Simply put, an amplifier (amp) is a device for increasing the power of a signal. The “head” unit (such as a radio or CD player) in a car has limited power and typically does not have the power to operate additional or larger speakers. When adding aftermarket components, an amplifier is often necessary to provide additional output to the speakers and subwoofers. Basically the amplifier acts as the power source for the car sound system by modulating the power generated by the car battery to allow the speakers to reach their full potential. The “gain” of an amplifier is the ratio of output to input power or amplitude, and is usually measured in decibels (dB).
Because of the large amount of power required to drive subwoofers and produce the low frequency sound, car subwoofers must have at least one amplifier to provide enough power for the subwoofers to operate as designed. If space is a concern, powered subwoofers are available in which the enclosure has both an amplifier and a subwoofer. The performance capabilities of the amplifier and subwoofer must be matched to avoid damage to the system.
Class D Amplifiers
In simple terms, a Class D amplifier is an electronic amplifier where the power devices, usually MOSFETs, are operating as binary switches, being either fully on or fully off. The speed of the switches must be much higher than the desired frequencies of the input signal. The amplifier uses Pulse Width Modulation (PWM) to convert the input signal to a series of pulses, which in turn drive the power devices, which deliver a changing voltage into a fixed load such as a subwoofer. The high frequency switching produces undesirable frequencies which are removed by a low pass filter, leaving only those relevant to the input signal. Class D is sometimes misinterpreted as being synonymous with “digital,” but that is not the case. All Class D amplifiers are not digital, but the term is often used for Class D amplifiers with significant amounts of digital processing in them.
Class D amplifier are noted for their very high efficiency, so they are often used where a high level of power is required, such as driving large subwoofers. Practically, efficiencies of over 90% are achievable, thus reducing the amount of heat produced. Because of their efficiency, they require a smaller heat sink which reduces size and cost. Class D amplifiers are used in many applications, including powered subwoofers, powered speakers, mobile applications (to save battery power), and bass amplifiers. While early Class D amplifiers were used mainly for subwoofers, advances have produced high power, low distortion units covering the entire audio band.
A midrange driver is a speaker that produces sounds in between the low frequencies of a woofer and the high frequencies of a tweeter. Typically the frequency range is from about 300 to 5000 Hz. They are often used in three-way multi-driver speaker systems to complement the low frequency woofers and the high frequency tweeters. As it turns out, midrange drivers produce the most significant part of the sound spectrum, containing most of the fundamental sounds of musical instruments and the human voice. These are the sounds most familiar to the human ear. Mid-range speakers are often found in televisions, where talking is of paramount importance. Since these frequencies are so important, the human ear is readily able to detect any distortion or lack of clarity. A mid-range driver should be capable of low-distortion reproduction of sound with adequate volume. Fortunately, because the ear is so sensitive to these sounds the power needed to drive a midrange driver can be low. Mid-range drivers come in different types, but are usually cone types or, less commonly, dome types, or compression horn drivers. Typically the cone is made of paper, although a wide range of other materials is also used.
A complete discussion of MOSFET is quite complicated and involves some rather ugly mathematics, so we’ll stick to the essentials relevant to car audio. Basically, MOSFET is the acronym for a “metal oxide semiconductor field-effect transistor” designed to handle significant power levels. A MOSFET can be considered to be a voltage-controlled switch. They are typically used in Class D audio amplifiers where there is rapid switching off and on in response to the input signal from a head unit such as a radio. The switching rates are very high, far above human hearing, and the amplified signal is filtered to remove the high frequency part of the signal to maintain the fidelity of the output signal. MOSFET has the property of having good efficiency at low voltages (less than 200 V). In the context of amplifiers, a MOSFET amplifier can drive speakers to kilowatt power levels with good clarity and fidelity, which is especially useful for power hungry speakers such as subwoofers. Because of the efficiency of MOSFETs they produce less heat and require less cooling, which allows reduction in size and cost due to smaller heat sinks to handle the temperature. MOSFET is not confined to amplifiers, and MOSFET circuits are the design of choice in most microchips manufactured today.
Power transferred from an amplifier to a speaker is measured in watts. Power ratings are an indication of the power the amplifier can supply. Amplifier power can be measured in different ways. For example, there is peak power output, which represents the amount of power which can be produced for a very brief period of time. However, for amplifiers the general convention is to measure the RMS (“root mean square” – see below) power. This is the maximum output of the amplifier using a continuous sine wave input signal at the onset of clipping. Clipping is basically the level of power at which you cause an arbitrary amount of total harmonic distortion (THD). RMS power ratings are sometimes referred to as “continuous power ratings.” Since music signals are not sine waves, the RMS power is actually only an approximation of the power, but it is a reasonable way to compare amplifiers. The RMS power rating should be viewed as the maximum power produced by an amplifier within an acceptable range of THD in a particular band of frequencies, typically 20Hz to 20kHz for music amplifiers.
Root mean square (RMS). Okay, now for the mathematically inclined. The root mean square is a statistical measure of the magnitude of a quantity which can vary in value. It is particularly useful when a varying quantity can be either negative or positive, as is the case with sine waves. To calculate the RMS value you square the value of each quantity, or each value in a continuously varying quantity. The squared values are then added and the mean (for practical purposes the arithmetic average) is calculated. The square root of the mean is then the RMS value. In essence it is the square root of the mean of the squares. Aren’t you sorry you asked?
A subwoofer (or sub) is a loudspeaker used for very low-frequency sounds with great power, frequencies known as the “bass.” The typical frequency range for a subwoofer is about 20–200 Hz for consumer products. Subwoofers are intended to augment the low frequency range of loudspeakers (see “midrange speakers” and “tweeters”) which are designed to cover higher frequency bands and which typically do not handle low frequencies well. The combination of speakers provides greater depth to the overall sound of the music. Subwoofers are often quite large, with 10″ to 15″ subwoofers common. For best performance typically subwoofers are placed in a loudspeaker enclosure capable of resisting deformation while withstanding the air pressure caused by the power of the low frequencies.
A tweeter is a speaker that reproduces only higher audio frequencies. The name is derived from the high pitched sounds made by some birds, especially in contrast to the low woofs made by many dogs after which low-frequency drivers are named (woofers). The average tweeter outputs frequencies from approximately 2,000 hertz (Hz) to 20,000 Hz, which is considered to be the upper limit of human hearing. Because a tweeter is limited to high frequencies, it is combined with speakers that reproduce other frequencies to produce a full range of audible sound.
Typically tweeters use a voice coil suspended in a fixed magnetic field. When current from an amplifier is applied to the coil, a varying magnetic field is generated. The coil works against the magnetic field of a fixed magnet which is part of the tweeter. As the coil is forced to move it moves a diaphragm attached to it. The mechanical movement of the diaphragm is determined by the signal supplied by the amplifier. The movement of the diaphragm vibrates the air, which causes audio waves which we hear as high sounds.
The material used in the tweeter effects the type of sound produced. Generally, tweeters made of soft materials, like polypropylene, textile blends, or silk will give a sound that’s refined and somewhat mellow, whereas hard materials, like metal, ceramics, or graphite, produce highs that are bright and snappy.
Dispersion is the extent to which the tweeter yields sound over a given area; that is, the area in which the sound is best heard. Dispersion is a major concern in tweeters because high frequency sound is much more directional than the low frequencies produced by woofers. Piezo (piezoelectric) describes the ability of certain crystal lattices to respond by flexing in proportion to the amplitude and frequency of an incoming signal. Piezo tweeters are very efficient drivers. A diaphragm is the sound-producing element in a tweeter and is the surface that produces the sound. It can be driven by several technologies, including piezo or conventional dynamic diaphragm.
Cone tweeters are noteworthy for being the most economical but having a limited dispersion pattern. They are similar in style to woofer cones but adapted for the production of high frequency sound. They are infrequently used now, having been largely replaced with domes.
