How to Choose a Subwoofer
Size, Voice Coils and Enclosures – What You Need to Know
Adding one or more subwoofers to a car audio system creates an exceptional listening experience. This guide covers the choices available for your vehicle.
Adding one or more subwoofers to a car audio system creates an exceptional listening experience. This guide covers the choices available for your vehicle.
What Does A Subwoofer Do?
A subwoofer is a critical part of any audio system. Its sole purpose is to produce low frequencies in music and video soundtracks. Without a subwoofer, this part of the music is never heard.
• How A Subwoofer Works – Simply put, subwoofers move air. The subwoofer’s cone is large and has more excursion (back and forth movement) compared to other speakers so it moves more air. The subwoofer experience is not about being "loud." Rather it is about moving enough air to produce low frequencies so that listeners can hear and ‘feel’ the complete sound experience.
• Subwoofer Enclosure - Subwoofer drivers require a box called an enclosure. Enclosures are needed because subwoofers require the ‘spring’ of air pressure trapped inside the enclosure to effectively create sound energy much the same way the pressure of a full balloon provides a jolt of energy when it pops. Energy stored as air pressure in the enclosure allows more tactile low frequency sound output. The enclosure also separates the air movement from the front and back of the cone, to prevent the air from canceling out the acoustic energy resulting from movement of the cone. Without the enclosure, that cancellation of energy would greatly reduce sound output.
• How A Subwoofer Works – Simply put, subwoofers move air. The subwoofer’s cone is large and has more excursion (back and forth movement) compared to other speakers so it moves more air. The subwoofer experience is not about being "loud." Rather it is about moving enough air to produce low frequencies so that listeners can hear and ‘feel’ the complete sound experience.
• Subwoofer Enclosure - Subwoofer drivers require a box called an enclosure. Enclosures are needed because subwoofers require the ‘spring’ of air pressure trapped inside the enclosure to effectively create sound energy much the same way the pressure of a full balloon provides a jolt of energy when it pops. Energy stored as air pressure in the enclosure allows more tactile low frequency sound output. The enclosure also separates the air movement from the front and back of the cone, to prevent the air from canceling out the acoustic energy resulting from movement of the cone. Without the enclosure, that cancellation of energy would greatly reduce sound output.
Subwoofer Choices
Here are different types of subwoofers available for car audio systems:
• Powered Subwoofers - Also called amplified subwoofers, these models include a subwoofer driver, the enclosure, and a built-in amplifier. The built-in amplifier is matched to the subwoofer, and the enclosure and internal volume are optimized for the subwoofer driver’s performance characteristics. Powered subwoofers typically accept speaker level or preamp level RCA inputs, making them a great addition to an OEM or aftermarket audio system. Powered subwoofers typically include all the necessary mounting hardware, but may require power wiring and audio signal inputs to complete the installation.
• Loaded Enclosures - This type has one or more subwoofer drivers wired and installed in a finished enclosure. The loaded enclosure is typically constructed of medium density fiberboard (MDF) or particleboard and finished with durable carpeting or rugged, textured paint. These units are wired with a convenient binding post or terminal cup to attach wiring from an amplifier. All that is needed is a suitable amplifier (sold and installed separately) to power the loaded enclosure, along with power wiring and audio inputs. Loaded enclosures are a great solution for robust bass response and are often available in dual or triple subwoofer systems.
• Raw Subwoofer Drivers - Raw drivers are individual speakers (including subwoofers) with no enclosure or power amplifier included. Generally between 8”-18” in diameter, raw subwoofer drivers do not provide a complete package for delivering bass and need an optimized enclosure and amplifier power. Manufacturers typically supply the recommended type of enclosure and how much power is needed in the specifications.
o For additional information about matching subwoofers with amplifiers, review the Consumer Buyer’s Guide Matching Subwoofers and Amplifiers at Amazon’s Car Electronics Resource Center.
o For specific information about recommended enclosure sizes for a specific subwoofer driver, review the manufacturer’s website or product specifications provided on Amazon.com.
