Matching Subwoofers and Amplifiers
Amplify Your Car Audio Experience.
Important factors to consider when matching subwoofers and amplifiers.
Important factors to consider when matching subwoofers and amplifiers.
Why Do Subwoofers Need An Amplifier?
The job of a subwoofer is to provide low frequency performance to an audio system. It accomplishes this task by moving air, but subwoofer drivers are passive devices (non-powered). Thus, subwoofers require an energy source, in the form of wattage from an amplifier, to move the subwoofer cone effectively.
Matching Subwoofer Power Handling with Amplifier Power (CEA-2031 and CEA-2006-B)
To make selecting and matching car audio equipment easier for consumers, the Consumer Electronics Association (CEA) creates standards for car audio product specifications.
• CEA-2031 – This standard defines power handling for car audio speakers, including subwoofers. The ratings consider continuous power handling rather than ‘peak’ or ‘max’ power and are measured in watts RMS (Root Mean Square). These ratings are the most accurate measure of a speaker’s performance capability. Speakers that meet this standard publish their CEA-2031 ratings.
• CEA 2006-B – This standard defines power output for car audio amplifiers (and in-dash receivers) that have power output greater than 5 watts. CEA-2006-B provides an RMS power output rating (in watts) derived from a standardized battery voltage of 14.4, replicating vehicle voltage while the engine is running. Amplifiers and in-dash receivers that meet the standard publish their CEA-2006-B ratings, making the stated ‘watts’ of different products comparable without confusion to the consumer.
CEA-2006-B and CEA-2031 provide ratings that make matching amplifiers with subwoofers easy. For example, a subwoofer that is CEA-2031 rated to handle 200 watts RMS will match an amplifier that is CEA-2006-B rated to deliver 200 watts RMS of output. Matched ratings will result in better system performance than mismatched power output and power handling. Match the RMS output power of each amplifier channel to the subwoofer in the range +/- 25%.
If there are no CEA ratings for amplifiers and speakers, consumers should compare only RMS power ratings. Do not use ‘max’ or ‘peak’ power specifications to match speakers with an amplifier.
• CEA-2031 – This standard defines power handling for car audio speakers, including subwoofers. The ratings consider continuous power handling rather than ‘peak’ or ‘max’ power and are measured in watts RMS (Root Mean Square). These ratings are the most accurate measure of a speaker’s performance capability. Speakers that meet this standard publish their CEA-2031 ratings.
• CEA 2006-B – This standard defines power output for car audio amplifiers (and in-dash receivers) that have power output greater than 5 watts. CEA-2006-B provides an RMS power output rating (in watts) derived from a standardized battery voltage of 14.4, replicating vehicle voltage while the engine is running. Amplifiers and in-dash receivers that meet the standard publish their CEA-2006-B ratings, making the stated ‘watts’ of different products comparable without confusion to the consumer.
CEA-2006-B and CEA-2031 provide ratings that make matching amplifiers with subwoofers easy. For example, a subwoofer that is CEA-2031 rated to handle 200 watts RMS will match an amplifier that is CEA-2006-B rated to deliver 200 watts RMS of output. Matched ratings will result in better system performance than mismatched power output and power handling. Match the RMS output power of each amplifier channel to the subwoofer in the range +/- 25%.
If there are no CEA ratings for amplifiers and speakers, consumers should compare only RMS power ratings. Do not use ‘max’ or ‘peak’ power specifications to match speakers with an amplifier.
Mono or Stereo Channels?
In most cases, mono amplifiers are specifically designed for subwoofers. Stereo (2-channel) amplifiers offer more flexibility, and multi-channel amplifiers can power entire systems. Be sure to check out the How to Choose Amplifiers Buyer’s Guide for additional information on these choices.
• Mono Amplifiers – Mono amplifiers are ideal for subwoofers because there is a single (mono) output channel to connect the subwoofer. Many mono subwoofer amplifiers are Class D, which are designed for power efficiency, and often have low pass crossovers and built-in bass boost. The bass boost feature offers adjustable increases in power output at a specific low frequency, which increases bass output at those frequencies.
