 dB. It has a maximum RMS power of 150 watts peak power. It can be used in both sealed and ported enclosures, as well as free-air applications.
A well-known name in the automobile audio sector is Kicker. They’ve been around for a long time and have mastered the art of producing build quality automotive audio systems at an affordable price tag. From automotive speakers and subwoofers to automobile amplifiers and signal audio processors, Kicker has it all. The majority of their automobile subwoofers are made to be as adaptable as possible. As a result, they can be installed in both sealed and vented boxes, as well as on an Infinite Baffle .
The Kicker 10C104 has a flex-resistant polypropylene cone with 360-degree back bracing for distortion-free hard-hitting lows. The ribbed foam surround provides lengthy excursion and maintains the cone on target, while the double stitching assures consistent performance under severe bass load.
This woofer is constructed with a strong steel basket that provides a solid base for powerful bass. It has a ribbed foam rim and a thick injection-molded polypropylene cone. The ribbed foam rim allows for lengthy excursion and maintains the cone on target, while double stitching prevents your sub from coming apart at the seams.
To ensure long-term performance, this air systems has a sturdy motor structure with plenty of ventilation. Because of its 4-ohm impedance, it may be used with almost any amplifier on the market.
The only issue we have with this subwoofer is its low sensitivity rating of 86 dB. To get a high sound output, sensitivity must be combined with power. Simply said, a model with a higher sensitivity requires less power to create the same quantity of sound as one with a lower sensitivity.
JBL S3-1224 12″ SSI Subwoofer
- Power Handling (Peak): 1500 W
- Sensitivity: 92dB
- Power Handling (RMS): 500W
In the loudspeaker sector, JBL is one of the most well-known brands when it comes to making the Best Free Air Subwoofers. The company has been in operation for a long time and has mastered the art of producing high-quality products. They’ve launched everything from home audio systems to headphones, all while maintaining a high standard of quality. Similarly, their range of automotive speakers and subwoofers is impressive.
JBL’s S3-1224 is one of the greatest free-air subwoofers on the market. It has a 12-inch diameter and can handle a reasonable amount of electricity on a regular basis. The sensitivity of the JBL S3-1224 is 92 dB, and it can take up to 500 watts RMS. It has a frequency response of 25Hz to 175Hz and can be used in sealed and ported enclosures as well as free-air applications.
This JBL 12 inch subwoofer features a three-inch (75mm) voice coil, which makes it lighter than subwoofers with four-inch voice coils and capable of handling more power than traditional two-inch voice coils. This achieves the ideal combination of thermal power handling and low mass.
When it comes to thermal management, this JBL free air subwoofer features an innovative aero-cooled voice coil design that provides long-term durability and consistency. The SSI (Selectable Smart Impedance) technology that this 12 inch free air subwoofer has sets it different from other subwoofers on the market. By just turning a little switch, SSI allows you to select the best impedance—2 or 4 ohms. This provides more flexibility and a wider range of system configurations.
Overall, the JBL S3-1224 is for you if you want a reasonably priced free air subwoofer with more power, more reliability, more versatility – and no sacrifices.
Infinity Kappa 1200W 12″ 1200 Watt Car Audio Subwoofer
- Most car audio system designs call for 2- or 4-ohm impedance. Kappa Series subwoofers put the choice in your hands. A proprietary HARMAN technology,...
- The Kappa Series voice coil employs a two-sided, ducted airflow design that cools the voice coil, increases power handling and improves reliability....
- Kappa subwoofer cones incorporate glass-fibers for exceptional accuracy and detail. Inherently nonresonant, the glass-fiber cones eliminates...
Infinity is one of the most well-known and well-respected brands in the audio industry. They have been in operation since 1968. The company has developed a wide range of products, from home audio systems to automobile audio components, all while maintaining a high degree of quality.
Subwoofers from Infinity have always set themselves apart from the competition. The Kappa 1200W subwoofer from Infinity is no exception. It’s one of Infinity’s top-of-the-line 12-inch subwoofers. For excellent accuracy and detail, the subwoofer is equipped with an acoustically damped glass-fiber cone. The glass-fiber cones reduce distortion due to their non-resonant nature, allowing your bass to come through loud and clear.
The internal components support Infinity’s passion for modern technology once you get past the refined exterior. Selectable Smart Impedance (SSI) technology is included into this subwoofer, allowing you to create exactly the free air speakers you want without having to deal with difficult wiring. With the flip of a switch, the subwoofer may operate at 2 Ohms or 4 Ohms. If you’re planning on upgrading your car audio system in the future, this free air subs makes it simple to do so – plus it’s practically impossible to connect wrong.