• Powered Subwoofers - Also called amplified subwoofers, these models include a subwoofer driver, the enclosure, and a built-in amplifier. The built-in amplifier is matched to the subwoofer, and the enclosure and internal volume are optimized for the subwoofer driver’s performance characteristics. Powered subwoofers typically accept speaker level or preamp level RCA inputs, making them a great addition to an OEM or aftermarket audio system. Powered subwoofers typically include all the necessary mounting hardware, but may require power wiring and audio signal inputs to complete the installation.
• Loaded Enclosures - This type has one or more subwoofer drivers wired and installed in a finished enclosure. The loaded enclosure is typically constructed of medium density fiberboard (MDF) or particleboard and finished with durable carpeting or rugged, textured paint. These units are wired with a convenient binding post or terminal cup to attach wiring from an amplifier. All that is needed is a suitable amplifier (sold and installed separately) to power the loaded enclosure, along with power wiring and audio inputs. Loaded enclosures are a great solution for robust bass response and are often available in dual or triple subwoofer systems.
• Raw Subwoofer Drivers - Raw drivers are individual speakers (including subwoofers) with no enclosure or power amplifier included. Generally between 8”-18” in diameter, raw subwoofer drivers do not provide a complete package for delivering bass and need an optimized enclosure and amplifier power. Manufacturers typically supply the recommended type of enclosure and how much power is needed in the specifications.
o For additional information about matching subwoofers with amplifiers, review the Consumer Buyer’s Guide Matching Subwoofers and Amplifiers at Amazon’s Car Electronics Resource Center.
o For specific information about recommended enclosure sizes for a specific subwoofer driver, review the manufacturer’s website or product specifications provided on Amazon.com.
Subwoofer Driver Specifications to Consider
Subwoofer driver specifications include voice coil configuration (single or dual voice coils), power handling, and cone size (diameter and mounting depth). The type of enclosure (sealed or vented), airspace volume requirement of the recommended enclosure, and how it fits in the vehicle must also be considered.
• Diameter and Depth - Subwoofers generally range between 8”- 18” in diameter. Larger diameter does not always mean higher power handling or higher power requirements. In general, the larger the diameter, the more mounting depth is required for a given subwoofer. One benefit is larger cones radiate more energy into the listening space than a smaller cone if both are delivered the same power. The trade-off is that larger diameter subwoofer cones typically require a larger enclosure to achieve optimum performance when compared to a smaller subwoofer. ‘Shallow’ or ‘thin’ subwoofers have reduced mounting depth and work well in locations such as under seats or behind truck bench seats. Always ensure the subwoofer’s mounting depth does not exceed the available depth where the enclosure is to be installed. In many installations, two small diameter subwoofers may fit and perform better than one large diameter subwoofer, if adequate space is not available for the larger subwoofer.
• Ohms and Voice Coil Configurations - Subwoofers have single voice coils (SVC) or dual voice coils (DVC). The voice coil converts the electrical power from the amplifier into energy that attracts to (or repels from) the subwoofer’s magnet. This is how the subwoofer’s cone moves.
o Nominal Impedance (Ohms) - The rating for a voice coil is called the nominal impedance (rated in units of ohms). There are different nominal impedance values of voice coils (example: single 2 ohm, single 4 ohm, single 8 ohm, dual 2 ohm, and dual 4 ohm ). This nominal impedance is representative of the ‘load’ that the subwoofer places on the amplifier to do the work of moving the subwoofer to replicate low frequencies. Lower nominal impedance values cause the amplifier to output more power and consume more current from the electrical system. By choosing the appropriate nominal impedance voice coils and considering the amplifier to which the subwoofer(s) connect, these variables allow the optimum ‘load’ for an amplifier. Subwoofers always perform best when the amplifier load is optimized to comfortably power them without excess heat on the amplifier or current drawn from the vehicle electrical system. Optimizing the amplifier load simply means higher reliability of the whole audio system.
o Wiring - Wiring configurations include series, parallel, or series-parallel with multiple voice coils. Each wiring design allows for a different configuration of subwoofer(s) to amplifier(s).
•Recommended Practice - A general rule of thumb is to choose voice coil configurations that load amplifiers at 4 ohms (2 ohms on amplifiers that can support it). This allows the amplifier to power the subwoofer(s) continuously with no overheating or overloading problems.
o For additional information about matching subwoofers with amplifiers, review the Consumer Buyer’s Guide Matching Subwoofers and Amplifiers and the Subwoofer Installation Guide at Amazon’s Car Electronics Resource Library. Many manufacturers’ websites provide wiring information for multiple subwoofers and voice coils.
