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Glossary

Term Definition
ABX Comparator A device that randomly selects between two components being tested. The listener doesn't know which device is being auditioned.
Accessory (position) Refers to the position of the key in the ignition switch; A wire showing 12 Volts (+) when in this position.
Acoustic Absorption The sound deadening properties of any substance, measured in sabine units. One sabine is equal to the absorption of 1 square foot of surface which will absorb all incident energy.
Acoustic Feedback A squealing sound when the output of an audio circuit is fed back in phase into the circuit's input.
Acoustic Suspension A sealed or closed box speaker enclosure.
Acoustical Energy Energy consisting of fluctuation waves of pressure called sound waves.
Acoustics 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.
Active Arming A method for arming a security system that requires some action such as pressing a button on a remote transmitter or entering a code on a keypad
Active Display A stepup display feature that generates animated patterns for both segment and dot matrix LCDs that proceed the sequential display of information such as clock, Custom File titles and radio station frequencies.
Air Gap The space between the top plate and the pole piece. This is where the voice coil sits.
Aliasing Noise The result of the sampling frequency not being at least double the highest analog frequency during the digital encoding of an analog signal.
Alignment A class of enclosure parameters that provides optimum performance for a woofer with a given value of Q.
Alternate Channel SelectivityA measurement of a tuner's ability to select one radio station's signal and reject the signal of another radio station two channels (0.4 Mhz) away. Measured in decibels, the higher the number the better.
Alternating Current (AC) An electric current that reverses direction at regular intervals. Measured in Volts AC at Hertz, example: 110 volts AC 60 Hz.
Alternator Whine A whining that is heard when the RPMs of an engine increase. The noise is usually the result of a voltage differential created by more than one ground path or a poor ground path (ground loop).
Alternator 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.
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.
Ammeter An instrument that measures the magnitude of an electric current in amperes.
Ampere (amp) A unit that defines the rate of flow of electricity (current) in a circuit.
Amplification The increase in signal level, amplitude or magnitude.
Amplifier Classes Audio power amplifiers are classified primarily by the design of the output stage. Classification is based on the amount of time the output devices operate during each cycle of signal swing. Also defined in terms of output bias current, (the amount of cur
Amplifier 1 A device which increases the level of a signal by increasing the current or voltage. 2 May also be used to isolate or control a signal and even decrease the level as in a line output converter. Class A operation is where both devices conduct continuousl
Amplifier, Power An amplifier designed for driving loudspeakers and having a higher power output than a line amplifier or preamplifier.
Amplitude Modulation (AM) The encoding of a carrier wave by variation of it's amplitude in accordance with an input signal. AM Stereo
Amplitude The maximum value of a periodically varying quantity.
Analog to Digital Convertor (ADC) A circuit that converts an analog signal into a digital signal. With a continuous input signal the ADC will check the signal several time per second (sampling), assign values to the samples and represent it as a binary number (quantization and encoding).
Analog A way to represent data by means of continuously variable quantities. A control or circuit which continuously changes the level of a signal in direct relationship to the control setting. An electrical signal whose frequency and level vary continuously in
Analogous Alike in certain ways. Similar in function but not in origin or structure.
Anode The electrically positive pole of an electronic device such as a semiconductor. A diode, for instance, has a positive and a negative pole; these are known as the anode and the cathode
Antenna Trimmer An adjustment found on analog radios used to maximize AM reception. Turning this trimmer to the point where the sound is the loudest increases the sets signal to noise ratio optimizing performance.
Antenna An apparatus used for sending and receiving radio waves, usually constructed of metal.
Aperiodic Refers to a type of bass-cabinet loading. An aperiodic enclosure type usually features a very restrictive, (damped), port. The purpose of this restrictive port is not to extend bass response, but lower the Q of the system and reduce the impedance peak at
Attenuator A device to decrease or increase the strength of a signal.
Auto Eject Feature of a cassette player that ejects the tape when it has finished playing one side.
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.
Auto Replay Feature of a cassette player that automatically rewinds a tape when it has reached the end of one side, then begins to replay.
Auto Reverse Feature of a cassette player that automatically plays the reverse side of a tape when one side has reached the end.
Auto Stop Feature of a cassette player that automatically shuts off power when a tape has reached the end of either side in any mode.
Automatic Gain Control (AGC) A circuit that continuously adjust the recording amplifier gain to maintain a relatively constant recording level.
Azimuth The perpendicular alignment of the tape to the head of a tape player / recorder.
B Magnetic flux density in gap, in Tesla-meters ™
Back-up Battery A separate battery added to the security system as an alternate power supply to serve as a backup in case the vehicle's main battery should be disabled by a thief.
Baffle A surface used to mount a loudspeaker that separates the front wave of the loudspeaker from the rear wave of the loudspeaker.
Balance The relative volume level between two channels, usually the left and right channels. May also refer to the relative volume between front and rear channels of an audio system. To make the same or equal.
Balanced Referring to wiring: Audio signals require two wires. In an unbalanced line the shield is one of those wires. In a balanced line, there are two wires plus the shield. For the system to be balanced requires balanced electronics and usually employs XLR conn
Balls The strength or power to perform it's task extremely well without loss of performance even when pushed to it's limits.
