Car Audio Glossary

The metal frame that holds all the components of a subwoofer together. The basket’s rigidity and resistance to resonance help determine the sub’s sound quality.
Box volume
This measurement, listed with each component subwoofer, tells you the recommended interior volume in cubic feet that an enclosure should have to get the best performance from the sub. A variation of 10-20 percent is generally acceptable.
Damping factor
The ability of an amplifier to control the movement of a subwoofer the higher the damping factor, the greater the accuracy. Damping factor is calculated by dividing the subwoofer impedance by the output impedance of the amplifier. An amplifier’s damping factor will decrease as the sub’s impedance decreases that’s why an amp running at 4 ohms will provide tighter bass than at 2 ohms. This spec is not always given for all amplifiers.
Decibel (dB)
The standard unit of measure for expressing relative power or amplitude differences. A decibel describes the ratio between the value of a measurement and a reference point. With audio, it often represents loudness, or sound pressure level (SPL). One dB is the smallest change in loudness most people can detect. A 1 dB difference is barely noticeable, but a 10 dB difference is big a speaker playing at 10 dB higher volume will sound roughly twice as loud.
Dual voice coil subwoofer
While typical speaker drivers have one voice coil, dual voice coil (DVC) subwoofers allow you the advantage of flexibility in wiring your system. Parallel wiring provides for maximum amplifier output, while series wiring lets you configure multiple woofers to one amplifier at an acceptable impedance. In series/parallel mode, you can wire 4 woofers to a single amp, for example, and still maintain a compatible impedance. Independent wiring lets you drive a single sub without bridging (or by bridging a four channel amp to one sub).
Enclosure type: Sealed box
A sealed box is an airtight enclosure housing your subwoofer. A sealed box is best for any music that demands tight, accurate bass. Expect flat response, deep bass extension, and excellent power handling. Since a sealed enclosure tends to require more power than a ported box, use an amplifier with ample wattage for optimum performance.
Ported box
A ported box uses a vent (called a port) which allows movement of air in and out of the enclosure chamber. This additional air movement reinforces low bass response. You get more output from a ported box than you would from a sealed box at any given level of amplifier output. Some people simply prefer the sound of ported boxes for rap, techno, or any hard-driving music because they play louder than comparable sealed boxes.
Bandpass box
A bandpass box is a special type of ported box designed for maximum slam. The woofer is mounted inside a dual-chambered box; the woofer fires from the sealed chamber into the ported chamber, and sound waves emerge from the ported side. Because the sound that comes out of the port is extra loud within a narrow frequency range, bandpass boxes are considered super efficient. Their aggressive sound is popular with many hip-hop, techno, and metal fans.
Free-air subwoofers
A free-air system consists of woofers mounted to a board attached to the rear deck or placed in the trunk against the rear seat. The trunk acts as the enclosure housing the subwoofer. Free-air systems save space and have flat frequency response. The woofer must be specifically designed for free-air use, and the trunk must be airtight for best results.
Frequency range
The range of sounds from lowest to highest that the subwoofer is capable of reproducing. The figures listed with the drivers are furnished by the manufacturers. The actual range you’ll hear can vary depending upon the type of box, crossover point, and the vehicle the subwoofer is installed in. Under most circumstances, a typical sub will play slightly deeper than its published figures indicate. So, don’t base your choice solely on this spec.
The resistance offered by an electric circuit to the flow of alternating current measured in ohms. A subwoofer rated at 2-ohm impedance will produce more output than a 4-ohm subwoofer, given similar input wattage, because the resistance is lower.
Peak power
The amount of power the subwoofer can handle as a brief burst during a musical peak. You should not drive your subwoofer continuously with wattage equal to the peak power rating.
In order to get the polarity right, you must wire the positive speaker terminal to the positive amplifier terminal, and the negative speaker terminal to the negative amplifier terminal. Proper wiring ensures that all the cones in a multiple speaker setup will move in the same direction at the same time. If you wire your speakers improperly, one speaker cone will move backward while another is moving forward, canceling out much of the sound both speakers are trying to make.In multiple component subwoofer systems, getting the polarity wrong could short-circuit the amplifier’s output, resulting in overheating and damage to the system.
Pole Piece
A solid piece of steel which protrudes up through the magnet into the voice coil assembly, concentrating the energy from the magnet.
Power range
An external power amp is required to drive any raw component subwoofer. (Don’t try to drive one with your in-dash receiver’s built-in amplifier.) The low number listed is the absolute bare minimum wattage required to get acceptable sound from the subwoofer. For best results, use an amplifier that provides a power level (RMS, or continuous watts) in the upper part of the subwoofer’s recommended range (RMS).
Also referred to as efficiency (measured as SPL sound pressure level), this specification is quoted in decibels (dB). The higher the number, the more efficient the subwoofer is at turning amplifier power into sound, and the louder it plays. A subwoofer rated 3 dB more than another will require only half the power to produce the same output.
The spider (also known as the damper) controls the cone’s movement and keeps the voice coil centered in the air gap. It acts like a shock absorber, smoothing out the cone’s ride.
Part of the sub’s suspension, the surround keeps the cone centered as it moves in and out of the basket. It’s usually made of a durable material like treated foam or rubber in order to withstand the punishing job of producing big bass.
Thiele/Small Parameters
These are terms used to describe the characteristics of a particular subwoofer. They include resonance frequency of the driver, the woofer’s excursion, and air displacement, among others. These figures are useful in predicting subwoofer performance and constructing appropriate enclosures.