Dome tweeters are the most common type. They are more accurate than cone tweeters and have low distortion and a much wider dispersion pattern. Typical dome materials can be soft or hard, and include metals such as neodymium or titanium for extended high frequency response, plastics such as Mylar, or even silk for smoother sound. Combinations of materials are also used. They can be also powered by a magnet and coil diaphragm, or by a piezo driver. All have relatively low mass and high power handling capabilities.
A bullet tweeter is a type of dome tweeter in which there is a large passive, bullet-shaped device above the center that expands the dispersion angle of the sound so that it covers a greater area with a relatively small driver.
Horn tweeters have a relatively small emitter at the apex of a “horn” shape. This is an effective and powerful way of radiating high frequency, but they tend to be very directional and may lack the extended range of the dome tweeters. They are also powered by a magnet and coil diaphragm, or by a piezo driver. Some versions with wider dispersion can be used in car audio applications. High frequency drivers in horns are often referred to as “compression drivers.” This type is more efficient than other types and can be used to reduce the amount of thermal stress on a voice coil.
Onyx Car Amplifiers
Here come the real bad boys. Onyx car amplifiers are the most powerful Class D Monoblock amplifiers in the BOSS lineup, up to 2800W RMS/5500W max. Whether your thing is to get crazy loud or just watch your roof flex, this is it, period. State of the art circuitry and power supply design optimize efficiency and let these MOSFET power amplifiers deliver awesome power with plenty of headroom.
But it’s not all about ultimate power. Whether you’re into hip hop, rock, jazz, fusion, funk, rap, or crunk, any music that slings an authoritative bass line will be better with the deep bass tones from your favorite subwoofers as they push serious air powered by Onyx low noise car amplifiers.
The best car amplifiers let you have more control over your listening environment. Onyx car amplifiers include a full-features set of controls to let you customize your system and get the most from your car amplifier. High level signal from your car speaker wires? No problem – line and speaker level inputs are standard. And with all Onyx power amplifiers you have an amplifier with remote to control your subwoofers.
Of course you need to do more than just power your subwoofers. You may need a two- or four-channel amplifier that is bridgeable. Not to worry. With seven Onyx models to choose from, there is a car amplifier for every system, whether you just need a Monoblock Class D amplifier to push your subwoofer or a 2-channel or 4-channel amplifier to power your whole car audio system.
Armor Car Amplifiers
Why sacrifice performance for convenience when there are Armor car amplifiers? Hip hop, rock, jazz, fusion, funk, rap, crunk, or whatever you find next, your favorite subwoofers will be pushed to the limit by the Armor low noise car amplifiers with power up to 1600W RMS/4000W max. Despite the huge power of these car amplifiers, the power is efficiently delivered without excess heat.
The best car amplifiers let you make choices about your listening environment. Armor car amplifiers include a full-featured set of controls to let you customize your system and get the most from your car amplifier. And the Armor series gives you an amplifier with remote to control your subwoofers.
Available as Class D Monoblock, MOSFET Monoblock, or MOSFET bridgeable 2-channel amplifiers and 4-channel amplifiers, Armor car amplifiers give you the flexibility to choose the best car amplifier for your car audio needs whether you are just pushing your booming subwoofer, or powering your entire suite of car speakers with a multi-channel amplifier.
You need power, but space is limited? No problem – Armor’s design packs incredible performance into a slim package. In fact, the feature-rich performance and put-it-anywhere convenience are so hard to find in the automotive environment that the Armor series may be forging its own product category. And as a bonus you get the styling of the Armor series.
Chaos Epic Car Amplifiers
The Chaos Epic series is the “flagship” of the BOSS line-up. It brings you the best of BOSS’s long-standing devotion to extraordinary sound quality at an affordable price. The Epic series is the value-based answer for anyone who wants to bring their 12-volt entertainment fully into the 21st Century.