• Subwoofer Enclosures - Most subwoofers in vehicle audio systems use either a sealed enclosure or vented (or ported) enclosure. Deciding between the two depends on the subwoofer driver, vehicle, and listener’s tastes. As the first step, refer to the manufacturer’s recommendations to determine if a sealed or vented enclosure is recommended for the subwoofer driver.
o Sealed Enclosures - A sealed enclosure is the easiest to design and build, and it offers many benefits:
• Sealed enclosures, also called ‘air suspension’ enclosures because the air trapped inside the enclosure assists and counter balances the speaker’s movement like a spring.
• Sealed enclosures are known for their ‘tight’ sound and have fast transient response characteristics. A fast transient response avoids a condition called ‘one note bass’ in which the low frequency reacts at a slower pace than the rest of the music and seems out of step (in arrival time) to the ear.
• Sealed enclosures also have excellent upper bass to lower midrange transition. This means the subwoofer’s output blends and balances with other speakers in the audio system.
• Sealed enclosures are a great choice for performance across a wide variety of music.
• Pre-constructed, empty sealed enclosures like those sold at Amazon.com provide an excellent solution for a ready-made enclosure.
o Vented Enclosures - A vented enclosure has a vent to move air out of the enclosure at a specific frequency. This increases the output of the subwoofer driver. Also known as ‘ported’ enclosures or ‘bass-reflex’ enclosures, vented enclosures provide deeper bass than a sealed enclosure but are less forgiving on the internal airspace variations. Advantages and disadvantages include:
• Vented enclosures take advantage of the rear wave energy of the speaker. The addition of a vent (port) creates an acoustic resonator that tunes or breathes at a unique pitch. The energy from the rear of the speaker is used to restore it to its original center position, like a spring. In vented enclosures, this rear wave energy is coupled with the energy from the front of the speaker through a tuned opening (the vent) to reinforce bass output. The advantage is louder bass at the tuned frequency range when compared to a sealed enclosure.
• There is a delicate relationship between the enclosure size (internal air volume), vent size (both the opening and length) and the speaker’s parameters. This is why the manufacturer’s internal airspace requirements are so important. The vent tuning frequency is the point at which a vented enclosure handles the most power, but below that frequency, power handling is poor. If the volume or vent dimensions are off, the subwoofer can be damaged by excessive, uncontrolled cone movement below the incorrectly tuned vent frequency.
• Power handling below the vent tuning frequency is poor and produces significant distortion. Active subsonic filtering avoids this issue by sharply filtering frequencies below 20Hz. Many subwoofer amplifiers feature subsonic or infrasonic filtering for this purpose. It does not limit the range of the subwoofer because the frequencies below 20Hz are inaudible to the human ear.
• Diameter and Depth - Subwoofers generally range between 8”- 18” in diameter. Larger diameter does not always mean higher power handling or higher power requirements. In general, the larger the diameter, the more mounting depth is required for a given subwoofer. One benefit is larger cones radiate more energy into the listening space than a smaller cone if both are delivered the same power. The trade-off is that larger diameter subwoofer cones typically require a larger enclosure to achieve optimum performance when compared to a smaller subwoofer. ‘Shallow’ or ‘thin’ subwoofers have reduced mounting depth and work well in locations such as under seats or behind truck bench seats. Always ensure the subwoofer’s mounting depth does not exceed the available depth where the enclosure is to be installed. In many installations, two small diameter subwoofers may fit and perform better than one large diameter subwoofer, if adequate space is not available for the larger subwoofer.