• Stereo (2-channel) Amplifiers – The advantage of using a 2-channel amplifier, instead of a mono amplifier, is greater flexibility with subwoofers and voice coil wiring configurations. 2-channel amplifiers can drive one subwoofer per channel or together in a bridged channel configuration. They can also be used to power speakers in other frequency ranges as the car audio system expands. Bridging combines the power of two channels to create a single, more powerful channel that is ideal for subwoofers. Most 2-channel amps have built-in selectable high-pass and low-pass crossovers, and many also have a bass boost feature.
• Multi-Channel ‘System’ Amplifiers – Amplifiers with 3 or more channels are called multi-channel amplifiers. These use a single amplifier chassis to power multiple speakers, often in different frequency ranges, and provide a complete ‘system amplifier’ approach. Multi-channel amps have built-in internal crossovers (both high and low pass) that route signals to the appropriate speakers in the system.
Many manufacturers create multi-channel amps as a complete system by using Class A/B topology on ‘front’ and/or ‘rear’ channels of the amp and Class D topology on a ‘subwoofer’ channel. This maximizes the performance of power output and sound quality. Multi-channel system amplifiers are also easier to install than multiple amplifiers because no additional power distribution blocks or other power wiring splitters are needed.
• Mono Amplifiers – Mono amplifiers are ideal for subwoofers because there is a single (mono) output channel to connect the subwoofer. Many mono subwoofer amplifiers are Class D, which are designed for power efficiency, and often have low pass crossovers and built-in bass boost. The bass boost feature offers adjustable increases in power output at a specific low frequency, which increases bass output at those frequencies.
• Stereo (2-channel) Amplifiers – The advantage of using a 2-channel amplifier, instead of a mono amplifier, is greater flexibility with subwoofers and voice coil wiring configurations. 2-channel amplifiers can drive one subwoofer per channel or together in a bridged channel configuration. They can also be used to power speakers in other frequency ranges as the car audio system expands. Bridging combines the power of two channels to create a single, more powerful channel that is ideal for subwoofers. Most 2-channel amps have built-in selectable high-pass and low-pass crossovers, and many also have a bass boost feature.
• Multi-Channel ‘System’ Amplifiers – Amplifiers with 3 or more channels are called multi-channel amplifiers. These use a single amplifier chassis to power multiple speakers, often in different frequency ranges, and provide a complete ‘system amplifier’ approach. Multi-channel amps have built-in internal crossovers (both high and low pass) that route signals to the appropriate speakers in the system.
Many manufacturers create multi-channel amps as a complete system by using Class A/B topology on ‘front’ and/or ‘rear’ channels of the amp and Class D topology on a ‘subwoofer’ channel. This maximizes the performance of power output and sound quality. Multi-channel system amplifiers are also easier to install than multiple amplifiers because no additional power distribution blocks or other power wiring splitters are needed.
Multiple Subwoofers – Add One Amp or More?
When installing multiple subwoofer drivers, keep in mind these important amplifier considerations.
• Shared Airspace in the Enclosure – In multiple subwoofer systems, where individual subwoofer drivers share a common airspace inside an enclosure, a mono channel amplifier is recommended (or a bridged 2-channel amplifier). This ensures that all subwoofers are driven from the same output and move in and out identically. If using separate channels on each separate subwoofers in the same enclosure, make sure there is a dividing wall between each chamber so that each subwoofer’s airspace is unaffected by the other subwoofer(s). Observing this tip ensures that no subwoofer prematurely fails from overdriving or mismatched channel levels.
• Voice Coil Configurations – Before installing multiple subwoofers, consider how the voice coils will be wired to ensure the nominal impedance load on the amplifier is not below the published stable ohm load. Most amplifiers perform well (with low heat and high reliability) when connected to a 4 or 2-ohm load of subwoofers. Subwoofer manufacturer’s websites provide subwoofer-wiring calculators to assist in determining the correct subwoofer voice coil configuration (SVC or DVC) and what nominal impedance is best. Check out the Installing Subwoofers Installation Guide in the Car Electronics Resource Center for helpful hints and diagrams.