Bandpass A twopart filter that cuts both high and low frequencies allowing the band of frequencies between these two points to pass.
Bandwidth The range of frequency response between lower and upper frequencies points which audio signals pass through an electrical device or conductor where the signal has rolled off by three decibels.
Barium Ferrite A speaker magnet material made from an alloy with iron and barium for improved magnetic strength
Basket The rigid frame of a speaker that supports all of it's components.
Bass Blockers Commercial name for auto-sound first order high pass crossovers (non-polarized capacitors), generally used on smaller speakers to attenuate low mid/low frequencies.
Bass Reflex A vented enclosure that allows control of rear radiated sound waves.
Bass The low audio frequency range typically below 500 Hz (hertz).
Battery An electrically connected group of cells, wired in series, that stores an electrical charge and supplies a direct current (DC).
BBE Processing A signal processing circuit that provides improvements in imaging and spatial realism by altering the frequency and phase characteristics of portions of the input signal.
Bessel Crossover A type of crossover design characterized by having a linear or maximally flat phase response. Linear phase response results in constant time-delay (all frequencies within the passband are delayed the same amount). Consequently the value of linear phase is
Bi-Amplification 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
Bias A necessary high frequency current applied to the record head along with the audio signal to prevent distortion and increase sensitivity during recording.
Binary Digit (BIT) The smallest unit of data in a digital signal represented by either a one or zero.
BL "The magnetic strength of the motor structure. ""Expressed in Tesla meters, this is a measurement of the motor strength of a speaker. Think of this as how good a weightlifter the transducer is. A measured mass is applied to the cone forcing it back while th"
BNC A type of connection often used in instrumentation and sometimes in digital audio.
Boom, Boomy Excessive bass response or peak in bass response of a recording, playback, or sound system. Dominant in the low frequency range. Without complimentary levels of frequencies other than bass.
Boost To Increase.
Bottom End Bass response; referring to the sound qualities of the lowest frequency ranges of a speaker or audio system.
Bridging Combining two outputs of an amplifier to use as one, usually to a woofer. The provides an increase in power output (wattage) necessary to reproduce lower frequencies at higher volume levels.
Brown and Sharp Gauge(B & S Gauge) A standard of the dimensional characteristics of wire used to conduct electrical current or signals. B & S Gauge is identical to the American Wire Gauge (AWG).
BTL Bridged, Transformer Less. A circuit design wherein two small Integrated Circuit (IC) amplifier channels are bridged together to provide a single, larger output circuit. These circuits are limited by their current capabilities and the amount of heat they
BTM Best Tuning Memory. A feature in which the tuner selects radio stations by signal strength, and assigns them to presets in numerical order, according to their frequency value.
Buffer Commonly found in Mini Disc (MD) and Compact Disc (CD) players, this device protects against vibrations by storing the audio data for uninterrupted playback. Data is available from the buffer when it can not be read from the disc so long as the interrupti
Butterworth Crossover A type of crossover circuit design having a maximally flat magnitude response (no amplitude ripple in the passband). This circuit is based upon Butterworth functions, also know as Butterworth polynomials.
Byte Eight bits. It takes one byte to represent one letter of the alphabet.
C Propagation velocity of sound at STP, approx. 342 m/s
Cabin Gain With a subwoofer system, the output gained within a vehicle's interior.
CAN or CAN-bus Controller Area Network (CAN or CAN-bus) is a computer network protocol and bus standard designed to allow microcontrollers and devices to communicate with each other and without a host computer. It was designed specifically for automotive applications bu
Capacitance The ability of a conductor or dielectric to store electric charge.
Capacitor 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
Capture Ratio Expressed in decibels, with the smaller the number the better. The ratio of captured signals of different strength on the same frequency.
Cas Acoustical equivalent of Cms
CD Text A compact disc and player feature utilizing disc, track, and artist information encoded directly on the CD media. Both playback and media components must have CD Text compatibility.
Chassis The metal frame of the vehicle.
Circuit Breaker A device that protects electric circuits by interrupting power in a circuit when an overload occurs. Unlike a fuse a circuit breaker is resetable. Rated in amperes (amps).
Circuit 1 Any closed path followed by electrical current. 2 A configuration of electrically or electromagnetically connected components or devices.
Clipping "Audible distortion that occurs when continuous power-to-peak power capabilities (headroom) are exceeded. ""Turn it down!"""
Closed Circuit A continuous unbroken circuit in which current can flow without interruption.
Cmes The electrical capacitive equivalent of Mms, in farads
Cms The driver's mechanical compliance (reciprocal of stiffness), in m/N
Coaxial 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)
Coherence Refering to sound quality, being aesthetically ordered, integrated and natural to the ear.
Coil (Choke, Inductor) A crossover component used to filter out higher frequencies and allow lower frequencies to pass.
Compliance The relative stiffness of a speaker suspension, specified as Vas.
Conduction The mode of heat transfer within a body or between bodies in contact with each other.
Conductivity he ability of a conductor to allow the passage of electrons, measured in the current per unit of voltage applied, shown in resistance.
Cone The most common shape for the radiating surface of a loudspeaker referred to as the part that moves the 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.