The Epic series includes Class D Monoblock, MOSFET Monoblock, and MOSFET bridgeable 2-channel amplifiers and 4-channel amplifiers. In addition, there is a 5-channel bridgeable which allows you to drive the usual complement of car speakers and a subwoofer, each with its own amplifier. And you won’t have a shortage of power with power ratings up to 1600W RMS/4800W max.
With a full-featured set of controls you can get the most from your car amplifier and tweak it to suit your tastes. Remote subwoofer level control is included with all Epic amplifiers except the CE202 and CE404. Why settle for less than the exceptional sound you want for your unique car audio system when you can create a truly immersive listening environment of your own.
Chaos Exxtreme Car Amplifiers
Chaos Exxtreme car amplifiers were designed to deliver clean power needed to bring out the best in your car audio system. And power is delivered, up to 1200W RMS/3500W max. With five 4-channel and seven 2-channel MOSFET power amplifiers, two Monoblock Class D amplifiers, and three Monoblock MOSFET power amplifiers, Chaos Exxtreme takes performance to another level. In addition, there is a 5-channel MOSFET bridgeable power amplifier which allows you to drive the usual complement of car speakers and a subwoofer, each with its own amplifier.
BOSS has not skimped on the full-featured range of controls so your car listening environment is under your control. Remote subwoofer level control is included with all Epic amplifiers except the CX150 and CX350. The Exxtreme series has it all.
Riot Car Amplifiers
The elegant minimalist design of the Riot car amplifiers is deceptive. There is nothing minimal about the power it provides or the authentic nature of the sound it lets you produce. To make this your best car amplifier, BOSS has made sure that the level of features is exceeded only by the level of your enjoyment. The full set of control features includes a remote subwoofer level control. And all Riot amplifiers feature the blue illuminated BOSS logo.
Whether you want a Class D Monoblock, MOSFET Monoblock, or MOSFET bridgeable 2-channel amplifier or 4-channel amplifier, Riot is ready for you. The Riot series of car amplifiers is only the latest reason that BOSS has led to way in 12-volt entertainment for almost a quarter of a century.
Phantom Car Amplifiers
Phantom car amplifiers are second only to the Onyx series when it comes to power. Whether you’re beating the cones of your subs with power up to 1800W RMS/5000W max, or just listening to the authoritative bass line in your favorite music, you’ll have the power and clarity you want from your car audio system.
To have the best car amplifier you must be able to make choices about your listening environment. Phantom car amplifiers include a full feature set to let you customize your system and get the most from your car amplifier. And all Phantom power amplifiers give you an amplifier with remote to control your subwoofers.
Available as Class D Monoblock, MOSFET Monoblock, MOSFET bridgeable 2-channel amplifiers, and MOSFET and Class D (non-bridgeable) 4-channel amplifiers, the lineup of seventeen car amplifiers gives you the flexibility to choose the best car amplifier for your car audio needs. Of course subwoofers are not your whole system. There are eleven 2-channel or 4-channel amplifiers to choose from so there is a car amplifier for every system. Whether you just need a Class D Monoblock amplifier to push serious air with your subwoofer or a 2-channel amplifier or 4-channel amplifier to power your whole car audio system, the Phantom series has the relentless power you need.
Onyx Car Subwoofers
Onyx dual coil subwoofers are designed to be some of the best sounding in the market with crisp, clear, pounding bass. They are built for you with the highest quality parts for tremendous bass response to deliver high-end performance in any installation – at an affordable price. Onyx subwoofers have weather resistant cones and durable rubber surrounds, and are available in a flat style for shallow mounting. Available in 10″ and 12″, the peak power ratings from 1400W to 2500W are the highest in the BOSS line of car subwoofers. If you need more bass system for your car you’ll just have to buy two of them!
Armor Car Subwoofers
In keeping with BOSS’s commitment to providing the latest in car audio, the Armor series of subwoofers is being launched in 2012. Built with the unmatched combination of quality and price that is BOSS’s philosophy, the dual coil 10″, 12″, 15″ subwoofers provide thumping bass with a kick of quality to give you a distinctive car audio system.