• Available Vehicle Power – Amplifiers consume energy from the vehicle electrical system to create output power for speakers. Each amplifier added to the system increases the vehicle electrical power required. Most healthy and functioning factory electrical systems with a standard alternator and standard sized battery can support up to 800 watts RMS with no issues. Adding batteries is not recommended because batteries only supply electrical power to amplifiers while the vehicle engine is off. Once the vehicle is started and the alternator begins charging, extra batteries become a drag on the electrical system. Consider what your vehicle’s electrical system can support and/or what alternator upgrade options are available before choosing multiple or high wattage amplifiers.
• Shared Airspace in the Enclosure – In multiple subwoofer systems, where individual subwoofer drivers share a common airspace inside an enclosure, a mono channel amplifier is recommended (or a bridged 2-channel amplifier). This ensures that all subwoofers are driven from the same output and move in and out identically. If using separate channels on each separate subwoofers in the same enclosure, make sure there is a dividing wall between each chamber so that each subwoofer’s airspace is unaffected by the other subwoofer(s). Observing this tip ensures that no subwoofer prematurely fails from overdriving or mismatched channel levels.
• Voice Coil Configurations – Before installing multiple subwoofers, consider how the voice coils will be wired to ensure the nominal impedance load on the amplifier is not below the published stable ohm load. Most amplifiers perform well (with low heat and high reliability) when connected to a 4 or 2-ohm load of subwoofers. Subwoofer manufacturer’s websites provide subwoofer-wiring calculators to assist in determining the correct subwoofer voice coil configuration (SVC or DVC) and what nominal impedance is best. Check out the Installing Subwoofers Installation Guide in the Car Electronics Resource Center for helpful hints and diagrams.
• Available Vehicle Power – Amplifiers consume energy from the vehicle electrical system to create output power for speakers. Each amplifier added to the system increases the vehicle electrical power required. Most healthy and functioning factory electrical systems with a standard alternator and standard sized battery can support up to 800 watts RMS with no issues. Adding batteries is not recommended because batteries only supply electrical power to amplifiers while the vehicle engine is off. Once the vehicle is started and the alternator begins charging, extra batteries become a drag on the electrical system. Consider what your vehicle’s electrical system can support and/or what alternator upgrade options are available before choosing multiple or high wattage amplifiers.
Specific Features and Benefits of Amplifiers
Amplifiers with specific features are ideal for subwoofers.
• Built-in Low Pass Crossover – A low pass crossover is a filter that prevents high frequencies from being sent to the subwoofer. Most amplifiers have built-in crossovers that are selectable between low or high pass. An upgraded feature is adjustable (also called ‘variable’) low pass frequency.
o If the receiver has SUB OUT - Many in-dash receivers with ‘SUB OUT’ preamp level outputs have internal low pass crossovers. If the amp does not have a built-in low pass crossover, the internal low pass crossover in the receiver can serve as the subwoofer signal’s filter. If the receiver and amplifier each have one built in, use only the low pass crossover on the amplifier to avoid distortion or frequency response anomalies where the low pass crossover point transitions to the higher frequency ranges covered by other speakers in the system.
• Subsonic Filter – Also called an infrasonic filter, this is a high pass crossover for frequencies below human hearing that a vehicle audio system cannot reproduce. Subsonic filters are built into many amplifiers and filter out frequencies below 20Hz. This keeps amplifier power reserved for frequencies the subwoofer can produce and will increase the overall longevity and reliability of the subwoofer system.
• Bass Boost – Bass boost offers adjustable increases of power delivered to a subwoofer at a specific frequency which adds bass response in the car. Some bass boost circuits allow adjustment to the boost frequency while others are fixed, often between 45Hz-55Hz. Many amplifiers offer a telephone jack style plug on the amplifier that connects to a cable and remote-mounted dash control knob. The control knob allows bass boost adjustment from the driver’s seat.
