Glossary of Audio Terms

AC.. Abbreviation for alternating current.

Active crossover.. Uses active devices (transistors, ICs, tubes) and some form of power supply to operate.

Amplitude.. The extreme range of a signal. Usually mea- sured from the average to the extreme.

Arc.. The visible sparks generated by an electrical dis- charge.

ATF.. The abbreviation for advanced thin film.

Bass.. The lowest frequencies of sound.

Bi-Amplification.. Uses an electronic crossover, or line- level passive crossover, and separate power amplifiers for the high and low frequency loudspeaker drivers.

Capacitance.. That property of a capacitor which determines how much charge can be stored in it for a given potential difference between its terminals, measured in farads, by the ratio of the charge stored to the potential difference.

Capacitor.. A device consisting of two or more conducting plates separated from one another by an insulating mate- rial and used for storing an electrical charge. Sometimes called a condenser.

Clipping.. Distortion of a signal by its being chopped off. An overload problem caused by pushing an ampli- fier beyond its capabilities. The flat-topped signal has high levels of harmonic distortion which creates heat in a loudspeaker and is the major cause of loudspeaker com- ponent failure.

CLS.. The abbreviation for curvilinear line source.

Crossover.. An electrical circuit that divides a full band- width signal into the desired frequency bands for the loudspeaker components.

dB (decibel).. A numerical expression of the relative loud- ness of a sound. The difference in decibels between two sounds is ten times the Base 10 logarithm of the ratio of their power levels.

DC.. Abbreviation for direct current.

Diffraction.. The breaking up of a sound wave caused by some type of mechanical interference such as a cabinet edge, grill frame or other similar object.

Diaphragm.. A thin flexible membrane or cone that vibrates in response to electrical signals to produce sound waves.

Distortion.. Usually referred to in terms of total harmonic distortion (THD) which is the percentage of unwanted har- monics of the drive signal present with the wanted signal. Generally used to mean any unwanted change introduced by the device under question.

Driver.. See transducer.

Dynamic Range.. The range between the quietest and the loudest sounds a device can handle (often quoted in dB).

Efficiency.. The acoustic power delivered for a given elec- trical input. Often expressed as decibels/watt/meter (dB/w/m).

ESL.. The abbreviation for electrostatic loudspeaker.

Headroom.. The difference, in decibels, between the peak and RMS levels in program material.

Hybrid.. A product created by the marriage of two different technologies. Meant here as the combination of a dynam- ic woofer with an electrostatic or ATF transducer.

Hz (Hertz).. Unit of frequency equivalent to the number of cycles per second.

Imaging.. To make a representation or imitation of the original sonic event.

Impedance.. The total opposition offered by an electric circuit to the flow of an alternating current of a single fre- quency. It is a combination of resistance and reactance and is measured in ohms. Remember that a speaker’s imped- ance changes with frequency, it is not a constant value.

Inductance.. The property of an electrical circuit by which a varying current in it produces a varying magnetic field that introduces voltages in the same circuit or in a nearby circuit. It is measured in henrys.