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C3 Customs
120 S. Alexander Suite #7
Baytown TX 77520
832-892-8077
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Audio Definitions
A-F
A:
AC (Alternating Current): An electrical current that periodically changes in magnitude and direction.
Acoustic Fiberglass:: Thin fiberglass material used as damping material inside speaker enclosures.
Acoustics: The science or study of sound.
Air Gap: The space between the top plate and the pole piece. This is where the voice coil sits.
Alignment: A class of enclosure parameters that provides optimum performance for a woofer with a given value of Q.
Alpha: In sealed enclosure designs, the ratio of Vas to Vb, where Vb is the volume of the box you will build.
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.
Ampere (A): The unit of measurement for electrical current in coulombs per second. There is one ampere in a circuit that has a one ohm resistance when one volt is applied to the circuit.
Amplifier: An electrical circuit designed to increase the current, voltage, or power of an applied signal.
Amplitude: The relative strength (usually voltage of a signal). Amplitude can be expressed as either a negative or positive number, depending on the signals being compared.
Attenuation: The reduction, typically by some controlled amount, of an electrical signal. 2. loss of dB.
Audio Frequency: The acoustic spectrum of human hearing, generally regarded to be between 20 Hz and 20 kHz.
B:
B:Magnet flux density in gap.
Baffle: A board or other plane surface used to mount a loudspeaker.
Balance: Equal strength provided to both left and right stereo channels.
Bandwidth: The range of frequencies covered by a driver or a network (crossover).
Band-Pass Enclosure: Type of enclosure used for subwoofers where the driver is completely inside the enclosure and all of the output emerges through a port(s) on one of the sides. They are difficult to calculate for optimum performance.
Band-Pass Filter: An electric circuit designed to pass only a certain range of frequencies.
Basket: The metal frame of a speaker.
Bass Blockers: First order high-pass crossover (non-polarized capacitors), generally used on midbass or dash speakers to keep them from trying to reproduce deep bass which could damage them at high playing levels.
Bass Frequencies (Low Frequencies): The low end of the audio frequency spectrum. There are no real frequencies where bass is categorized, but it ranges from approximately below 20 Hz to 400 Hz.
Bi-amping: Means that instead of driving a speaker full-range with a single channel of amplification, through a single set of speaker cables, you actually connect two sets of cables, with each set driven by a separate amplifier, or separate channels of a multi-channel amplifier. This way, low frequencies and high frequencies each receive dedicated amplification.
Bi-wiring: Involves connecting two sets of cables to your speakers, like bi-amping, but both sets of cables connect to the same set of output connectors on your receiver or amplifier. Bi-wiring doesn't deliver more watts to your speakers, so it doesn't offer the dramatic sonic improvement and higher loudness capability of bi-amping.
BI: Electro-magnetic force factor.
BL: Driver motor strength.
Boomy: The smearing of transients that makes bass reproduction sound muddled, usually because of improperly designed sealed (too small), ported (to small or tuned improperly), and band-pass enclosures, although the latter are sometimes designed this way on purpose by car audio manufacturers or install shops to be loud.
Bridged: In a multi-channel amplifier, the connection of two channels to drive a single load.The input signal is split, and then the phase of one of the signals is inverted. The non inverted signal is sent to the left amplifier and the inverted signal is sent to the right amplifier (L+R-). The load is connected between the two outputs so it receives twice the voltage at a given input level. The resultant power is much greater than the two 4-ohm channels combined.
C:
C: Propagation velocity of sound at STP, approx. 342 m/s (meters per second).
Cab: Acoustic compliance of air in an enclosure.
Cabin Gain: The low frequency boost normally obtained inside a vehicle interior when subs are properly mounted.
Capacitor: An electronic device, which stores energy and releases it when needed. Also used to direct high frequency energy to tweeters. (Rated in Farads)
Cas: Acoustical equivalent of Cms.
Center Channel: In home theater, sound decoded from the stereo signal sent to a speaker mounted in front of the listener. Specially designed to enhance voices and sound effects from a movie soundtrack or other audio recording with enhanced features. Used in car audio to help offset skewed stereo imaging due to seating positions in the automotive environment.
Channel: The path an audio signal travels through in a circuit during playback. At least 2 channels are required for stereo sound.