Continuity The condition of being continuous.
Cross Interleave Reed Solomon Code (CIRC)A combination of codes and interleaved data that make it possible to detect and correct errors in a compact disc system.
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.
Crossover Point Same as crossover frequency.
Crosstalk (Channel Separation) The amount of interference on one stereo channel caused by the leaking of the other stereo channel. The higher the rating in decibels (dB), the better the Channel Separation.
Current The rate of flow of electricity, measured in amperes (amps).
D Effective diameter of driver, in meters
D2D """Data to data"" connection of an alarm/remote starter to bypass module."
DAC (D/A) Digital to analog converter. A component or circuit that is used to derive or convert an analog signal from a digital one.
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 The reduction of the magnitude of resonance by the use of some type of material.
DAT Digital Audio Tape.
dBr A unit of measurement that indicates the decibel level relative to a reference level.
DC/DC Converter A group of components within an amplifier that converts battery voltage (DC) into AC so that it can be increased by the switching devices and transformer and converted back to DC (rectified) to provide higher voltage to drive the amplification stage.
Decade A measurement equal to the low pass frequency being ten times the high pass frequency, which is relevant in a passive band pass crossover. The difference between 500 Hz and 5000 Hz is equal to 1 decade.
Decibel (dB) A unit of measurement for the ratio of loudness. The threshold of hearing is 0 dB. One dB SPL is the smallest audible difference in sound level. more info
Detent Controls A detent knob has precise click-stops at regular points to indicate how much the control has been turned up or down.
Deutsche Industrie Normen (DIN) German (European) industrial standards. DIN size refers to the stereo size that fits most European automobiles.
Diaphragm A thin, semirigid membrane that vibrates to produce or transmit sound waves; the part of a loudspeaker attached to the voice coil that moves to produces sound, usually in the shape of a cone or dome.
Dielectric An insulating material with low electrical conductivity.
Diffraction A change in the direction of a sound wave that is caused by the sound wave moving past an obstacle.
Digital Output An output where the signal is in digital form to allow external processing before being converted to an analog signal.
Digital Time Delay Gain Control The control that lets you select how much of the whole of the audio signal to be treated with digital time delay.
Digital Time Delay A component that electronically delays the audio signals (in milliseconds) to provide surround type sound as well as compensate for speaker placements.
Diode An electrical circuit element that allows current to flow in one direction.
Direct Current (DC) An electrical current that flows in one direction.
Directional / Directionality The angle at which a speaker disperses sound. Higher frequencies are narrower than lower frequencies. Tweeters are more directional than woofers.
Discharge In a capacitor, the release of stored energy to a load. In a battery, the conversion of chemical energy to electrical energy.
Dispersion Distribution of sound from a speaker.
Distortion Sound that is modified or changed in some way. Measured 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.
DIY Abbreviation for Do It Yourself.
DMM Digital Multimeter. A digital meter that gives a precise reading of voltage, current, or resistance (ohms).
Dolby Digital EX Surround (Dolby Digital 6.1) Adds a rear center channel to the existing left, center, right and rear speakers. This format requires a 6.1 processor or receiver and DVDs that are 6.1 encoded.
Dolby Digital Is a five-channel system consisting of left, center, right and left rear, right rear channels. All processing is done in the digital domain. Unlike Dolby Prologic in which the rear effects channels are frequency limited to approx. 100-7000Hz, Dolby Digita
Dolby Noise Reduction A patented noise reduction system that increases dynamic range and signal-to-noise ratio of Dolby encoded media.
Dolby Prologic Is a fourchannel system consisting of a left, center, right and rear channel with the single rear channel typically played through two speakers.
Dome A convex speaker shape usually used for tweeters.
Door Lock Solenoid The proper name for the electric bi-directional actuator used to provide powered control vehicle door locks. Also called a Door Lock Actuator.
Dot Matrix Display A display type that employs regularly spaced patterned grids of point-source lighting elements. As a result, characters displayed have greater resolution than a segmented display.
Double DIN Twice the height of the standard DIN dimensions; width is standard DIN width.
DPDT Double Pole Double Throw. A term used to describe a relay that has two separate poles or contacts and can throw or make electrical contact with two separate stationary contacts.
Driver Synonymous with loudspeaker. The term also refers to a loudspeaker being coupled to a horn for acoustic coupling and controlled dispersion of sound.
DSP Digital Signal Processing (or Processor). A type of processing accomplished by a microcomputer chip specifically designed for signal manipulation, or a component using such processing. The term is often misused as a synonym for ambience synthesizer; howev
DTS Digital Theater System. A multi-channel encoding/decoding system. Used in some movie theaters and DVDs. Included in some home-theater processors and DVD players. A competitor to Dolby Digital.
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.
DVD Digital Video Disc or Digital Versatile Disc is a format of optical disc storage medium, with a greater audio-visual data storage capacity than that of the compact disc (CD) of the same dimensions.
Dynamic Noise Reduction (DNR) A signal-processing circuit that reduces the level of high frequencies (hiss). Unlike Dolby Noise Reduction, DNR does not require processing during recording.