Top mount depth
Tells you the depth of the woofer when it is installed from above the mounting surface. The depth will be greater for subwoofers that are mounted from below the mounting surface.
Voice Coil
The voice coil consists of a former (or bobbin) with wire wound around it. The voice coil is attached to the bottom of the cone and extends into the air gap surrounding the pole piece. The voice coil translates the magnet’s energy into cone motion.
4 Ohm Stable
The lowest impedance accepted by the amplifier will be 4 Ohm, which won’t be a problem, as most automotive speakers are 4 ohm impedance.
2 Ohm Stable
Amplifiers capable of powering speakers at lower impedance produce more power. This amp can comfortably power speakers with all channel(s) being used at a 2 ohm load.
1 Ohm Stable
An amplifier that is capable of delivering power at a 1 ohm load is usually reserved for serious subwoofers that can take the power. Please note this particular amp needs a healthy electrical system that is capable of delivering the current the amp demands.
Accessory (position)
Refers to the position of the key in the ignition switch; A wire showing 12 Volts (+) when in this position.
The study of sound. The science of production, effects and transmission of sound waves through various mediums, and the effects of absorption, diffraction, interference, reflection, and refraction.
A device that is turned by a motor to produce AC voltage, which is then rectified (turned into DC) and used to supply voltage to the vehicle’s electrical system.
Alternator Whine
A whining that is heard when the RPM of an engine increaseusually the result of a voltage differential created by more than one ground path or a poor ground path (ground loop).
American Wire Gauge (AWG)
A standard of the dimensional characteristics of wire used to conduct electrical current or signals. AWG is identical to the Brown and Sharpe (B & S) wire gauge.
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).
Amplifier, Class A/B
Class A/B amplifiers have been long known for their ability to produce great quality (Class A portion) while having efficiency better than pure Class A amplifiers. We designed specific circuitry that reduces distortion further and increasing the sound quality and power.
Amplifier Class D
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 amplifiers 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.
Amplifier, Power
An amplifier designed for driving loudspeakers and having a higher power output than a line amplifier or preamplifier.
Amplified Subwoofer
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.
Auto Loud
Automatically provides low frequency boost for listening at low levels.
Auto Memory
A tuner feature that automatically finds the strongest stations in the local area, and places them in preset memories
The relative volume level between two channels, usually the left and right channels. Balance may also refer to the relative volume between front and rear channels of an audio system.
The rigid frame of a speaker that supports all of its components.
The low audio frequency range typically below 500 Hz (hertz).
The use of two amplifiers: one for the amplification of lower (bass) frequencies, and the other for higher (midrange and treble) frequencies. The audio signal from the head unit or pre-amplifier is passed through an electronic crossover and divided into two separated signals. These signals are sent to the respective amplifiers and their outputs are sent to the respective speakers (bass to woofers, midrange and treble to mids and tweeters through the use of passive crossovers). Tri-Amp is the use of three amplifiers in the same manner with the audio signal divided into three separate bands of frequency by the electronic crossover and so on.
Bottom End
Bass response; referring to the sound qualities of the lowest frequency ranges of a speaker or audio system.
An amplifier when can be bridged to gain more power from the channels available. Usually the power is 2x what the normal power would be on each channel. Bridging an amp is a great way to utilize it when need to power a subwoofer when monoblock amp is not used. Please note, when bridging an amp the final speaker impedance must be no less than 4 Ω.
Built-In Amp
The systems that have built-in amps will not require any additional equipment to get it connected to your existing audio system. The amplified system will need a source input and power, and you’re ready to hear your new improved addition of audio.
Built-in LED
Utilizing the latest illumination technology, LED’s highlight the product and also gives a brilliant accent to it as well.
1 (polarized): An electrical circuit element used to store charge temporarily, consisting in general of two metallic plates separated by a dielectric. 2 (non-polarized): A crossover component used to filter out lower frequencies and allow higher frequencies to pass.
Crossover Filter
The on-board crossovers enable you to tailor the audio in your vehicle precisely. All speakers are not created equal, nor do they play equally. Each type of speaker is designed to play a certain band of frequencies. That’s where a crossover does it job, it filters out frequencies to speakers that weren’t designed to play them. There are two types of crossovers, a Passive and Active. Passive crossovers rely on components that do not require an external power circuit, and will connect in between the source unit and speaker. An Active crossover will require power to function. It’s generally more adjustable than passive, and is what is on board on our amplifiers. This equates to a better sounding audio system and longevity to your speakers. The rate at which a crossover functions is measured in “dB per octave” ; generally a steeper slope is better for speakers because they can be “filtered” at a lower frequency.
Audible distortion that occurs when continuous power-to-peak power capabilities (headroom) are exceeded. “Turn it down!”
A speaker composed of larger cone for low range frequencies and a smaller cone or tweeter for higher frequencies aligned on the same axis. A crossover network is necessary to route the proper signals to each driver. These may be passive (usually included). If the speakers are bi-amplified, an active crossover will be used to route the proper range of frequencies to the respective amplifier channels.
The most common shape for the radiating surface of a loudspeakerthe part that moves air.
Constant 12 V (+)
A lead, wire, or connection point that shows positive 12 volts regardless of ignition key position or any other switch; Positive terminal of 12 volt battery.
Crossover Frequencies
The frequencies at which an active or passive crossover network divides audio signals, expressed in Hertz (Hz).
Crossover Network
A unit that divides the audio spectrum into two or more frequency bands, the two types are active and passive.
The rate of flow of electricity, measured in amperes (amps).
Digital to analog convertera component or circuit that is used to derive or convert an analog signal from a digital one.
