Back Plate - The part of a woofer Basket or Frame on which the Magnet structure is mounted (click here for Speaker parts diagram).

Back Light - Lighting a display from the rear for better visibility under a wide range of ambient light conditions.

Back-up Battery - A separate battery added to the security system as an alternate power supply, serving as a backup in case the vehicle's main battery should be disabled by a thief.

Baffle - A flat panel that separates the front and rear sound waves produced by a woofer. Also can be part of an enclosure (the surface on which the speaker is mounted).

Balanced Line - Style of interconnect used for noise rejection. These do not use the cable's Shield (outer foil or wire casing around inner signal wires) for a ground as standard interconnects do. Each signal path has it's own ground wire along with a positive wire of the same impedance twisted inside a shield. Balances lines are the preferred method for interconnecting commercial or high-end sound systems because of their superior noise immunity.

Bandpass filter - A filter that only allows a certain range, between a high and low point, of frequencies to pass through it. In multi-driver speaker systems, the Midrange driver may be fed by a bandpass filter.

Bandpass Enclosure - For details and more enclosure types see Woofer Enclosure Designs.

Bandwidth (BW) - A range, or band of audio frequencies between an upper and lower point.

Barium Ferrite - An alloy comprised of iron and barium for improved magnetic strength that's used in speaker magnets.

Basket - The metal frame structure of a standard dynamic loudspeaker. This may be made of stamped steel or cast metal for extra strength and rigidity. All the other elements of the speaker are mounted on this structure (click here for Speaker parts diagram).

Bass Boost/Enhancer Circuit - An active low pass section added to some receivers, equalizers, and amplifiers that allows as much as an 18 decibel boost to be applied to an audio signal in the low frequency 35 to 90 Hertz range.

BBE Processing - A signal processing circuit that provides improvements in spatial realism and imaging by altering the frequency and phase characteristics of certain portions of the input signal.

Bi-Amplification - Some speaker systems with multiple drivers do not contain a crossover network so they require a separate amplifier for each frequency range and the speakers associated with it. The bi-amplified system still requires an active crossover to send the proper frequency band to each amplifier and speaker network.

BIT - A Binary Digit. The smallest unit of data in a digital signal represented by a value of either one or zero.

BL (a Theile Small parameter ) - The magnetic strength of a speaker's motor structure.

Bridged Power - Bridging an amplifier, combines the power output of two channels into one channel. If the amp is bridgeable, the owner's manual will have directions that tell you how. Bridging will allow an amp to produce more overall power, but it also treats the impedance load (Ohms) as if it is cut in half (ie: a 2 ohm load seems like a 1 ohm load to the amp). Keep this in mind to avoid shutting down or damaging you amp.

BTL (Bridged, Transformer Less) - An amplifier output circuit design that allows two smaller Integrated Circuit (IC) amp channels to be bridged together to provide a single, larger output circuit. These circuits are limited by the current available to them, their current capabilities and the amount of heat they generate.

Bel - The Bel (In honor of Alexander Graham Bell) was originally a unit measure of the amount a signal dropped in level over a one-mile distance of telephone wire. (Also see decibel)

Buffer - Commonly used in DVD and CD players, this device protects against vibrations reading ahead before generating an output signal and storing the audio data for uninterrupted playback. Data is available from the buffer when it can not be read from the disc (unless the playback interruption exceeds the playback time of the data stored in the buffer).

Butyl - A rubber composition used for speaker surrounds. Butyl is resistant to UV contamination from the sun and has very good damping characteristics.

Butterworth Crossover - A type of crossover circuit utilizing low-pass filter design characterized by having a very flat (little deviation) response in it's frequency range.