Dynamic Range Suppression A signal compression technique which raises the level of lower passages without affecting overall volume. Especially useful with high noise levels, such as a moving vehicle.
Dynamic Range The difference between the softest and loudest portions of sound that an amplifier or recorder can reproduce within an acceptable range of distortion. Expressed in decibels, the higher the number the better.
EBP Efficiency Bandwidth Product. A guide to determine whether a loudspeaker is more suitable for a sealed or ported enclosure. EBP of less than 50 indicates the loudspeaker should be used in a sealed enclosure. EBP of 50-90 indicates flexible design options.
Effect Loop A signal path which allows an audio processor to be switched in and out of the signal path such as an equalizer.
Efficiency 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.
EL Backlight Electro-Luminescent illumination for the lighted portion of a liquid crystal display.
Electrolyte The name for the mixture of diluted sulfuric acid found in standard lead-acid vehicle batteries.
Electrolytic Capacitor A capacitor with a negative and a positive terminal that only passes alternating current.
Electromagnetic Interference (EMI) The interference caused by an electromagnetic field created by the flow of current.
Electrostatic Loudspeaker A speaker composed of two pieces of metallic foil separated by a sheet of dielectric unlike a cone and voice coil of a typical cone-type speaker.
Enclosure A box housing a speaker to separate the front sound waves from the rear sound waves.
Equalization 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).
Equalizer A component designed to alter the frequency balance of an audio signal.
ESN A cellular phone's Electronic Serial Number.
ESP Electronic Shock Protection. An electronic circuit that stores the audio data stream from a CD or MD in a memory buffer. If the laser pick-up mistracks, audio still flows from the buffer preventing an interruption.
Exa (E) A prefix meaning 1018 or 1,000,000,000,000,000,000
F3 3 dB cutoff frequency, in Hz
Fader 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.
Farad 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.
Fb Enclosure resonance (usually for bass reflex systems), in Hz
Fc System resonance (usually for sealed box systems), in Hz
FCC Federal Communication Commission. The U.S. government agency which oversees and regulates electronic communication.
Fidelity The term used to describe the accuracy of recording, reproduction, or general quality of audio processing.
Filter An active or passive circuit or device designed to block a certain frequency or range of frequencies.
Fixed DIN Mount A DIN headunit mounting system whereby no part or component is removeable for security purposes
FL Backlight Fluorescent illumination for the lighted portion of a liquid crystal display. Considered to be a step-up feature from EL backlight.
Flashing Lights A term used to describe the interfacing of the vehicle's parking lights, dome light, emergency lights, etc., with a security system so that the lights flash by the security system.
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.
Fletcher Munson Curves The set of curves showing the human's ear's frequency sensitivity versus loudness, created by researchers Fletcher and Munson. The curves show the ear to be most sensitive to sounds between 3 kHz and 4 kHz (ear canal resonances).
Floating Ground Noncommon grounding point.
Flux The flow of magnetic energy in a circuit.
FM Stereo Separation The FM tuner demodulator's ability to separate left and right channel signals of FM stereo broadcast. Measured in decibels, the higher the number the better.
Focus Lens The lens in the optical block of a compact disc player which focuses the laser light onto the surface of the disc.
Focus Servo The circuit which keeps the laser light correctly focused on the pit area of the disc.
Free Air Response The frequency at which a speaker will naturally resonate.
Frequency Dividing Network See crossover network.
Frequency Modulation (FM) The encoding of a carrier wave by variation of it's frequency in accordance with an input signal.
Frequency Response The lowest and highest parts of the frequency spectrum that can be reproduced by an audio component within specific limits and tolerances.
Frequency The number of wavelengths which pass a specific point in a specific time period, measured in Hertz (Hz). Cycles per second.
Fs "Driver free air resonance, in Hz. This is the point at which driver impedance is maximum. ""This parameter is the free-air resonant frequency of a speaker. Simply stated, it is the point at which the weight of the moving parts of the speaker becomes balanc"
Fundamental Frequency The principal component of a complex waveform having the lowest frequency.
Fuse A device that protects electric circuits by interrupting power in a circuit when an overload occurs. Rated in amperes (amps).
Fusible Link Designed to perform the same task as a fuse, but the resembles a wire. Fusible links are commonly used in ignition switches and other high current circuits.
Gain The amount of amplification used in an electrical circuit.
Gauge (wire) The diameter of a wire. The higher the number, the thinner the wire.
Giga Prefix meaning 109 or 1,000,000,000 (1 billion in the US)
Golden Ratio Two quantities are in the golden ratio if the ratio of the sum of the quantities to the larger quantity is equal to the ratio of the larger quantity to the smaller one. The golden ratio is an irrational mathematical constant, approximately 1.6180339887. A
Googol A googol is the number 10100, that is, 1 followed by one hundred zeroes.
Graphic (equalizer) Refers to a type of equalizer with sliding controls that create a pattern representing a graph of frequency response changes.
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 p
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 ot
Ground An electrical line with the same electrical potential as the chassis of the vehicle, most commonly negative 12 volts DC.