The reduction of the magnitude of resonance by the use of some type of material.
Damping Factor
The ratio of rated load impedance to the internal impedance of an amplifier -the higher the value, the more efficiently an amplifier can control unwanted movement of the speaker coil. A high damping factor is crucial for large speakers that reproduce bass. Damping factor is calculated by dividing the load (speaker) impedance by the impedance of the amplifier. Thus, a given amplifier’s damping factor will decrease as the speaker’s impedance decreases. This means an amp running at 4 ohms will provide tighter bass than at 2 ohms.
A unit of measurement that indicates the decibel level relative to a reference level.
Decibel (dB)
The basic unit of measurement in electronic and acoustic worka logarithmic scale to express the difference between two values (the ratio of loudness)the threshold of hearing is 0 dB. One dB SPL is the smallest audible difference in sound level. Named for A.G. Bell
Deutsche Industrie Normen (DIN)
German (European) industrial standards. DIN size refers to the stereo size that fits most European automobiles.
Digital Output
An output where the signal is in digital form to allow external processing before being converted to an analog signal
The angle at which a speaker disperses sound. Higher frequencies are narrower than lower frequencies. Tweeters are more directional than woofers.
In a capacitor, it’s the release of stored energy to a load. In a battery, it’s the conversion of chemical energy to electrical energy.
Distribution of sound from a speaker.
Sound that is modified or changed in some waymeasured as a percentage of the whole signal.
Diversity Tuner
An FM tuning method which employs two antennas. The tuner can switch between the two antennas in order to attain better reception.
Digital Multimetergives a precise reading of voltage, current, or resistance (ohms)
A convex speaker shape usually used for tweeters.
Double DIN
Twice the height of the standard DIN dimensions; width is standard DIN width.
Synonymous with loudspeakerThe term also refers to a loudspeaker being coupled to a horn for acoustic coupling and controlled dispersion of sound.
Driver Volume
the amount of enclosure airspace that is displaced by the speaker itself
Dual Mode
An amplifier configuration in which both a stereo speaker pair and mono speaker system (usually a subwoofer) are simultaneously powered by a stereo amplifier
Dust Cap
Part of the speaker that keeps foreign material from falling into the voice coil, which could hinder the speaker’s movement.
Dynamic Range
The difference between the softest and loudest portions of sound that an amplifier or recorder can reproduce within an acceptable range of distortionExpressed in decibels, the higher the number the better.
The ratio of energy output to total energy input, expressed as a percentage. With speakers, this refers to the ratio of total acoustic watts radiated to total electrical watts input.
A box housing a speaker to separate the front sound waves from the rear sound waves.
Enclosure [Sealed]
The subwoofer driver will operate in a sealed enclosure that will yield solid, tight bass. You can purchase a pre-fabricated enclosure or build one to suit your installation needs. It’s a relatively easy enclosure to build and is the smallest enclosure the subwoofer is designed for.
Enclosure [Ported]
A ported enclosure is easy to spot because of the vent or port. It has a benefit over the sealed enclosure, which will output an extra 3-4dB. The enclosure is bigger, but will give you chest thumping bass with authority. An amplifier with a subsonic filter is recommend to properly tune this enclosure, so you get the most out of it.
Enclosure Volume
the total amount of internal airspace of an enclosurethis includes the net, driver and vent volumes.
The process of changing the frequency balance of a signal so acoustical energy is proportional to the electrical input (or any type of relative frequency adjustment).
A component designed to alter the frequency balance of an audio signal.
The control that adjusts the relative volume levels of front and rear speakers in a four speaker system or the front and rear pre-amplifier outputs.
The basic unit of capacitance. A capacitor has a value of one farad when it can store one coulomb of charge with one volt across it.
measured in Hzthe resonant frequency of the air in a port and the stiffness of the air in a ported systemalso known as the tuning frequency of a vented enclosure.
The term used to describe the accuracy of recording, reproduction, or general quality of audio processing.
Fixed DIN Mount
A DIN head unit mounting system whereby no part or component is removable for security purposes
Flat Frequency Response
Term for a circuit or audio system which will pass audio signals that will vary by no more than ± 1 dB usually between 20 Hz and 20 kHz unless otherwise specified.
FM Stereo Separation
The FM tuner demodulator’s ability to separate left and right channel signals of FM stereo broadcastmeasured in decibels, the higher the number the better.
Free Air Response
The frequency at which a speaker will naturally resonate.
The number of wavelengths which pass a specific point in a specific time period, measured in Hertz (Hz)cycles per second.
Frequency Response
The lowest and highest parts of the frequency spectrum that can be reproduced by an audio component within specific limits and tolerances.
Fs or Fo
measured in Hzthe frequency at which a speaker naturally resonates in free air
A device that protects electric circuits by interrupting power in a circuit when an overload occursrated in amperes (amps).
The amount of amplification used in an electrical circuit.
Gauge (wire)
The diameter of a wire. The higher the number, the thinner the wire.
Graphic (equalizer)
Refers to a type of equalizer with sliding controls that create a pattern representing a graph of frequency response changes.
An electrical line with the same electrical potential as the chassis of the vehicle, most commonly negative 12 volts DC.
Ground Loop
The condition created when two or more paths for electricity are created in a ground line, or when one or more paths are created in a shield or an audio cable. This can create undesirable noise such as a high pitched whine when the vehicle is running or pops and clicks when other devices are used in the vehicle.
Ground Potential
In an automobile this is the electrical potential of the vehicles chassis, specifically the chassis of the alternator when the vehicle is running. A circuit, terminal or chassis is said to be at ground potential when it is used as a reference point for other potentials in the system.