Circuit: A complete path that allows electrical current from one terminal of voltage source to the other terminal.
Circuit Breaker: An electromechanical device designed to quickly break its electrical connection should a short circuit or overload occur. A circuit breaker is similar to a fuse, except it will rest itself or can be manually rested, and will again conduct electricity.
Class A: The amplifier conducts current throughout the entire cycle (360). The Class A design is the most inefficient and is used in low-power applications as well as in very high-end stereo. Such devices may be as little as 15% efficient, with 85% of the energy wasted as heat.
Class B: The current flows only 180¼ for half the cycle, or two transistors can be used in a push-pull fashion, each one operating for 180¼. More efficient than Class A, it is typically used in low-end products.
Class AB: Combines Class A and B and current flows for 180¼ to 200¼. Class AB designs are the most widely used for audio applications. Class AB amplifiers are typically about 50% efficient but can be as high as 60%.
Class C: Operating for less than half of one wave cycle (100¼ to 150¼), Class C amplifiers are the most efficient, but not used for audio applications because of their excessive distortion.
Class G: A variation of the Class AB design that improves efficiency by switching to different fixed voltages as the signal approaches them.
Class H: An enhancement of the Class G amplifier in which the power supply voltage is modulated and always slightly higher than the input signal.
Class D: Class D is a digital-like amplifier that works by turning a transistor fully on or off, but the "D" technically does not stand for digital.
Definition of Class D amplifier:An audio amplifier that works in the digital domain. It generates the equivalent analog output for the speakers by using pulse width modulation (PWM) or pulse density modulation (PDM) rather than the traditional digital-to-analog conversion. See PWM and PDM.
Less Heat than Analog: Because pulse modulation output signals are either on or off, Class D amplifiers produce far less heat than analog amplifiers. Reaching efficiencies greater than 90% compared to only 50% for analog, they are widely used for every amplification requirement from cellphone speakers to high-end stereos.
Digital and Analog: Class D was not coined for "digital;" it was the next letter after Class C. However, it does produce a "digital-like" output because the signals are generated by turning a switch fully on or off. But it is not technically digital because the output is not digital data. It is a modulated audio signal that is feeding analog speakers and is equivalent to the output of a traditional analog amplifier. Some call this a "synthesized analog" output. See amplifier classes.
Class T: A variation of the Class D technique from Tri-path. Class T modulates the pulses based on the individual characteristics of the output transistor.
Clipping: The distortion that occurs when a power amplifier is overdriven. This can be seen visually on an oscilloscope, when the peaks of a waveform are flattened, or "clipped" at the signal's ceiling.
Cmes: The electrical capacitive equivalent of Mms.
Cms: Mechanical suspension compliance of a driver consisting of the spider and surround.
Coaxial Driver: A speaker composed of two individual voice coils and cones; used for reproduction of sounds in two segments of the sound spectrum. Usually used in automotive speakers.
Compliance: The relative stiffness of a speaker suspension, specified as Vas.
Cone: The cone-shaped diaphragm of a speaker attached to the voice coil, which produces pulses of air that the ear detects as sound. Some subs are now made with flat pistons instead of a cone shape.
Coulomb: An amount of electrical charge, which contains 6.24 x 10^18 of electrons.
Crossover Frequency: The frequency at which a driver is crossed over at, usually when response is down -3dB.
Current (I): The flow of electrical charge measured in amperes.
D:
D: Effective diameter of driver.
Daisy Chain: The wiring of multiple amplifiers together using the line out wiring options on the amps.
Damping: The reduction of movement of a speaker cone, due to either the electromechanical characteristics of the speaker driver and suspension, the effects of frictional losses inside a speaker enclosure, and/or by electrical means.
Damping Material: Any material added to the interior of a speaker enclosure to absorb sound and reduce out-of-phase reflection to the driver diaphragm (cone). Usually acoustic fiberglass, Polyester batting, or poly-fill is used in speaker enclosures.
DC (Direct Current): A flow of electrons, which travels in one direction only.
Delay: The amount of time, usually in milliseconds (ms), that a signal processing unit adds to a channel of music. This is usually used to delay the rear channels with respect to the front channels to give a sense of greater space.
Decibel (dB): (1) A logarithmic scale used to denote a change in the relative strength of an electric signal or acoustic wave. It is a standard unit for expressing the ratio between power and power level. An increase of +3 dB is a doubling of electrical (or signal) power; an increase of +10 dB is a doubling of perceived loudness. The decibel is not an absolute measurement, but indicates the relationship or ratio between two signal levels. (2) SPL (sound pressure level) can be measured in dB. 0 dB represents the threshold of normal human hearing, 130 dB represents the threshold for pain.
Diaphragm: The part of a dynamic loudspeaker attached to the voice coil that moves and produces the sound. It usually has the shape of cone or dome.
Diffusion: The scattering of sound. Diffusion reduces the sense of direction of sound source, a useful quality in surround speakers.
Dispersion: The spreading of sound waves as it leaves a speaker.
Displacement: The measurement of cubic volume that an item (such as a speaker or port) takes away from the internal volume of an enclosure, when designing an enclosure this figure must be added to the enclosure volume.
Distortion: Any undesirable change or error in the reproduction of sound that alters the original audio signal or recording.
Dome Tweeter: A high frequency speaker with a dome-shaped diaphragm, usually small in size.
Dual Voice Coil (DVC): A voice coil with two windings, generally subwoofers. Each voice coil can be connected to a stereo channel, or both voice coils can be wired in parallel or series to a single mono channel. If connecting to stereo channels it is important that each channel have the same audio signal input so that 2 channels have the same output and both voice coils work in unison.
Driver: A loudspeaker unit, consisting of the electromagnetic components of a speaker, typically a magnet and voice coil.
Driver Parameters: The physical properties of a driver that determine it's electrical and acoustical behavior. Also called thiele small parameters. The minimum parameters used in determing speaker enclosures are Fs, Qts, and Vas.
DSP: Standing for digital signal processing it is most commonly found in processing units to recreate or simulate a specific acoustic environment. Many older units used this technology to recreate venues like a concert hall or a disco club.
Dust Cap: Part of the speaker that keeps foreign material from falling into the voice coil, which could hinder the speakers movement and cut short its life.
Dynamic Range: Expressed in decibels, the range of signals amplitude (from the loudest to the quietest) that can be reproduced effectively by a piece of equipment. With respect tp amplifiers, this range is defined by inherent noise at low levels and by overload distortion at high levels. The higher the number, the better the performance.
E:
EBP: Efficiency Bandwidth Product. A rating that helps a builder determine whether a driver is suitable for a sealed or ported enclosure. EBP of less than 45 indicates the driver should be used in a sealed, 45 - 65 indicates flexible design options, over 65 indicates best for a ported enclosure. This only gives us a general idea what type of box to use. With actual testing the subs, sometimes EBP does not prove 100% accurate.
EBP = Fs/Qes.
Efficiency Rating: The loudspeaker parameter that shows the level of sound output when measured at a prescribed distance with a standard level of electrical energy fed into the speaker.
Electronic Crossover: Uses active circuitry to send signals appropriate drivers. This is more efficient than passive crossovers.
Enclosure: The box that contains the driver(s).
Equalizer: Electronic device used to boost or attenuate certain frequencies.
F:
F3: The roll-off frequency at which the driver's response is down 3dB's from the level of it's mid-band response, sometimes called the cutoff frequency.
Fb: The tuned frequency of a ported box.
Fc or Fcb: The system resonance frequency of a driver in a sealed box.
Fs: The frequency of resonance for a driver in free air.
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.
Filter: Any electrical circuit or mechanical device that removes or attenuates energy at certain frequencies.
Flat Response: The faithful reproduction of an audio signal; specifically, the variations in output level of less than 1 dB above or below a median level over the audio spectrum.
Free Air Resonance: The natural resonant frequency of a driver when operating outside an enclosure.
Frequency: The number of waves (or cycles) arriving at or passing a point in one second, expressed in hertzs (Hz).
Frequency Response: The frequency range to which a system, or any part of it, can respond. Unless a limit of variation in intensity is stated, this specification is meaningless.
Full-range: A speaker designed to reproduce all or most of the sound spectrum.
Audio Definitions are subject to change without notice.
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