GWA Ground While Armed or Ground While Active
GWR Ground While Running
Haas Effect In 1951 Dr. Helmut Haas examined how the perception of speech is affected in the presence of a single, coherent sound reflection. In sound systems, the signal for loudspeakers placed at distant locations from a stage or intended sound stage may be delayed
Harmonic A weaker overtone or undertone of the original note responsible for the character of the note.
Head Unit (HU) The in dash control center of a car audio system. This may be any pre amp or amplified control unit such as an AM/FM/CD player.
Henry / Henries (Hy) The measurement for inductance. Coils (low pass filters) are measured in millihenries as in 6.4 mHy (6.4 millihenries).
Hertz (Hz) The unit of measurement for frequency. 1 Hz is equal to 1 cycle per second.
HID High Intensity Discharge
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.
Highs Term which refers to a set of speaker components used to reproduce frequencies above 500 Hz as in a set of separates. May also refer to tweeters which are used to reproduce frequencies usually above 2.5 kHz. Not bass.
IASCA International Auto Sound Challenge Association
ICE Acronym for In Car Entertainment
IIR Filter (Infinite Impulse Response Filter) A digital filter employing a single stage, through which the signal is passed repeatedly to achieve the desired processing effect. Offers simplicity of design and lower cost than the FIR type.
Image Rejection The rejection of the same signals that can be received at two or more points on the dial of a tuner by a single radio station (ghost, images) . Image Rejection is expressed in decibels, the higher the number the better.
Imaging 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
Impedance The opposition to the flow of alternating current (AC) in a circuit. Measured in ohms .
Inductance The ability to induce an electrical current. Measured in Henrys.
Inductive Coupling Radiated noise that is transmitted through a magnetic field to surrounding lines.
Inductor An electrical component in which impedance increases as the frequency of the AC decreases. Also known as coils that are used in passive crossovers. Inductors are rated in Hennes.
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.
Insulation A material that electrically isolates a conductor or thermally isolates an object from its surroundings.
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.
ISO-DIN Mounting Refers to a mounting system in which the headunit is mounted behind the dash panel with side brackets, employing factory installed trim panels.
Jacket The outer covering on a cable or wire that may provide electrical insulation and/or resistance to abrasion, chemicals, and moisture.
Jams Tunes, rocks, hits, sounds good, etc.
Japanese Industrial Standards Committee (JISC or JIS) A Japanese agency that establishes and maintains standards for equipment and components.
Jewel Case The hard plastic case that contains a compact disc.
Joule A unit of energy equal to one watt per second.
Junk Discarded or useless; of no value.
Kilo (k) A prefix meaning thousand.
Kilohertz (kHz) 1 kHz equals 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 stating that the voltage supplied to a DC circuit must equal the sum of the voltage drops within the circuit.
L Length of wire immersed in magnetic field, in meters
Laser Diode A semiconductor device which emits a laser beam.
LCD Liquid Crystal Display.
Lces The electrical inductive equivalent of Cms, in henries
Le """This is the voice coil inductance measured in millihenries (mH). The industry standard is to measure inductance at 1,000 Hz. As frequencies get higher there will be a rise in impedance above Re. This is because the voice coil is acting as an inductor. Co"
LED Light Emitting Diode.
Line Level The standard preamplifier output level of a signal from an audio source other than a turntable. Usually between 100mV and 1V, but may be as high as 5V or more from some preamplifiers.
Linearity Error The deviation in response from an expected or theoretical straight line value for instruments and transducers (speakers).
Linearity In an audio device, the ability to accommodate the flow of the original source signal withuot distorting or altering it in any way. A component is linear if it accurately reproduces the source signal regardless of the signal's frequency.
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.
Load The electrical demand of a process, expressed in current (amps), power (watts), or resistance (ohms).
Local / Distance Switch Changes the sensitivity of the tuner. When switched to local (LO), the stronger local stations are received with a higher image rejection. When switched to distance (DX), the weaker, distant stations are received but with less image rejection.
Loudness Control Intended to boost low frequencies at lower volume levels and should not be used at high volume listening levels.
Loudspeaker Compliance The acoustical and mechanical equivalent of capacitance. Determines how easily a speaker cone/ voice coil assembly will move when an electrical signal is applied to it.
Loudspeaker An electro acoustic transducer which converts electrical audio signals at its input to audible waves at it's output. May 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.
Lows Term which refers to a set of speaker components used to reproduce frequencies below 500 Hz as in a set of woofers. May also refer to the low frequency drivers of a set of separates. Not treble.
Magnet A device which has the ability to attract or repel pieces of iron or other magnetic material. Speaker magnets provide a stationary magnetic field so that when the coil produces magnetic energy, it is either repelled or attracted by the stationary magnet.
Magnetic Flux The magnetic lines of force produced in the area around an electric current or magnet.
Magnetic Structure The part of loudspeaker comprising the magnet, pole piece, back plate and top plate.
MECP Mobile Electronics Certification Program.
Mega (M) A prefix that means 106 (one million in the US). 1 MHz equals 1,000,000 Hertz.
Memory The word most commonly used to refer to a system's ability to retain specific information.
Micro (µ) A prefix that means 1/ 106 (one millionth in the US). 1 µV equals 1/1,000,000 of a volt.
Microprocessor A semiconductor that can be programmed to perform a variety of tasks in many different systems.
Midrange Driver A loudspeaker specifically designed to reproduce the frequencies in the middle of the audible bandwidth. Usually between three and eight inches in diameter. Commonly referred to as the low frequency driver in a set of separates.
Milli (m) A prefix that means 1/ 103 (one thousandth). 1 mA equals 1/1,000 of an amp.
Mmd Diaphram mass, in grams
Mms "The driver's effective mechanical mass (including air load), in kg. ""This parameter is the combination of the weight of the cone assembly plus the ‘driver radiation mass load’. The weight of the cone assembly is easy: it’s just the sum of the weight of th"
Monaural (mono) A sound recorded or reproduced in only one channel.
MOSFET Metal Oxide Semiconductor Field Effect Transistor. A form of field-effect transistor controlled by voltage rather than current, like a bipolar transistor. MOSFETs have a significantly higher switching speed than bipolar transistors. They generate almost n
Ms The total moving mass of the loudspeaker cone.
Multimeter A common term used to describe a VOM (voltage ohm meter). A multimeter usually has the ability to measure volts, resistance (ohms), and amperes or milliamperes.
Music 1. an art of sound in time that expresses ideas and emotions in significant forms through the elements of rhythm, melody, harmony, and color. 2. the tones or sounds employed, occurring in single line (melody) or multiple lines (harmony), and sounded or to
Mute Silent, attenuate.
n0 The reference efficiency of the system (eta sub 0) dimensionless, usually expressed as %
Nano (n) A prefix meaning 10-9 or 0.000 000 001
Noise 1 Unwanted sound of no specific frequency or amplitude. 2 Random sound of many frequencies not harmonically related (buzzing, hiss, pops, static, whine, etc.).
Nominal Impedance The minimum impedance a loudspeaker presents to an amplifier, directly related to the power the speaker can extract from the amplifier.
Normally Closed Refers to the electrical state in which a switch may rest. Its contacts are held together or closed so that current is allowed to flow through its contacts.
Normally Open Refers to the electrical state in which a switch may rest. Its contacts are held apart or open so that no current flows through its contacts.
NTSC National Television System Committee. Refers to the standards used for video broadcast and playback signal parameters.
Occupational Safety and Health Act (OSHA) The United States governmental agency that establishes and enforces safety standards in the workplace.
Octave 1. The interval of eight diatonic degrees between two musical tones. 2.The doubling or halving of frequencies.1000Hz is an octave higher than 500Hz.
Ohm The unit of electric resistance and impedance. One 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.
OSHA Occupational Safety and Health Administration. The government agency which regulates workplace safety and health.
Oversampling Doubling 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.
p rho) Density of air at STP 1.18 kg/m^3
Pa Acoustical power
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 a
Parametric A type of equalizer with adjustable parameters such as center frequency and bandwidth (Q) as well as amplitude.
Passive Arming The ability of some security systems to arm without requiring any direct action from the operator of the vehicle.
Pe Electrical power
Peta (P) A prefix meaning 1015 or 1,000,000,000,000,000
Phase The relative position of two sound waves with respect to each other.
Phase Shift Frequency interaction in the crossover region of passive crossovers which can cause some frequencies to be delayed with respect to other frequencies.
Photo Detector (photo diode) A semiconductor device which provides variations in current as a function of light intensity.
Piezo Electric Tweeter A very efficient, highly directional tweeter which operates without a crossover or magnet. Driver creates sound when a quartz crystal receives electrical energy.
Pink Noise Sound with all frequencies perceptible to the human ear reduced to an equal energy level.
Pink Noise Generator A device used to generate pink noise that usually includes a calibrated microphone.
Pinswitch A simple springloaded mechanical switch used in many different vehicles designed to turn on interior lights when doors are opened. Pinswitches are also used in the installation of most security systems in the hood or trunk/hatch as a means of triggering t
Pit One of the depressions that represents data in a compact disc. May also be referred to as bumps, this is what the pick up sees.
Plate Speaker A speaker that has two drivers mounted side by side on a flat surface.
Polarity The electrical quality of having two opposite poles, one positive and one negative. Polarity determines the direction in which a current tends to flow.
Pole Mount A common automotive speaker design with the high frequency driver mounted on a center pole. Newer designs mount the high frequency driver in the same location above the lower frequency driver with a bridge. This prevents problems such as dust and dirt fro
Potentiometer A variable resistor made with either carbon or wire wound material which attenuates a signal.
Power Handling Capability The 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 Fader A circuit that allows effective level control of two amplifiers, built in and external without loss of power.
Pre-amplifier (pre-amp) The circuit which takes a small signal and amplifies it to be fed into the power amplifier for further amplification. Contains controls for volume, regulating tone, and channel balance.