Hertz (Hz)
The unit of measurement for frequency. 1 Hz is equal to 1 cycle per second.
High Frequency Driver
A loudspeaker specifically designed to reproduce short, high-frequency wave lengths. The driver typically has a small, lightweight diaphragm. Tweeter.
High Level Input
An input configured to accept speaker level signals.
High Pass Filter
A network of elements used to attenuate all frequencies below a predetermined frequency. Frequencies above the cutoff point pass without any effect.
Term which refers to a set of speaker components used to reproduce frequencies above 500 Hz as in a set of separates. Highs may also refer to tweeters which are used to reproduce frequencies usually above 2.5 kHz. Not bass.
High and Low Level Inputs
Having both of these types of inputs allows owners to add an amplifier to virtually any factory, premium factory, or aftermarket source unit. High level also known as speaker level inputs simply accepts the outputs from a source unit as a signal. Low level also known as “RCA” accepts a pre-amp output signal from the pre-amp outputs of head units.
The reproduction of sound accurately so that the listener can imagine the original environment and placement of the original sound sources accurately within within that environment. The better the imaging the more analogous the reproduced sound will be to the original.
The opposition to the flow of alternating current (AC) in an electrical circuit.
Measured in ohms ()the combined effect of resistance, capacitance and inductance.
Infinite Baffle
A loudspeaker baffle of infinite space that has no openings for the passage of sound from the front to the back of the speaker. Also a sealed enclosure where the internal volume is greater than the Vas of the driver
Input Sensitivity Control
Adjusts the amount of input signal being fed to the amplifier stage to reduce distortion.
Intermodulation Distortion (in loudspeakers)
Is the distortion generated in single cone speakers when the cone is reproducing a high and low frequency simultaneously. The high frequency peaks will be flattened off if the low frequency is distorted in any way.
IPX Rating
IPX is a standard of which tells you how resistant a certain product is against the elements. It can vary from a light spray or dust to complete submersion in water. Products that have been tested and rated have been designed for the user in mind.
ISO-DIN Mounting
Refers to a mounting system in which the head unit is mounted behind the dash panel with side brackets, employing factory installed trim panels (flush mounting).
Kilohertz (kHz)
1 kHz = one thousand hertz or 1,000 times per second. Formerly kilocycles (kc)
Kirchoff’s Current Law (KCL)
A law stating that the total current entering a point or junction in a circuit must equal the sum of the current leaving that point or junction.
Kirchoff’s Voltage Law (KVL)
(KVL) A law stating that the voltage supplied to a DC circuit must equal the sum of the voltage drops within the circuit.
Liquid Crystal Display (LCD)
A type of digital display made of a material that changes reflectance or transmittance when an electrical field is applied to it.
The electrical demand of a process, expressed in current (amps), power (watts), or resistance (ohms).
Loudness Control
Intended to boost low frequencies at lower volume levels and should not be used at high volume listening levels.
An electro acoustic transducer which converts electrical audio signals at its input to audible waves at its outputmay also refer to a given driver of a multiple speaker system and not to the whole speaker system as might a speaker.
Low Frequency Driver
A loudspeaker specifically designed to reproduce long, low-frequency wave lengths. The driver typically has a large cone, magnet structure, and voice coil. Woofer.
Low Pass Filter
A network of elements used to attenuate all frequencies above a predetermined frequency. Frequencies below the cutoff point pass without any effect.
Term which refers to a set of speaker components used to reproduce frequencies below 500 Hz as in a set of woofersmay also refer to the low frequency drivers of a set of separates. Not treble.
Low Profile
The low profile of the driver can fit it many depth constrained spaces that are in many modern vehicles. We have designed the drivers motor, suspension, and cone to allow for audio performance that isn’t compromised because of the lack of basket depth.
Magnetic Structure
The part of loudspeaker comprising the magnet, pole piece, back plate and top plate
Midrange Driver
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.
A common term used to describe a VOM (voltage ohm meter). A multi-meter usually has the ability to measure volts, resistance (ohms), and amperes or milli-amperes.
Net Volume
the amount of airspace within an enclosure (not including the airspace taken up by bracing, vents, or the speaker itself)
Nominal Impedance
The minimum impedance a loudspeaker presents to an amplifier, directly related to the power the speaker can extract from the amplifier.
he interval of eight diatonic degrees between two musical tones.
The doubling or halving of frequencies.40Hz is an octave higher than 20Hz.
The unit of electric resistance and impedanceone ohm is the resistance value through which one volt will maintain a current of one ampere.
Ohm’s Law
Current in a circuit is directly proportional to the voltage, and inversely proportional to resistance. It also includes the relationships of watts to amps, volts and ohms.
OversamplingDoubling or quadrupling (or by even a higher factor of 2 squared) the sampling frequency during the digital to analog process to obtain a high frequency for digital filtering
Parallel Circuit
A circuit configuration in which the same voltage is applied to all components, with current divided among the components according to their respective resistances or impedances. Example: All positive leads of two or more speakers connected together and all negative leads connected together.
A type of equalizer with adjustable parameters such as center frequency and bandwidth (Q) as well as amplitude.
The relative position of two sound waves with respect to each other.
Phase Control
This control feature allows the user to adjust the phase so all audio signals are playing together, the way it’s intended rather than against each other. Bass notes when absent, are very obvious and a quick adjustment to the Phase will remedy that.
Phase Shift
Frequency interaction in the crossover region of passive crossovers which can cause some frequencies to be delayed with respect to other frequencies.