• Ohms and Voice Coil Configurations - Subwoofers have single voice coils (SVC) or dual voice coils (DVC). The voice coil converts the electrical power from the amplifier into energy that attracts to (or repels from) the subwoofer’s magnet. This is how the subwoofer’s cone moves.
o Nominal Impedance (Ohms) - The rating for a voice coil is called the nominal impedance (rated in units of ohms). There are different nominal impedance values of voice coils (example: single 2 ohm, single 4 ohm, single 8 ohm, dual 2 ohm, and dual 4 ohm ). This nominal impedance is representative of the ‘load’ that the subwoofer places on the amplifier to do the work of moving the subwoofer to replicate low frequencies. Lower nominal impedance values cause the amplifier to output more power and consume more current from the electrical system. By choosing the appropriate nominal impedance voice coils and considering the amplifier to which the subwoofer(s) connect, these variables allow the optimum ‘load’ for an amplifier. Subwoofers always perform best when the amplifier load is optimized to comfortably power them without excess heat on the amplifier or current drawn from the vehicle electrical system. Optimizing the amplifier load simply means higher reliability of the whole audio system.
o Wiring - Wiring configurations include series, parallel, or series-parallel with multiple voice coils. Each wiring design allows for a different configuration of subwoofer(s) to amplifier(s).
•Recommended Practice - A general rule of thumb is to choose voice coil configurations that load amplifiers at 4 ohms (2 ohms on amplifiers that can support it). This allows the amplifier to power the subwoofer(s) continuously with no overheating or overloading problems.
o For additional information about matching subwoofers with amplifiers, review the Consumer Buyer’s Guide Matching Subwoofers and Amplifiers and the Subwoofer Installation Guide at Amazon’s Car Electronics Resource Library. Many manufacturers’ websites provide wiring information for multiple subwoofers and voice coils.
• Subwoofer Enclosures - Most subwoofers in vehicle audio systems use either a sealed enclosure or vented (or ported) enclosure. Deciding between the two depends on the subwoofer driver, vehicle, and listener’s tastes. As the first step, refer to the manufacturer’s recommendations to determine if a sealed or vented enclosure is recommended for the subwoofer driver.
o Sealed Enclosures - A sealed enclosure is the easiest to design and build, and it offers many benefits:
• Sealed enclosures, also called ‘air suspension’ enclosures because the air trapped inside the enclosure assists and counter balances the speaker’s movement like a spring.
• Sealed enclosures are known for their ‘tight’ sound and have fast transient response characteristics. A fast transient response avoids a condition called ‘one note bass’ in which the low frequency reacts at a slower pace than the rest of the music and seems out of step (in arrival time) to the ear.
• Sealed enclosures also have excellent upper bass to lower midrange transition. This means the subwoofer’s output blends and balances with other speakers in the audio system.
• Sealed enclosures are a great choice for performance across a wide variety of music.
• Pre-constructed, empty sealed enclosures like those sold at Amazon.com provide an excellent solution for a ready-made enclosure.
o Vented Enclosures - A vented enclosure has a vent to move air out of the enclosure at a specific frequency. This increases the output of the subwoofer driver. Also known as ‘ported’ enclosures or ‘bass-reflex’ enclosures, vented enclosures provide deeper bass than a sealed enclosure but are less forgiving on the internal airspace variations. Advantages and disadvantages include:
• Vented enclosures take advantage of the rear wave energy of the speaker. The addition of a vent (port) creates an acoustic resonator that tunes or breathes at a unique pitch. The energy from the rear of the speaker is used to restore it to its original center position, like a spring. In vented enclosures, this rear wave energy is coupled with the energy from the front of the speaker through a tuned opening (the vent) to reinforce bass output. The advantage is louder bass at the tuned frequency range when compared to a sealed enclosure.
• There is a delicate relationship between the enclosure size (internal air volume), vent size (both the opening and length) and the speaker’s parameters. This is why the manufacturer’s internal airspace requirements are so important. The vent tuning frequency is the point at which a vented enclosure handles the most power, but below that frequency, power handling is poor. If the volume or vent dimensions are off, the subwoofer can be damaged by excessive, uncontrolled cone movement below the incorrectly tuned vent frequency.
• Power handling below the vent tuning frequency is poor and produces significant distortion. Active subsonic filtering avoids this issue by sharply filtering frequencies below 20Hz. Many subwoofer amplifiers feature subsonic or infrasonic filtering for this purpose. It does not limit the range of the subwoofer because the frequencies below 20Hz are inaudible to the human ear.
Which Enclosure Is Right for Your Subwoofer?
Many speaker manufacturers recommend a particular enclosure for a specific subwoofer.
