Glossary of Audio Terms

The front panel of a loudspeaker enclosure - typically the panel to which the woofers and horns are mounted.

The preferred method for hum-minimizing interconnection of sound system components using a shielded coaxial cable with a twisted-pair of center conductors. A differential output stage simultaneously drives the two center lines, one with positive polarity and the other negative, with the shield connected to ground. The voltage difference between these two wires is the audio signal. Since the balanced input stage amplifies only the difference between the lines, it rejects everything else (electrically induced noise) that is common to the lines. