Car Audio Dictionary:

A: Attenuation, loss of dB. 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.

Audio Frequency: The acoustic spectrum of human hearing, generally regarded to be between 20 Hz and 20 kHz. 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 optium 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 seperate channels of a multi-channel amplifier. This way, low frequencies and high frequencies each receive dedicated amplification.