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40 Glossary of Audio Terms
AC. Abbreviation for alternating current.
Active crossover. Uses active devices (transistors, IC’s, tubes) and
some form of power supply to operate.
Amplitude. The extreme range of a signal. Usually measured
from the average to the extreme.
Arc. The visible sparks generated by an electrical discharge.
Bass. The lowest frequencies of sound.
Bi-Amplification. Uses an electronic crossover, or line-level pas-
sive 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 material 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 amplifier 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 component failure.
CLS. The abbreviation for curvilinear linesource.
Crossover. An electrical circuit that divides a full bandwidth
signal into the desired frequency bands for the loudspeaker
components.
dB (decibel). A numerical expression of the relative loudness 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 distor-
tion (THD) which is the percentage of unwanted harmonics 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 electrical
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 tech-
nologies. Meant here as the combination of a dynamic woofer
with an electrostatic 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 frequency. It is
a combination of resistance and reactance and is measured in
ohms. Remember that a speaker’s impedance changes with fre-
quency, 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 intro-
duces voltages in the same circuit or in a nearby circuit. It is
measured in henrys.
Inductor. A device designed primarily to introduce inductance
into an electrical circuit. Sometimes called a choke or coil.
Linearity. The extent to which any signal handling process is
accomplished without amplitude distortion.
Midrange. The middle frequencies where the ear is the most sen-
sitive.
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