Piezo Electric Tweeter
A very efficient, highly directional tweeter which operates without a crossover or magnetdriver creates sound when a quartz crystal receives electrical energy.
Plug & Play
Plug and play systems are the fastest way to get your music heard. Usually the install is completed by simply plugging in the power. The audio source will be your mobile phone or device and you’re ready to hear music.
Power Handling Capability
measured in RMSThe maximum amount of power that can be safely accommodated without damage in a speaker system. This will vary depending on frequency and length of time the signal is applied.
Pre-Amp Output
This feature allows you to connect and expand your audio system with external devices (i.e. Amplifiers, Processors) through RCA connections. A unit is capable of having up to three pre-amp outputs, front, rear, and subwoofer. Some units might have one or two outputs, but you can still use those outputs for complete system building.
Pre-amp Fader
A circuit that allows effective level control of two amplifiers, built in and external without loss of power.
Protection is key when the things get a little too hot or a speaker fails. In the event when an amp gets too hot, the thermal protection circuit turns on and allows the amp to cool down before turning back on. If a speaker fails, the protection circuit will automatically cutoff power to the output and remain in that state until the short if removed. These safety features allow you to have peace of mind and know the amplifier is monitoring conditions constantly.
The ratio of reactance to resistance in a series circuit, or the ratio of resistance to reactance in a parallel circuit.
The Q of a driver at its free air resonance considering only its electrical losses.
The Q of a driver at its free air resonance considering only its mechanical losses.
The measurement of a speaker and enclosure working together as one, or the total Q of a woofer and sealed enclosure at the system’s resonant frequency considering all resistive losses.
The measurement of the speaker as a motor taking into consideration all mechanical and electrical lossesthe total Q of a woofer at Fs, considering all driver resistances.
Rear Camera Input
When the vehicle is put into reverse, the camera (camera sold separately) will trigger and allow you to have an view of what’s directly behind your vehicle. Certain models will allow for direct viewing while towing a trailer. A safety feature that will improve rear view visibility
Remote Turn On Lead
The lead from the head unit which supplies a signal (12V+) to the “remote turn on” lead of the amplifier turning the amplifier on when the head unit is turned on, and allowing the amplifier to be mounted in a location out of reach of the user. This is NOT the amplifier’s main source of power.
PitchWhen you tighten a drum, you raise its resonance.
Resonant Frequency
Frequency at which there is a response peak, due to a specific interaction of inductive and capacitive circuitry in an audio devise or system.
RF Modulator
A device that converts a signal (typically audio and/or video) into a radio frequency
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.
A description of the shape of the pass band. S values range from .4 to 1. An s value of .7 is considered ideal due to its flat frequency response.
S Factor
the bandpass enclosure’s frequency response in the pass bandit is a general indicator of bandwidth.
Sealed Enclosure
A type of speaker enclosure that does not allow the pressure generated by the back wave of the speaker to leave the enclosure.
Sealed Volume
The amount of enclosure airspace on one side of a woofer in a bandpass system, that acts as a sealed enclosure.
Sensitivity (loudspeaker sensitivity)
The sound pressure level a speaker produces when fed by a given input power, measured at a specific distance on axis directly in front of the speaker (Typically specified in dB SPL at 1 meter with 1 watt of input signal).
A speaker system with more than one type of driver. The most common type of separates system is a set containing two high frequency drivers (tweeters), two lower frequency drivers (mids or woofers), and two crossover networks (filters).
The degree to which left and right channels in a stereo signal can be kept apart.
Series Circuit
A circuit configuration in which a single current path is arranged among all components: connecting the positive speaker output of an amplifier channel to the positive terminal of speaker # 1, the negative terminal of # 1 to the positive terminal of speaker # 2, and the negative terminal of # 2 to the negative output of the same amplifier channel is a series connection.
Signal to Noise Ratio S/N
The ratio of the desired signal level to the level of unwanted noise (measured in decibels).

Signal-to-Noise Ratio - Times Signal is Greater than Noise
10.0 dB 	3.16
20.0 dB 	10.00
30.0 dB 	31.62
40.0 dB 	100.00
50.0 dB 	316.20
60.0 dB 	1,000.00
70.0 dB 	3,162.00
80.0 dB 	10,000.00
The rate of boost or attenuation expressed in decibels of change per octave.
Sound Pressure Level (SPL)
An acoustic measurement of sound energy, typically expressed in dB SPL. Theoretically, 0 dB SPL is the threshold of human hearing at 1 kHz, while 120 dB is the threshold of pain.
Sound Stage
The area that appears to be occupied by sonic images. as with a real stage, a sound stage should have depth, height, and width.
A transducer which converts electrical energy into acoustical energy (sound).
measured in dBthe speaker’s reference efficiency measured with 1 watt input at a distance of 1 meter from the center of the cone.
Strapping Capability
Two amplifiers can be “linked” together to make double the power at high impedance (2 Ω) The benefits are less electrical current needed than 2 individual amps at 1 Ω, and only a single set of signal RCA cables.
Selectable LP Slope
Having this feature on subwoofer amp is priceless. It allows you to choose a 12dB or 24dB slope, allowing you to further tune your subwoofer system precisely. A slope simply dictates how sharp the rate at which the crossover cuts off.
Steering Wheel Controls (SWC)
Boss Audio head units have the ability to interface to your vehicles SWC, allowing you to control functions of the radio right from the steering wheel. An interface module might be needed however based on your vehicle make/model.
Stereophonic (stereo)
Consisting of two or more audio channels in an audio system during recording and playback to give a more natural distribution of sound.
