Audiogearreviews.com Glossary

Glossary A-E

AM
Amplitude Modulation. A method of radio transmission which sends information as variations of the amplitude of a carrier wave.

AM Presets
Preset memories for AM radio stations.

Amperage
The rate of flow of electricity through wire - measured in terms of amperes.

Ampere
The measurement of the flow of an electric current through a conductor.

Amplifier (Audio)
A device that increases the output level of the signal it receives without changing the sonic characteristics of that signal. While typically used to describe a device that drives speakers (transducers) it does define any device that increases the level of the audio input signal.

Amplitude
The measure of how powerful sound waves are in terms of pressure or voltage.

Analog
Continuously variable audio signal that can take on any value within a given range.

Attenuation
The process of weakening or reducing the amplitude of a audio signal.

Audio Bandwidth
The audible frequency range of human hearing

Back Plate
The back of the speaker that is connected to the magnet and provide the return path for the magnetic energy of the motor structure.

Back Plate (Bumped)
See Bumped Back Plate

Balanced Inputs
See differential inputs

Basket (Speaker)
The part of the speaker (transducer) that supports the motor structur in a static position and keeps the drive elements in a pistonic movement path.

Battery
The power storage device in the vehicle. It starts the vehicle and provides power for the accessories like your car audio system.

Battery (B-)
The ground terminal post of the battery.

Battery (B+)
The positive termial post of the battery. It also refers to the electrical connection that is always energized with 12 volts + from the battery.

Bl
The motor strength of a speaker (transducer) in the magnetic gap. The strength is a result of the magnet material used, the configuration of the motor structure and the size of the magnetic gap. Measured in Teslas.

Bottom Plate
The plate located on the bottom of the magnet in a speaker (transducer) that provides the magnetic return path for the motor structure. It is also connected to the pole piece. (The Bottom plate and pole piece can be the same unit)

Bumped Back Plate
A back plate that has a bumped construction to increase clearance for the voice coil former that allows for greater excursion.

Capacitance
That property of a system of conductors and dielectric, which permits the storage of electricity when potential difference exists between the conductors.

Capacitor
An electronic device which stores energy and releases it when needed. Also used to direct high frequency energy to tweeters. Rated in Farads.

CD
Developed by Philips and Sony, the compact disc was first commercially implemented digital medium for storing digital audio data. The physical size of the disc is 12 cm and store up to 700MB of data.

Class A
Amplifier operation where both output devices conduct continuously for the entire cycle of signal swing, or the bias current flows in the output devices at all times. In class A operation, both upper and lower output devices are always on. Class A is the most inefficient of all power amplifier designs, averaging only around 20% amplifier efficiency.

Class AB
A combination of Class A and Class B operation that combines the efficiency of Class B with the reduced crossover distortion created by the transition between the upper and lower output devices. Typical good Class AB amplifiers average between 50-60% amplifier efficiency.

Class B
Amplifier operation where only the upper or lower output device is operating at one time. Class B is more efficient than Class A but suffers from crossover distortion where the transition of the upper and lower output devices transition.

Class D
An amplifier configuration where the output devices are digitally controlled and pulsed on and off to generate the audio output signal. This is an extremely efficient design that averages 70-80% amplifier efficiency. The short fall is the difficulty in accurately producing high-frequency audio signals. As a result, most Class D amplifiers are designed for subwoofer use.

Class T
An proprietary amplifier configuration that operates digitally like Class D but switches at ultra-high frequency allowing for full range operation.

Cms
The speaker's (transducers) mechanical compliance (reciprocal of stiffness) measured in mm/N.

Coaxial Speakers
A speaker combination where two speakers (tranducers), optimized for different frequency ranges, are mounted in a coaxial arrangement. Also includeds speakers with more than two speakers.

Component Speakers
A speaker set where the tweeter, midrange and midbass (if included) are separate and mounted individually.

Crossover
An audio device that separates the audio signal into two or more bands for reproduction by different speakers

Crossover (Bandpass)
A device, circuit or algorithm that combines the functionality of a high-pass and low-pass crossovers to allows a band of frequencies to pass through while filtering (blocking) out frequency above and below the pass band.

Crossover (Digital)
A crossover that filters the audio bandwidth with algorithms in the digital domain. It is located between the digital decoding of a CD or DVD and the analog converted output.

Crossover (Electronic)
A crossover that separates the audio signal in the pre-amplifier stage. It can be a stand alone device or incorporated in an amplifier, signal processor or source unit.

Crossover (High-pass)
A device, circuit or algorithm that allows higher frequencies to pass while filtering out (blocking) lower frequencies.

Crossover (Low-pass)
A device, circuit or algorithm that allows lower frequencies to pass while filtering out (blocking) higher frequencies.

Crossover (Passive)
A crossover that filter the audio bandwidth of a speaker. This device is located between the amplifier and the speaker.

Crossover Point
The frequency point at which the crossover affects or filters the audio signal.

Current Draw
The amount of current of an electrical device from vehcile's electrical system.

Damping Efficiency
The ability of a damping material to control vibration.

Damping Factor
The ability of the amplifier to control the movement of a speaker (transducer). It is the ratio between the speaker's impedance and the output impedance of the amplifier.

dB (Decibels)
Units of the measure of loudness. Decibles is the loudness of 1/10 of a bell right. This is a logrithmic scale.

Detachable Face
The removeable part of the source unit's face plate.

Differential Inputs
An audio signal delivery system that reduces noise. For each input signal there are two signal wires. A third connector allows the signals to be referenced to ground. The audio output is the difference in voltage between the two wires: any voltage (noise) common to both wires is removed.

Digital
The method of storing, processing and transmitting information through the use of distinct electronic or optical pulses that represent the binary digits 0 and 1.

Digital Ready
A marketing term to make customers think that speakers and amplifiers are capable of dealing with the dynamics of a digital source.

DIN
DIN, (a German Institute for Standardization) used to describe the stardard size of radio mounting location is vehicle

Dome (Speaker)
A speaker (transducer) with a diaphragm that is shaped like a dome. Dome speakers area usually tweeters but can also be midranges. The dome can be either concave or convex.

DVD
Digital Video Disc. Capable of storing 4.7 GB or 8.5 GB for single or dual layers respectively.

Efficiency (Acoustic)
See No

Efficiency (Amplifier)
The ratio between the amounts of power consumed versus the amount of power produced. Efficiency depends on many factors, including but not limited to, battery voltage, amplifier load and impedance load of the speakers.