• Pass-through Preamp RCA Outputs – Pass-through outputs provide a secondary set of preamp RCA outputs (rather than inputs). These outputs connect additional amplifiers without having to use signal splitters on the main RCA input cable or run a second RCA audio cable from the in-dash receiver. Many pass-through outputs are buffered to maintain a high signal voltage, which rejects unwanted radiated noise in subsequent amplifiers.
• High Level Inputs (also called ‘Speaker Level Inputs’) – Amplifiers with high level inputs accept speaker wires as an audio input from a receiver, instead of preamp level RCA inputs. This feature is beneficial when adding an amplifier to a stereo. A Line Output Converter (LOC) is not necessary when the amplifier has high level inputs.
• Power Supply Regulation – Healthy vehicle electrical systems provide between 12 volts (with the engine off) and 14.4 volts or more (with the engine running). Many amplifier manufacturers use regulated power supplies on the power input stage to help the amplifier maintain stable internal voltage with those variables. Regulation produces more consistent output power for the speaker(s). The benefit of a regulated power supply design is that no matter the input voltage, the amplifier will always deliver its rated RMS power. This is especially important for subwoofers, which require the most power of any of the speakers in the vehicle’s audio system.
• Built-in Low Pass Crossover – A low pass crossover is a filter that prevents high frequencies from being sent to the subwoofer. Most amplifiers have built-in crossovers that are selectable between low or high pass. An upgraded feature is adjustable (also called ‘variable’) low pass frequency.
o If the receiver has SUB OUT - Many in-dash receivers with ‘SUB OUT’ preamp level outputs have internal low pass crossovers. If the amp does not have a built-in low pass crossover, the internal low pass crossover in the receiver can serve as the subwoofer signal’s filter. If the receiver and amplifier each have one built in, use only the low pass crossover on the amplifier to avoid distortion or frequency response anomalies where the low pass crossover point transitions to the higher frequency ranges covered by other speakers in the system.
• Subsonic Filter – Also called an infrasonic filter, this is a high pass crossover for frequencies below human hearing that a vehicle audio system cannot reproduce. Subsonic filters are built into many amplifiers and filter out frequencies below 20Hz. This keeps amplifier power reserved for frequencies the subwoofer can produce and will increase the overall longevity and reliability of the subwoofer system.
• Bass Boost – Bass boost offers adjustable increases of power delivered to a subwoofer at a specific frequency which adds bass response in the car. Some bass boost circuits allow adjustment to the boost frequency while others are fixed, often between 45Hz-55Hz. Many amplifiers offer a telephone jack style plug on the amplifier that connects to a cable and remote-mounted dash control knob. The control knob allows bass boost adjustment from the driver’s seat.
• Pass-through Preamp RCA Outputs – Pass-through outputs provide a secondary set of preamp RCA outputs (rather than inputs). These outputs connect additional amplifiers without having to use signal splitters on the main RCA input cable or run a second RCA audio cable from the in-dash receiver. Many pass-through outputs are buffered to maintain a high signal voltage, which rejects unwanted radiated noise in subsequent amplifiers.
• High Level Inputs (also called ‘Speaker Level Inputs’) – Amplifiers with high level inputs accept speaker wires as an audio input from a receiver, instead of preamp level RCA inputs. This feature is beneficial when adding an amplifier to a stereo. A Line Output Converter (LOC) is not necessary when the amplifier has high level inputs.
• Power Supply Regulation – Healthy vehicle electrical systems provide between 12 volts (with the engine off) and 14.4 volts or more (with the engine running). Many amplifier manufacturers use regulated power supplies on the power input stage to help the amplifier maintain stable internal voltage with those variables. Regulation produces more consistent output power for the speaker(s). The benefit of a regulated power supply design is that no matter the input voltage, the amplifier will always deliver its rated RMS power. This is especially important for subwoofers, which require the most power of any of the speakers in the vehicle’s audio system.
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.
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. 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.
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. 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