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 high frequency driver designed to reproduce very high frequencies, typically over 10 kHz.
Subsonic Filter
A subsonic filter is fancy word for “High-Pass” filter. That being said, it’s a high-pass for the subwoofer. This is especially true when you have the sub loaded in a ported enclosure, where the port will start to make noise. The subsonic filter tuned around the lowest frequency the subwoofer or port will play making a bit more efficient rather it trying to reproduce frequencies that it can’t.
Subwoofer Level Control
An added feature on our amps, allows you control level of the subwoofer from an included mountable wired remote. The RJ45 style plug connects to the amplifier and remote.
Switchable Input Sensitivity
In order to properly adjust the input sensitivity of an amp, the output level must be within the range of the input of the amplifier. Our selectable input gives you the freedom to connect the amp to any source unit and have peace of mind it will be within range to properly use the volume settings on your source unit the way it was designed.
Switchable Tuner
Different countries around the world have requirements for broadcasting radio frequencies. Our radios have a selectable tuner area that allows you to receive radio broadcasts no matter where you are in the world. (US, EU, Asia, ORIT, Americas)
Threshold of Pain (in dB SPL)
The minimum value of sound pressure of a given frequency that will cause pain to a listener 50% of the time: Discomfort begins at 118 dB SPL. Actual pain starts around 140 dB SPL within the frequency range between 200 Hz and 10,000 Hz.
Total Harmonic Distortion (THD)
The noise referenced to signal in decibels (dB) as a percentage.

Noise referenced to Signal - Percent of Distortion
-10.0 dB 	31.6%
-20.0 dB 	10.0%
-30.0 dB 	3.16%
-40.0 dB 	1.00%
-50.0 dB 	0.316%
-60.0 dB 	0.100%
-70.0 dB 	0.0316%
-80.0 dB 	0.0100%
A component (or section of one) that receives radio signals and selects one broadcast from many.
The tendency of an enclosure to produce no spring or pressure on the woofer. Unloading produces an uncontrollable over-excursion of the woofer cone (it vibrates out of control); the speaker will exhibit low power handling at lower frequencies.
Volume Acoustic Suspensiona measurement in liters or cubic feet of the volume of air that is equal to the compliance of the speaker’s total suspension.
measured in inches3, feet3, or liters3the internal volume of air of a given enclosure.
the volume of air displaced by the speaker’s cone during an Xmax displacement.
Vent Dimensions
vent diameter X (by) vent length.
Vent Volume
the amount of enclosure airspace that is displaced by the vent
Vented Volume
the amount of enclosure airspace on one side of a woofer in a bandpass system that acts as a vented enclosure
Video Output
If you have additional video monitors, the video output can be connected to the additional monitors, giving you an expanded video throughout your vehicle.
measured in inches3, feet3, or meters3length x width x height
Volt-Ohm-Metermultimeter that measures voltage, resistance (ohms), amperes, and milliamperes
Voice Coil [single]
A subwoofer with a single voice coil has an impedance of 4 Ω. It can be powered by an appropriately matched amplifier, or be combined with several other single voice coil subwoofers wired in a series or parallel configuration. Usually a single voice sub is perfect for low to medium powered applications
Voice Coils [dual]
A subwoofer with dual voice coils offers a couple of advantages over a single coil. You will have more wiring configurations. If you add additional subwoofers, wiring configurations can be matched to amplifiers easily to access the power needed. Power handling goes up as well since there an additional coil to power. Dual voice coils subwoofer will work in medium to high power applications.
Voice Coil [3ohm]
Our 3 Ohm voice coil is compatible with all automotive head units. We use a specially designed coil to for extra sensitivity to the speaker, leading to increased output.
Watt (wattage)
A measurement of real powerThe product of voltage and current in a resistive circuit
A loudspeaker made to reproduce the lower range of the audio spectrum (bass), in a 2-way or more complex speaker system.
measured in inches or millimetersthe maximum linear cone excursion of a driver.
A speaker system with two types of drivers (see also COAXIAL)
A speaker system made up of three different types of drivers.
Advanced Audio Distribution Profile (A2DP) This profile defines how high quality audio, stereo or mono can be streamed from one device to another over a Bluetooth connection.
Android Auto
Android Auto is a smartphone projection standard developed by Google to allow mobile devices running the Android operating system (version 5.0 “Lollipop” and later) to be operated in automobiles through the dashboard’s head unit. The standard offers drivers control over GPS mapping/navigation, music playback, SMS, telephony, and web search its key feature is hands-free operation through voice commands and is compatible with apps including Google Maps, Google Play Music, MLB at Bat, Spotify, Songza, Stitcher, iHeart Radio, and TuneIn.
To turn down or reduce.
Attenuator with Smooth Volume Return
Designed to reduce signal overload to correct distortion while returning audio to the correct volume
Usually accompanies track search and allows the user to skip from the end of one track to the beginning of the next missing out any blank or unrecorded passages on the tape.
Auto EQ
Automatic equalization sets the bass, middle and treble at the optimum level to improve your listening experience
Head unit’s volume automatically increases along with car’s speed eg. JVC’s Cruise Control.
Benefits the long distance driver by scanning the waveband in the area of travel and automatically storing five or six strongest stations in order of signal strength.
Aux in
Auxiliary Input. A basic connection between an mp3 player & a car stereo. The connection is made via a cable with a 3.5mm headphone jack at each end.
The angle of contact between head and tape during recording and playback. Should be as similar as possible for the most faithful reproduction and the best quality.