• Manufacturer Recommendations– Nearly all subwoofer manufacturers provide precise enclosure recommendations for the subwoofer driver. MDF material thickness is specified (usually 3/4” or thicker). Manufacturers publish volumes of internal – not just external - airspace and vent dimensions (where applicable) to ensure consumers achieve the best possible results. This information is widely available in product information, owner’s manuals, application guides, and manufacturer websites. Use these volume recommendations to select an empty enclosure on Amazon.com or to determine the appropriate size of a custom-built enclosure.
• Enclosure Dimensions and Airspace Availability- The internal airspace requirement of the enclosure is also important. If you want to install a 12” subwoofer but the internal enclosure airspace space only supports a single 10” woofer, use the single 10” rather than squeezing too large of a subwoofer into the enclosure. In the end, the subwoofer with the best match of airspace to its optimum enclosure size will perform better.
• Power Handling vs Power Applied – Always match the subwoofer’s RMS power handling with the RMS power output of the amplifier to ensure the subwoofer has enough power to ‘move the air’ and function in its specific enclosure. Sealed enclosures require slightly more power than a vented enclosure to deliver the same sound pressure levels (SPL) because of the tighter air spring effect (all other conditions being equal). For additional information about matching subwoofers with amplifiers, review the buying guide Matching Subwoofers and Amplifiers at Amazon’s Car Electronics Guide Library.
• Manufacturer Recommendations– Nearly all subwoofer manufacturers provide precise enclosure recommendations for the subwoofer driver. MDF material thickness is specified (usually 3/4” or thicker). Manufacturers publish volumes of internal – not just external - airspace and vent dimensions (where applicable) to ensure consumers achieve the best possible results. This information is widely available in product information, owner’s manuals, application guides, and manufacturer websites. Use these volume recommendations to select an empty enclosure on Amazon.com or to determine the appropriate size of a custom-built enclosure.
• Enclosure Dimensions and Airspace Availability- The internal airspace requirement of the enclosure is also important. If you want to install a 12” subwoofer but the internal enclosure airspace space only supports a single 10” woofer, use the single 10” rather than squeezing too large of a subwoofer into the enclosure. In the end, the subwoofer with the best match of airspace to its optimum enclosure size will perform better.
• Power Handling vs Power Applied – Always match the subwoofer’s RMS power handling with the RMS power output of the amplifier to ensure the subwoofer has enough power to ‘move the air’ and function in its specific enclosure. Sealed enclosures require slightly more power than a vented enclosure to deliver the same sound pressure levels (SPL) because of the tighter air spring effect (all other conditions being equal). For additional information about matching subwoofers with amplifiers, review the buying guide Matching Subwoofers and Amplifiers at Amazon’s Car Electronics Guide Library.
Professional Subwoofer Enclosure Construction
For a truly custom fit subwoofer enclosure, visit an installation professional at an independent car audio retailer. Many welcome the opportunity to install products purchased at Amazon.com and have wood and fabrication facilities to skillfully construct a subwoofer enclosure that is ideal for your vehicle.
When to Consider Professional Installation
Vehicles are complex machines. Before attempting any DIY installation, assess your comfort level with the installation of electronics and mechanics of your vehicle.
Consider a professional installer if:
1. You are not comfortable disassembling vehicle interior panels.
2. You do not have a suitable work area available.
3. You do not have the recommended tools for the job.
4. You do not have the necessary installation accessories specific to your vehicle year/make/model.
Many independent retail installation shops welcome jobs with products purchased on Amazon.com. Professional installers can also provide many of the installation accessories you need for jobs that are covered in this guide. Always look for a Mobile Electronics Certified Professional (MECP) installation technician to handle your most challenging installation needs.
Want to purchase installation now? Find an InstallerNet card on Amazon.com that corresponds to your job type.
Consider a professional installer if:
1. You are not comfortable disassembling vehicle interior panels.
2. You do not have a suitable work area available.
3. You do not have the recommended tools for the job.
4. You do not have the necessary installation accessories specific to your vehicle year/make/model.
Many independent retail installation shops welcome jobs with products purchased on Amazon.com. Professional installers can also provide many of the installation accessories you need for jobs that are covered in this guide. Always look for a Mobile Electronics Certified Professional (MECP) installation technician to handle your most challenging installation needs.
Want to purchase installation now? Find an InstallerNet card on Amazon.com that corresponds to your job type.
THANKS: amazon.com