A steel basket with voice coil vents is included with the Infinity Kappa 1200W subwoofer. This basket serves as a strong foundation for the subwoofer, which can withstand 500 watts RMS of power. Furthermore, this sub can reach frequencies as low as 23Hz, resulting in detailed and precise bass. This adaptable sub works well in sealed or ported enclosures and is excellent for free-air applications as well.
Rockford Fosgate R2 Ultra Shallow 10-Inch 4 Ohm DVC Subwoofer
- Stamp-cast basket with integrated spider venting
- Mica injected polypropylene cone
- Mounting Depth 3.4 Inches ; 12 AWG compression terminals
The R2 Ultra Shallow Subwoofer from Rockford Fosgate features a peak power of 400 watts and an RMS power of 200W RMS. For improved sound production, the basket has spider venting built in. The voice coil is composed of anodized aluminium, and the mica injected polypropylene cone is robust. There’s also a linear spider with stitched 16 AWG tinsel leads and 12 AWG compression connections.
The Rockford Fosgate R2 has a mounting depth of 3.4 inches, so it’s not as shallow as some of the other subwoofers on our list, despite the name. This type of equipment may be the correct choice for you if you enjoy putting free air subwoofers in your automobile or truck. It has a spider ventilation system that keeps your subwoofer from overheating and produces superb sound quality.
It’s another another heat management technology that’s present in the majority of high-end subwoofers, making it a safe bet. This handy subwoofer may also be simply installed or moved within the automobile due to its modest size.
CT Sounds TROPO-12-D2
- 12" dual 2-ohm car subwoofer with RMS Power: 650 Watts RMS; Max Power: 1300 Watts MAX; Coil Configuration: Dual 2 Ohm
- 2.5 Inch - 4 Layer High-Temperature Copper Voice Coil & Double Slug Y30 Grade Optimized Motor
- Flexible High Foam Surround & 3% Carbon Fiber Reinforced Cone
CT Sounds offers a range of subwoofer lines, with the Tropo series emphasising low-frequency coverage with each other strong volume and punchy bass. With a 12-inch driver that can handle up to 600W RMS, you can anticipate a lot of volume from this sub. This booming bass is more than enough to get your car or truck in the mood for a party.
The Tropo’s power originates from its high-grade, double-stacked Y35 magnet, which can easily bear the intense pressure of low frequencies. A heavy-duty stamp steel basket, foam surround, double-stitched competition-grade paper cone, and two high-temperature voice coils are among the other robust design characteristics.
These components work together to produce a bass that is clean and distortion-free without sacrificing power. Because of its high quality construction, the CT Sounds sub is classified as competition-grade, so you can count on it to last.
The CT Sounds subwoofer has a lot of bass, but some customers say it suffers with frequencies below 35Hz. As a result, if you want bass-heavy music with a lot of low frequencies, this may not be the finest free air sub for you.
Rockford Fosgate P3S D2-8 Shallow-Mount Car Subwoofer
- The Rockford Fosgate P3S series shallow mount subwoofers deliver Punch, designed to deliver big bass in a tight space, with its low profile mounting...
- The Punch P3SD2-8 is a slim 8” 2-Ohm DVC (dual voice coil) subwoofer with 150 Watts RMS / 300 Watts Max power handling and custom 10-AWG nickel...
- Featuring anodized aluminum cones and dustcaps, with a unique spider venting design to keep the motor cooler and a new hybrid stamp-cast basket...
The Rockford Fosgate P3S was created with both sealed and vented enclosures in mind. It only has a 2.66-inch mounting depth. The cones are made of metal that has been anodised. It’s a twin voice coil 2 Ohm type with an RMS power of 150 watts. The push terminals are nickel-plated 10 AWG. The subwoofer from Rockford Fosgate comes with a one-year limited warranty.
Punch Stage 3 subwoofers from Rockford Fosgate are part of a lengthy line of high-performance subs that offer true bass. Punch Stage 3 shallow-mount subwoofers now make it easier to get remarkable low end in smaller or difficult-to-fit automobiles.
Thanks to excellent materials and engineering, the P3SD2-8 8″ shallow subwoofer can keep up with its bigger brothers. The cone and dust cover are made of anodized aluminium, making the woofer light and easy to drive while remaining stiff enough to keep its shape under maximum load. The M-Roll SantopreneTM surround also has good excursion for maximum output while still being long-lasting.
The subwoofer is housed in a low-profile frame with plenty of venting to prevent overheating and thermal failure. With a depth of 2-5/8 inches, this sub can go where no bass has gone before – simply design a bespoke enclosure or find a suitable box. The two 2-ohm voice coils allow you to connect additional subs or coax the most out of your amplifier.