Back-up Memory
Memory backup stores your pre-set stations and settings when the radio is turned off
A combination of high and low pass filters connected in series with an overlap between the lower and upper freqencies, usually used for the mid-range in a 3-way component system.
The lower end of the frequency spectrum, sometimes also known as mid-bass.
Bass Boost
The Bass Boost button. It’s supposed to be used when you’re listening to music at lower volume levels. Remember from above that at low volume levels we don’t hear the low end and high end as well. When you engage the Bass Boost button on a system it gives a little EQ boost to the low and high end of the material it’s processing.
Bluetooth is a wireless technology standard for exchanging data over short distances. This data can be text, photographic or audio. Bluetooth is used mainly in car audio for making and receiving telephone calls.
Bluetooth Ready
This unit will be Bluetooth enabled with an optional adapter
Where the two separate outputs of some stereo amplifiers can be conbined to give a mono signal.
Car Play
CarPlay is a smarter, safer way to use your iPhone in the car. CarPlay takes the things you want to do with your iPhone while driving and puts them on your car’s built-in display. You can get directions, make calls, send and receive messages, and listen to music, all in a way that allows you to stay focused on the road. Just connect your iPhone via USB and go.
Speakers which have two separate drive units (normally a small woofer and tweeter) moving independently. Essentially this gives better high frequency response and hence greater range and clarity.
Separate speakers, usually a tweeter and mid-range with appropriate crossover.
A selective filter which splits signals into different frequency bands that can be fed independently to separate speakers. A passive crossover filters signals after they have been amplified. An active crossover (more effective and flexible) filters signals before amplification, sending different signals to different amps.
The level of stereo separation ie. the isolation of the two channels of a system.
Clock Time. See RDS
DAB is a digital radio technology for broadcasting radio stations. DAB is more robust with regard to noise and multipath fading for mobile listening.
Digital-to-Analogue Convertor
Digital Audio Tape. Medium used in the pro sector for reproducing pre-recorded material in digital format on tape – not to be confused with DCC.
Philips Digital Compact Cassette, a medium of digital cassette designed to replace the familiar analogue cassette.
Detachable Faceplate
Enables you to remove the car stereo faceplate to deter thieves
DIN E is the German standard of measurement for most in-dash players to enable sets to be fitted in standard slots.
Disabled System Indicator (DSI)
A red indicator blinks on the unit after the faceplate is removed, warning potential thieves
A video codec which became popular due to its ability to compress lengthy video segments into small sizes while maintaining relatively high visual quality.
Dynamic Noise Reduction. Similar to Dolby but not as effective.
Digital Sound (Signal) Processor. Lets you programme a listening environment pattern and change the sound to suit the music. A type of super equaliser.
Speakers which have two cones; the second cone is usually much smaller and glued directly to the centre of the main cone although it has just one voice coil.
Dual zone
Different audio areas of your vehicle, i.e. rear seats rather than front seats
Dual Zone Entertainment
Enables you to set audio to be heard in a particular area of your vehicle, i.e. rear seats rather than front seats
New technology to guarantee perfect FM reception due to much higher selectivity plus improved sensitivity.
Enhanced Other Networks. Allows interruption of RDS bulletins from other local stations.
Equalisation. Each EQ band influences different qualities of a mix or instrument:

50-60 Hz 	adds thump in a kick drum and boom in a bassline
100-200 Hz      adds punch in a snare and richness
200-500 Hz      adds warmth and weight in guitars, piano and vocals
500-1000 Hz     adds body and tone to many instruments
2 kHz 		adds clarity, edge and bite to guitars and vocals
5-10 kHz 	adds clarity, openness and life, especially drums
16 kHz 		adds air, space or sparkle
Control which balances sound from front to rear in a four speaker set-up
enjoy FLAC lossless digital audio files in your vehicle with playback output at CD quality, without the need to convert
FLAC Support
Free Lossless Audio Codec compresses audio without any loss in quality
Term relating to subwoofers which are designed to work most efficiently in free air using the boot for example, as an enclosure. Also known as ‘infinite baffle’
Frequency Response
A car audio system’s frequency response represents how much of the audible frequency spectrum it can reproduce. The frequency response of a car audio system can be measured by an instrument known as a real-time analyzer (RTA), which consists of a microphone attached to a processor with a display that has a graph that shows a system’s response.
Feature of autoreverse decks where fast forward is always forwards, rewind is always rewind, regardless of tape play direction.
Speakers designed to give a wide frequency response.
Degree of signal amplification, achieved by an amp, tuner or pre-amp circuit. Expressed in decibels (dB)
Generic Access Profile (GAP)
Controls connections in Bluetooth and enables your device to be visible to the world
High-Definition Multimedia Interface supports image or video play back on HD TV or PC
Unit of measurement for frequency, oftem written as Hz or kHz
High Level Input
An input configured to accept speaker level signals
(Capacitor) Essentially allows more signal to pass through the higher the signal gets, typically used and supplied with tweeters.
Human Interface Device Profile (HID)
Enables the connection of devices used by Bluetooth HID such as keyboards, pointing devices, gaming devices and remote monitoring devices.
Impedance is a measure of something that opposes/restricts the flow of current in an electrical circuit. In this case, that something is a speaker.
Inrix Services
Connects you to the Inrix network, the worlds leading provider of traffic information
Installer Memory
This function stores the optimum acoustic field set by an expert installer to suit your vehicle
Plays approximately the first 10 seconds of every track on a tape/CD
ISO connector
Allows audio devices to be quickly connected without need for wiring
Pinch roller release when cassette is not in use to prevent tape damage
Two levels of sensitivity for tuner searching, local and distant.
