Back Light - Audio

In receivers, a display may be lit from the rear to create better visibility under a wide range of ambient light conditions.

Back Plate - Audio

The part of the woofers metal Basket or frame on which the Magnet structure is mounted.

Baffle

A flat panel that divides the front and rear sound waves produced by a woofer. Sometimes baffle is used to mean an enclosure or the front panel that the speaker is mounted on.

Balanced Input

An input which compares the negative and positive sides of the signal, used to help eliminate noise.

Balanced 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 connectors. Balanced lines are less apt to pick up external noise. This is usually not a factor in home audio, but is a factor in professional audio requiring hundreds or even thousands of feet of cabling. Many higher quality home audio cables terminated with RCA jacks are balanced designs using two conductors and a shield instead of one conductor plus shield.

Bandpass Filter

In mobile electronics, a device which incorporates both high-pass and low-pass filters in order to limit and attenuate both ends of the frequency range.

Bandpass Gain

The increase (or decrease) in efficiency of loudspeakers, due to the enclosure size and tuning. This is measured by the midband sensitivity of the speaker as a whole.

Bandwidth

Refers to the "space" in the frequency response of a device through which audio signals can pass (between lower and upper frequency limits, those points where the signal level has rolled off 3 dB).

Barium Ferrite

A speaker magnet material made from an alloy with iron and barium for improved magnetic strength

Basket

The metal frame structure of a standard dynamic loudspeaker. In larger, heavier speakers, this may be made of cast metal for extra strength and rigidity. All the other elements of the speaker are mounted on this structure.

Bass

The part of the frequency range made up of the low frequencies. Bass is generally agreed to be those frequencies between 20 Hz and 400 Hz.

Bass Blockers

Commercial name for auto-sound first order high pass crossovers (non-polarized capacitors), generally used on midbass or dash speakers to keep them from trying to reproduce deep bass.

Bass Boost Circuit

Used in car audio amps to allow for additional control of response in a specific vehicle. These are usually centered at 40Hz and provide up to 6dB of gain.

Bass Reflex

A low-frequency loudspeaker enclosure design in which the volume of the enclosure and the dimensions and shape of a vent, or port, form a Helmholtz resonance which is designed to integrate with the performance parameters of a woofer. Such systems are characterized by increased acoustical output at certain frequencies near the system resonance, less output at lower frequencies, and the potential for reduced distortion at high sound levels.

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 Alignment

A particular crossover configuration which offers superior phase coherence in exchange for slightly lower level match.

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 it reproduces a near-perfect step response with no overshoot or ringing. The downside of the Bessel is a slow roll-off rate. The same circuit complexity in a Butterworth response rolls off much faster.

Bi-Amplification

Some speaker systems with multiple drivers do not contain a crossover network, and they require a separate amplifier for each frequency range. The bi-amplified system still requires an active or passive crossover network to send the proper frequency band to each amplifier and speaker, but it precedes the amplifier and speaker and does not handle the power amplifier output.

Bias

An unbalanced sound level.

Bipolar Transistor

A transistor that contains two" positive" or "negative" junctions or diodes between two layers of opposite polarity material.

Blank Skip

A cassette feature that automatically detects blank areas of the tape over 8 seconds in length and activates Fast Forward, until the end of either the tape or audio information is reached.

Boomy

Usually refers to excessive bass response, or a peak in the bass response of a recording, playback or sound reinforcement system.

Boprene

A type of butyl rubber surround that has excellent damping characteristics and is extremely environmentally stable. .

Bridging

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.

BSSM

Best Stations Sequence Memory .

BTL

Bridged Transformer Less - 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.

Butterworth Filter

A filter with a pass-band with no ripple but usually sacrifices some steepness in attenuation.

Butyl

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