Wet Sounds XS-10FA-S4V2
- Protective Grille - Keeps your subwoofers safe and sound
- Optimized for Infinite Baffle (Free Air) applications or 1.3 cu ft sealed enclosure
- RMS watts each: 300 Watts
Here’s a little something for all of you boaters out there. Authentic marine subwoofers are difficult to come by, which explains the uproar around the Wet Sounds XS-10FA-S4V2 subwoofer. The creators of this one-of-a-kind invention wanted to provide boaters with a capable partner to accompany them on deep-sea expeditions. The XS-10FA-S4V2 features a Bass upsurge that is sure to have the docks rocking.
This package is designed exclusively for boat-free air applications, and it includes two XS-10FA-S4V2 subwoofers, each rated at 300 Watts RMS. Each of these subwoofers has a peak power output of 600 watts. Its frequency response range of 25-500Hz allows it to handle low sounds with ease. The entire chassis of the Wet Sounds XS-10FA-S4V2 is nothing short of opulent. It’s proving to be an attractive addition to any boat, with a contemporary silver protective grill.
Knowing how hard the salty maritime environment can be, its designers made cautious to equip it appropriately. Some of the mitigating features include a powder-coated aluminium frame, a magnet boot, and gold-plated connectors to assist it avoid moisture-related damage. With that, you can relax while the XS-10FA-S4V2 heats things up.
A submarine designed to resist deep-sea conflicts is no laughing matter. When it comes to delivering a punch, the Wet Sounds XS-10FA-S4V2 means business; it will enliven any journey, no matter how bleak it may appear.
Infinity Reference REF1200S 12″ Shallow Mount Subwoofer
- Low-profile design
- Harman-proprietary SSI (Selectable Smart Impedance)
- 92dB Sensitivity
The REF1200S is a 12-inch subwoofer with a compact design that allows it to fit into tighter spots in your car or truck. It has a shallow mount design that is easy to install and won’t take up any valuable trunk space. Depending on your space constraints and bass requirements, you may install this sub in a free-air or enclosed configuration.
The variable impedance of the Infinity Reference subwoofer is one of its greatest features, enabling you to choose between 2 and 4 Ohm. This best free air 12 inch subwoofer gives you more flexibility and ease of installation by allowing you to modify according to your amplifier and audio arrangement. It’s also quite durable, as Infinity Reference, like JBL, puts their subwoofers through reliability testing. Freezing, baking, shaking, UV radiation exposure, and continuous operation for several days are among them. After these rigorous tests, you can rest assured that this free-air subwoofer can stand up to any abuse you throw at it.
While the REF1200S has a good frequency response from 27 to 175 Hz, some customers have complained that it isn’t as good at low frequencies. If you’re searching for a loud, wall-shaking bass, this isn’t the subwoofer for you. However, if you value dependability, musical sound, and genuine bass, the Infinity Reference REF1200S subwoofer is the one for you.
Kicker CompRT 43CWRT672
- Size: 6.5"
- Impedance: 2 Ohms DVC
- Power Watts: 300W Peak / 150W RMS
This is another terrific Kicker free air sub, but this time the subwoofer is on the smaller side. That isn’t to imply it isn’t capable of delivering results. To be honest, the subwoofer in question is built to operate similarly to a full-size sub, but without taking up all of your cargo space.
Kicker’s CompRT 43CWRT672 subwoofer has two 2-ohm voice coils and measures 6-3/4 inches in diameter. With a height of less than 3 inches, you have a lot of installation possibilities. It could be a great substitute for a factory-installed subwoofer (a little trimming might be required).
The sturdy injection-molded polypropylene cone on this subwoofer won’t flex and produce distortion when you crank up the bass. Its cone is centered and supported by a heavy-duty Santoprene rubber ring, allowing for long-lasting performance that won’t break down when the bass gets heavy.
This little sub may make a huge impact in terms of bass and sound quality if properly powered. The subwoofer in question can handle up to 150 watts RMS, so make sure you have a good amp to supply it. Furthermore, for a subwoofer of this size, this sub can touch as low as 30Hz, which is rather impressive.
You can connect the twin voice coils for either 4- or 1-ohm total impedance when it comes to wiring, giving you more options when setting up your system. This subwoofer is not only compatible with free-air installations, but it also sounds terrific in a sealed enclosure.