Phantom Car Subwoofers
Phantom subwoofers provide extraordinary cosmetics with solid bass performance at an affordable price. The poly injection or electroplate injection cones are weather resistant and durable, and they have a long-lasting butyl rubber surround. Some models are available in a flat style for shallow mounting. The dual voice coil in most models gives you series/parallel flexibility in wiring to satisfy your system requirements. With peak power ratings from 800W to 2500W, there is a Phantom for every need.
Chaos Epic Car Subwoofers
Chaos Epic subwoofers are available in 12″ and 15″, with peak power ratings from **W to **W. Dual voice coils give you series/parallel flexibility in wiring to satisfy your system requirements. They are available with either a non-pressed paper cone** or a custom tooled high efficiency injection cone.
Chaos Exxtreme Car Subwoofers
Go extreme – Chaos Exxtreme. This series provides 10″, 12″ and 15″ subwoofers, with peak power ratings from 1200W to 1800W to give any music an authoritative bass line. Dual coil models provide series/parallel flexibility in wiring to satisfy your system requirements. Affordable single coil models are available in 8″, 10″, 12″, and 15″ with peak power ratings from 400W to 1000W. Chaos Exxtreme subwoofers come with weather resistant and durable poly injection cones, except for the 12″ CX122 which boasts a custom tooled high efficiency injection cone and unique styling – check it out.
Onyx Car Loudspeakers
Onyx 4-way coaxial car speakers are available in 4″, 5.5″, 6.5″, and 6″ x 9″ sizes. They are all built to deliver high-end performance with a great bass response, full-range sound, and smoother highs. Peak power handling is 250W to 800W.
Phantom Car Loudspeakers
Phantom car audio loudspeakers continue the BOSS commitment to bringing you the best car speakers at an affordable price. The Phantom series uses high quality poly injection cones with rubber surrounds for top performance. A custom tooled bridge houses midranges and tweeters for outstanding mid and high frequency response. Custom styling adds to the value of the Phantom series, including the SK series which provides visual excitement when the SKULL eyes light up to the beat of the music.
If you can’t find a Phantom car speaker that fits your system, it system must not be in a car. The Phantom 2-way, 3-way or 4-way speakers include 4″, 5.25″ and 6.5″ round; and 4″ x 6″, 5″ x 7″, and 6″ x 9″speakers from 250W to 800W peak power. If you want to try your hand at placing your speakers for the sound you want, give the 6.5″ SK65 component system with its neodymium tweeter a shot, or the PC65.2C component system with the die cast aluminum frame found in all the P series and PC series Phantom car speakers.
Chaos Car Loudspeakers
The Chaos series of car loudspeakers provides a full range of size and capability. These 2-way, 3-way, 4-way, or 5-way speakers include 3.5″, 4″, 5.25″ and 6.5″ round; and 4″ x 6″, 4″ x 10″, 5″ x 7″, and 6″ x 9″speakers from 140W to 600W peak power. You can also get a 6.5″ 2-way component system if you want to try your hand at placing your speakers. Space a concern? No problem – use the SE651S 6.5″ 2-way speaker with a 1-3/4″ mounting depth.
Chaos Exxtreme Car Loudspeakers
Do you want unique styling in your loudspeakers in addition to high performance? The look you choose makes a statement about your system. Check these out and you’ll know why these car speakers are called Chaos Exxtreme. The red metallic cone is intense, while the rubber surround provides smooth response and durability. Chaos Exxtreme even offers a series within this series featuring a bold design.
These 2-way, 3-way, 4-way, or 5-way speakers include 3.5″, 4″, 5.25″ and 6.5″ round; and 4″ x 6″, 4″ x 10″, 5″ x 7″, 6″ x 9″, and 7″ x 10″ speakers from 140W to 700W peak power. Space a problem? No problem – use the CH6500 6.5″ 2-way speaker with a 1-3/4″ mounting depth. Replacing an existing speaker? No problem – use the 2-way 6.5″ CH6552 duo-fit car speaker which replaces either a 5.25″ or 6.5″ speaker.