Q The relative damping of a loudspeaker
Q Parameters """Qms, Qes, and Qts are measurements related to the control of a transducer's suspension when it reaches the resonant frequency (Fs). The suspension must prevent any lateral motion that might allow the voice coil and pole to touch (this would destroy the l"
Qa The system's Q at Fb, due to absorption losses; dimensionless
Qec The system's Q at resonance (Fc), due to electrical losses; dimensionless
Qes "The driver's Q at resonance (Fs), due to electrical losses; dimensionless. ""A measurement of the control coming from the speaker's electrical suspension system (the voice coil and magnet). Opposing forces from the mechanical and electrical suspensions act"
Ql The system's Q at Fb, due to leakage losses; dimensionless
Qmc The system's Q at resonance (Fc), due to mechanical losses; dimensionless
Qms "The driver's Q at resonance (Fs), due to mechanical losses; dimensionless. ""A measurement of the control coming from the speaker's mechanical suspension system (the surround and spider). View these components like springs."""
Qp The system's Q at Fb, due to port losses (turbulence, viscousity, etc.); dimensionless
Qtc The measurement of a speaker and enclosure working together as one. The system's Q at resonance (Fc), due to all losses; dimensionless
Qts "The measurement of the speaker as a motor taking into consideration all mechanical and electrical losses. The driver's Q at resonance (Fs), due to all losses; dimensionless. ""The 'Total Q' of the driver and is derived from an equation where Qes is multipl"
Quantization The assigning of values to discrete samples of a continuous signal in the analog to digital conversion process.
R Ripple, in dB
Radio A head unit that combines a tuner, a preamplifier, and a power-amplifier.
Radio Frequency Interference (RFI) Electromagnetic waves between the frequencies of 10 KHz and 300 GHz that can affect susceptible systems by conduction through sensor (tape head) or power input lines, and by radiation through space.
RAM Random Access Memory. A memory device that one can write data to and read data from.
Ras Acoustical equivalent of Rms
Re """This is the DC resistance of the driver measured with an ohm meter and it is often referred to as the 'DCR'. This measurement will almost always be less than the driver's nominal impedance. Consumers sometimes get concerned the Re is less than the publis"
Relay (SPDT) (Single Pole Double Throw Relay) an electromagnetic switch, consist of a coil (terminals 85 & 86), 1 common terminal (30), 1 normally closed terminal (87a), and one normally open terminal (87).
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"
Res The electrical resistive equivalent of Rms, in ohms
Resistance The opposition to the flow of AC or DC voltage in an electric current. Measured in ohms.
Resistor An electrical device that resist the flow of electrical current. The higher the value of resistance (measured in ohms) the lower the current will be.
Resonance Pitch. When you tighten a drum, you raise it's 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.
Revc DC voice coil resistance, in ohms
Revc DC voice coil resistance, in ohms
RF Modulator A device that converts a signal (typically audio and/or video) into a radio frequency.
Rg Amplifier source resistance (includes leads, crossover, etc.), in ohms
Rg Amplifier source resistance (includes leads, crossover, etc.), in ohms
Rms """This parameter represents the mechanical resistance of a driver’s suspension losses. It is a measurement of the absorption qualities of the speaker suspension and is stated in N*sec/m."" The driver's mechanical losses, in kg/s"
RMS Root Mean Square.
Roll-Off Relates to the attenuation of frequencies, above or below a given point, at a specific rate.
ROM Read Only Memory. A memory device that one can only read data from. The data has been pre-programed.
Sabine Unit of measurement for absorption. One sabine is equal to the absorption of 1 square foot of surface which will absorb all incident energy.
Sampling Measuring the analog signal at a fixed rate of speed (sampling frequency).
Sd "Effective piston radiating area of driver, in square centimeters. ""This is the actual surface area of the cone, normally given in square cm."""
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.
Selectivity (alternate channel) Similar to capture ratio, but deals with signals which are broadcast on frequencies very close to the one selected.
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.
Separates 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).
Separation 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 , connecting the negative terminal of # 1 to the positive termi
Shield A metallic foil or braided wire layer surrounding conductors which is designed to prevent electrostatic or electromagnetic interference from external sources.
Signal Any electrical transmittance that conveys data.
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 10.0 dB 20.0 dB 30.0 dB 40.0 dB 50.0 dB 60.0 dB 70.0 dB 80.0 dB Times Signal is Greater than Noise 3.16 10.00 31.62 100.00 316.
Slope The rate of boost or attenuation expressed in decibels of change per octave.
Sound A wave propagated in air producing an auditory sensation in the ear by the change of pressure at the ear.
Sound Field The total acoustical characteristics of a space, such as ambience [number, timing, and relative level of reflections (ratio of direct to reflected sound)].
Sound Pressure Level (SPL) An acoustic measurement of sound energy, typically expressed in dB SPL.
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.
SPDT Single Pole Double Throw. A relay that has only one pole or contact but whose contact can throw or make electrical contact with two separate stationary contacts.
Speaker A transducer which converts electrical energy into acoustical energy (sound).
Spectrum Analyzer A device that displays a frequency response curve, in real time, as the curve, changes.
SPST Single Pole Single Throw. A relay that has only one pole or contact and can only throw or make electrical contact with one stationary contact.
Standing Waves Created when two waves in opposite directions interfere. When a reflected wave reinforces a reflection of the original waveform, the sound waves reinforce themselves, increasing in altitude.
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.
Sub Harmonic The result of the division of the fundamental frequency by the desired number harmonic. The sub harmonic of 1000 Hz is 500 Hz.