Planet Audio AC10D 10 Inch Car Subwoofer
- Dimensions: 11 x 11 x 5.3 inches
- Impedance: 4 ohms
- Mounting Depth: 4.8 inches, Mounting Hole: 9.1 inches
Planet Audio creates high-quality audio at a reasonable cost. This 10″ free air subwoofer is a low-cost, high-power bass driver that is easy to mount. It has a 1,500 watt maximum power rating, which is sure to loosen a few bolts. It has a durable polypropylene cone that is contained inside a flexible foam surround for efficiency and longevity. It has strong voice coils that can endure high temperatures and is housed in a solid die-cast frame. All of this is topped off with a three-year warranty for added assurance.
This speaker, however, can become muddy and boomy without a specialized enclosure. This is crucial in free-air settings, since you’ll need a tight-sounding subwoofer to compensate for the absence of enclosure.
- 800 WATT POWER: This 8in car subwoofer has a power of 400 Watt RMS to 800 Watt peak that will produce high sound resonance. It also has a spring...
- UNMATCHED PERFORMANCE: Built with 40 oz. magnet that will enhance car stereo or radio by producing a powerful audio and unmatched performance. It...
- DUAL VOICE COIL: The speaker subwoofer comes with a dual 4 Ohm impedance that can be wired as 4 or 8 Ohm. The 1.5" 4-layer voice coil can resist...
The Pyle PLPW8D power series subwoofer offers your audio solution if you want to add some serious heart-pounding bass. This tough subwoofer improves the quality of your sound system and brings your entertainment system to life. It’s a good product, and all you need to operate it is some solid equipment and a nice tune. So, whether you’re wanting to modify the audio system in your boat, car, or RV, PLPW8D has you covered.
The Pyle PLPW8D has a 40 oz. magnet that allows it to deliver robust audio to complement your car stereo. It also boasts an 89dB SPL (sensitivity) for superb clarity and a dual 4-Ohm impedance that can be wired as either 4 or 8 Ohm. For tremendous sound resonance, this 8-inch subwoofer is rated at 400 watts RMS and 800 watts maximum power.
For enhanced durability, the PLPW8D comes with a specially treated foam surround. Furthermore, it is totally built of non-fatiguing suspension to ensure the safety of other equipment. The 1.5-inch subwoofer also has a black steel basket, a non-pressed paper cone, and a black steel basket “For a longer life duration, choose a 4-layer voice coil that resists corrosion.
This best free air 8 subwoofer is straightforward to install and will fit most automobile audio systems as well as most boat audio systems. It also has an 8.2 inch diameter and comes with all of the essential wires, a user handbook, and an installation pattern. Furthermore, this subwoofer features spring-loaded push-down connectors that aid to improve sound quality.
This better motor design allows you to get the most out of your audio while also extending the life of your subwoofer. The sound is really clear, and it has a lot more punch than other subwoofers in this price range. They may not be able to handle large volumes well, but they will provide you with the low-end sound you desire.
Skar Audio VD-8 D2 8″ 400W RMS Dual 2Ω VD Series Subwoofer
- 8-Inch Dual 2 ohm Shallow Mount Subwoofer
- Peak Power: 600 Watts | RMS Power: 400 Watts
- Shallow Mount Design - Mounting Depth: 3.94"
The Skar Audio VD-8 D2 Shallow-Mount Car Subwoofer produces a lot of bass. A 2-inch high-temperature copper voice coil, a competition-grade cone encased by high-strength foam, an Xmax of 10.25 mm, and a 2-layer Conex spider are all included. It has a peak output of 600 watts and an RMS power of 400 watts.
It has a frequency response of 32 to 375 Hz and a sensitivity of 83.2 decibels. Because 8 free air subwoofer requires 3.94 inches to mount, it may not be as tiny as you’d want for the space you’ve planned. This subwoofer comes with a two-year limited guarantee from Skar.
Free Air Subwoofers Buyer’s Guide
We’ll examine what our sound professionals advise you to think about while choosing the best free-air subwoofers in the sections below.
As always, you need to be quite careful when choosing the size of the subwoofer. As they are likely to have deeper bass and a wider frequency range, subwoofers of a larger size will be considerably better for playing in open areas and huge rooms. You should think about this if you’re hosting a big gathering or a little celebration.
But, you can use a smaller sub if the event or automobile audio is quite tiny. Generally speaking, when it comes to size, there is no one size fits all solution for selecting the ideal subwoofer. What you want and the situation itself will determine the best course of action.
For placement, size also matters. You know, a large object might not fit in your automobile trunk very nicely.
This subwoofer statistic, expressed in Watts, largely reveals its sonic capability. You’ll typically see things like a peak strength of 1,000 W to 2,000 W in small subwoofers because they typically don’t have as much power. But the larger ones may provide peak power of up to 3,000 W and 4,000 W.