Boosts low frequencies. Useful at low volumes but most loudness circuits can cut off an unacceptable amount of treble.
(Inductor or Choke) Allows more signal to pass through the lower the signal gets – ideal for a sub.
Made for ipod
Play your iPod/iPhone on this unit via the front/rear USB port
Panasonic’s Multi Stage Noise Shaping – Latest Digital/Analogue technology.
Medium Density Fibreboard. Used for building bass enclosures, door panels etc.
Mobile High-Definition Link allowing mobile phones, tablets and other devices to be connected
As the name suggests, frequencies in the middle of the frequency range.
Amplifier power supply switching device designed for optimum performance.
(Denon, Philips, Radiomobile) Music search system. See TRACK SEARCH
Annoying ‘chopping’ interference on FM caused by reception of a signal that’s been reflected (ie. off tall buildings)
A measurement used of how much the flow of electricity is restricted or impeded. The higher the measurement the higher the resistance.
Method used in a CD player to reproduce digital information as faithfully as possible in analogue form, a part of the digital to analogue conversion process.
Programme Identification.
Phase Locked Loop keeps FM signals locked on station.
If the port length and diameter is correctly matched to the box volume and subwoofer’s characteristics it will greatly increase efficiency and a good ported box offers lower distortion.
Controls volume relation between front and rear speakers connected to built-in amplifier.
System loads and ejects CD or tape automatically.
Holds controls for volume, bass and treble but has no on-board amplification.
Adjusts front/rear balance at pre-amp level, used in combination with pre-outs and external amplifiers.
A pre-amp output (pre-out) on a head unit allows the addition of an amp or other peripherals when system building.
Stations which can be held in a tuners memory for instant recall.
Cassette function which allows user to switch from one side to the other.
Programme Service
Programme Type
Quick Release Bracket, denotes extractable unit.
R-CAM Caution on screen display
Displays on screen warning of a hazard when you are reversing your car
R-CAM interrupt
When you reverse your car the reverse camera automatically switches to the camera
Radio reception when tape is set for fast forward or rewind
An RCA connector, sometimes called a phono connector is a type of electrical connector commonly used to carry audio and video signals. The name “RCA” derives from the Radio Corporation of America, which introduced the design by the early 1940s for internal connection of the pickup to the chassis in home radio-phonograph consoles.
RADIO DATA SYSTEM. Traffic information system on FM. RDS shows station name display (PI/PS) and delivers traffic bulletins (TP/TA) Also locks onto best possible frequency for a station in a particular part of the country (AF) Can display time and date on the receiver (CT) Sets with PTY (Programme Type) will automatically tune into a station broadcasting Pop, Classical, News etc.
Root Mean Square. “RMS power” is sometimes used in the audio industry as a synonym for “mean power” or “average power”.
Root Mean Square, a realistic measurement of the maximum output of an amplifier. The higher the figure the more powerful the unit.
The point at which the frequency level/performance of a speaker decreases.
Real Time Analyser. Piece of equipment which measures frequency response and SPL level.
SD Card
Secure Digital or (SD) is a memory card format for use in portable devices, such as mobile phones, digital cameras, sat nav units, tablet computers & more recently car stereo units.
German traffic information system.
Security Code Function (user set)
Set your own number-based security code, deters thieves by disabling unit when input incorrectly
The sound pressure level a speaker produces when fed by a given input power, measured at a specific distance on axis directly in front of the speaker. Typically specified in dB SPL at 1 meter with 1 watt of input signal
Serial Port Profile (SPP)
Enables you to connect more than one Bluetooth device to your car audio system
Indicates how much irritating background hiss is produced as a proportion of the full output power. Numbers higher than 90dB are acceptable. A good indicator of the quality of the amp.
Simple Secure Pairing (SSP)
Enables you to connect any one Bluetooth device to your car audio system
Siri Eyes Free
make use of your iPhone’s Siri functionality through your unit’s external microphone and the speakers of your vehicle
Smooth GUI
Smooth Graphical User Interface visually smooth graphics that respond quickly to inputs
Sound Pressure Level. Monitored using pro kit and measured in decibels – basically the amount of volume produced.
Spotify Link App
Recognises music streaming service Spotify, enabling you to play your Spotify playlists
Where the listening perceives the origin of the music to be coming from.
Stalk Control
Maintain the controls of your steering wheel with an optional adapter.
The ‘thumping rumble’ in a system.
Large speakers designed to produce the low frequencies, designed to be used in a cabinet, tube or free-air application.
Total Harmonic Distortion
Traffic Message Channel (TMC) is a technology for delivering traffic and travel information to drivers. It is typically digitally coded using the FM-RDS system on conventional FM radio. It can also be transmitted on DAB
Traffic Programme/Traffic Announcement. See RDS
Tape facility which means you can rewind or forward to the next track and in some cases to any selected track.
Reproduce the higher frequencies (treble), they are generally fairly small.
Sony bi-directional 8-pin BUS connector for centralised multi-media control from a master unit.
Universal Serial Bus (USB) is an industry standard developed in the mid-1990s that defines the cables, connectors and communications protocols used in a bus for connection, communication and power supply between computers and electronic devices & more recently car audio products. You can play back your saved music or video content in many formats such as mp3, wma, aac, divx, avi.
Windows Media Audio (WMA) is an audio data compression technology developed by Microsoft.
Works with iPhones
This unit will work with your iPhone with either an optional cable or the white USB cable which came bundled with your iPhone.
Caused by any variation in the speed of the tape transport. The lower the figure the better and hence the lower the level of variation through the speakers.