Subwoofer A loudspeaker made to reproduce the lowest of audio frequencies, approx. 25 Hz to 125 Hz.
Subcode Data, other than music, which is stored on a CD, MD, or other digital format. Used to indicate track number, index number, use of emphasis, and other information.
Supertweeter A high frequency driver designed to reproduce very high frequencies, typically over 10 kHz.
Switch A switch is any form of mechanical, electronic, electromechanical, magnetic, or mercury device that either opens or closes a circuit
Tera (T) A prefix meaning 1012 or 1,000,000,000,000 (one trillion in the US).
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.
TOC / Table Of Contents The subcode information which contains track numbers and times.
Toroidal Coil An inductor or transformer whose core consists of a concentrically wound ribbon of magnetic material. Also used to filter noise on a DC supply line.
Total Harmonic Distortion (THD) The noise referenced to signal in decibels (dB) as a percentage. Noise referenced to Signal -10.0 dB -20.0 dB -30.0 dB -40.0 dB -50.0 dB -60.0 dB -70.0 dB -80.0 dB Percent Distortion 31.6% 10.0% 3.16% 1.00% 0.316% 0.100% 0.0316% 0.0100%
Tracking Servo The control circuit used to keep the pick-up over the desired track.
Transducer A device used to convert energy from one form to another. Acoustical to electrical (microphone), electrical to acoustical (speaker), and electrical to mechanical (Aura Bass Shaker) are three examples of transducers.
Transformer An electrical device that can be used to provide circuitry isolation, signal coupling, impedance matching, or voltage step-up .
Transistor A three terminal device used for amplification and switching.
Tuner A component (or section of one) that receives radio signals and selects one broadcast from many.
Tweeter A high frequency driver specifically designed to reproduce only the high frequencies (treble) of the audible spectrum.
Underlap The crossover point being more than 3 dB below the unattenuated level.
Unloading 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.
Vas Compliance. A measurement in liters or cubic feet of the volume of air that is equal to the compliance of the speaker's total suspension.
Vas/Cms """Equivalent volume of compliance"", this is a volume of air whose compliance is the same as a driver's acoustical compliance Cms (q.v.), in cubic meters. ""Vas represents the volume of air that when compressed to one cubic meter exerts the same force as the"
Vb Net enclosure volume.
Vd "Maximum linear volume of displacement of the driver (product of Sd times Xmax), in cubic meters. ""This parameter is the Peak Diaphragm Displacement Volume — in other words the volume of air the cone will move. It is calculated by multipying Xmax (Voice Co"
Voice Coil Coil of wire wrapped around a tube and attached to the speaker cone or driver diaphragm. Becomes an electromagnet when an audio signal is applied and interacts with a permanent magnet which causes the cone or diaphragm to vibrate.
Volt The unit of measure for electrical potential.
Voltage Drop The amount of energy consumed when a device has resistance in its circuit. The voltage (E) set up across a resistance (R) carrying a current (I); E=IR
Voltage he difference in electrical potential between two points in a circuit. It's the push or pressure behind current flow through a circuit.
VOM Volt-Ohm-Meter. A multimeter that measures voltage, resistance (ohms), and amperes, milliamperes
W2W """Wire to wire"" connection of an alarm/remote starter to bypass module."
Watt (wattage) A measurement of real power. The product of voltage and current in a resistive circuit.
Wavelength The length of distance a single cycle or complete sound wave travels.
White Noise Noise in which a constant energy level per unit (1 Hz) is maintained in all frequencies.
Woofer A loudspeaker made to reproduce the lower range of the audio spectrum (bass), in a 2-way or more complex speaker system.
Wow and Flutter Usually refers to the inconsistencies in tape speed which cause pitch variations and quivering sounds. Wow is slow-speed variations, and flutter is fast-speed variations. Expressed as a percentage, with lower numbers being better.
XM Radio XM Radio broadcasts 100 channels of totally new music, news, sports and children's programming direct to cars and homes via satellite an extensive repeater network, which supplements the satellite signal to ensure seamless transmission. The channels origi
Xmax/Xmech "Maximum peak linear excursion of driver, in meters. ""Short for Maximum Linear Excursion. Speaker output becomes non-linear when the voice coil begins to leave the magnetic gap. Although suspensions can create nonlinearity in output, the point at which the"
Yocto (y) A prefix meaning 10-24 or 0.000 000 000 000 000 000 000 001
Yotta (Y) A prefix meaning 1024 or 1,000,000,000,000,000,000,000,000
Zepto (z) A prefix meaning 1021 or 0.000 000 000 000 000 000 001
Zero Bit Detection A circuit in a D/A converter that monitors the digital audio bit stream. upon encountering all bits low, or zero bits, the output of the D/A is disconnected from the preamp. This improves the signal-to-noise ratio specification.
Zero Output The absence of output signal or output power.
Zetta (Z) A prefix meaning 10-21 or 1,000,000,000,000,000,000,000
Zmax This parameter represents the speaker’s impedance at resonance
Zobel A filter used to stabilize speaker impedance at a crossover frequency where impedance has risen to twice the nominal impedance.
Zone A specific area of a security system's coverage. A specific trigger input of an alarm.