Subs can occasionally rise even farther, but this is extremely uncommon. Naturally, a more powerful sub can produce greater bass on a variety of levels. You can rely on it to function admirably whether the bass is high or low.
What you want will determine which subwoofer is ideal for you, just like with size. For example, less bass is needed when creating something for automobile audio. But if you want something for a bigger room, you’ll need better bass, which calls for a more powerful sub.
The sound quality of your free-air subwoofer is absolutely crucial, so pay attention to it. Your sound arrangement includes subs, so you must make sure they produce the ideal sound you require.
Indicators of sound quality are few and far between. The easiest way to manage this measure for most people is to listen to the free air subwoofer first. But you can also pay attention to where it appears and how often. For that clear audio to come through, some subs will need to be strategically placed. Take note of the manufacturer’s requirements and advice as well.
Fair enough, it’s important to point out that not every subwoofer requires an amplifier. The ones with amps, however, typically perform significantly better in terms of sound projection.
You must be aware of the amp’s capabilities if you choose a sub with an amplifier. You can effectively project the sound to the desired level with a powerful enough amp.
Just keep in mind that not every sub has an amplifier. If a choice you like has an amp, make sure the amp can project a pleasant sound if it does.
It will be considerably simpler to regulate the various components of a mix if each sub has a diverse frequency range. The auditory range of the majority of humans is 20 Hz to 20 kHz.
There are various ranges available for subwoofers. Sub-bass (20 Hz – 60 Hz), bass (61 Hz – 250 Hz), mid-level (251 Hz – 500 Hz), midrange (500 Hz – 2 kHz), high mids (2 kHz – 6 kHz), and highs are among them (6 kHz to 20 kHz).
You can examine the frequency range of the subwoofer to see whether it will work well for you based on the sound you intend to project.
A subwoofer’s impedance is determined by how resistive its voice coils are. In ohms [1,] it is measured. It will be simpler for an amp to send power to a subwoofer if its impedance is lower. It will be simpler for an amp to send power to a subwoofer if its impedance is lower.
You have a difficulty when the amp’s output connects to a low-impedance subwoofer. The sub will strive to produce more energy than it can need, which will cause it to overheat. Your sub will shut off if it is built to cut out when it becomes too hot. It might sustain damage if it isn’t.
So, be sure to check the sub’s energy as well as its impedance, if it has one.
Material and Durability
Last but not least, you must make sure that your free air subwoofer is sturdy. This is a result of the construction and design materials employed. Subwoofers will frequently be used at events and outdoors by a large number of people. You need something that can withstand harsh situations and yet function.
The subwoofer’s material may in some situations also affect how well its sound quality and bass are audible. The bass is punchier and more gripping when the sub is designed properly. You want something with a sturdy build if you want to obtain the best bass because bass is a picky sound.
Moreover, some goods feature a rubber surround that might aid in sound amplification. Check out a rubber surround in the material area if you want because it’s a wonderful addition. But, it’s crucial to check that your subwoofer is sturdy and long-lasting enough to withstand some challenging circumstances.
Frequently Asked Questions
What Is a Free Air Subwoofer?
Although a free-air subwoofer is the most basic subwoofer installation option, it does necessitate specially built subwoofers. Free air subwoofers don’t need a mounting box to function properly. Subwoofers are commonly mounted in the rear deck or affixed to a board put between the backseats of a car and the trunk in a free-air system.
This board creates an airtight seal, effectively enclosing the entire trunk – this is known as infinite baffle (IB) design (more on that later). However, it should be remembered that employing a free-air subwoofer may degrade sound quality to some extent. A subwoofer put in a well-designed enclosure will sound far better than one mounted in the open air. Furthermore, whatever you put in the trunk may hinder the sub(s) from sounding as well as they could, which can be inconvenient for normal car use.
When you’re mounting a sub or a couple of subs on your rear deck or behind the backseats, keep this in mind. It’s highly advised that you apply a sound deadening substance like Dynamat or Hushmat in the trunk to improve sound quality.
What is an infinite baffle subwoofer?
The infinite baffle subwoofer can be a closed or sealed box with the goal of smothering the loudspeaker’s rear sound waves.
What kind of features should these best free air subwoofers for a quality audio system?
These best freeair subwoofers should have the following features to get the best sound quality: reinforced rear deck, heavy duty steel basket foam surround for amazing sound quality, pressed paper cone (paper cone), punchy bass, more than enough trunk space, rubber surround, great bass without an enclosure, mica injected glass fiber foam surround steel basket, dual voice coil, open air setup, free air applications, good handle on low frequencies.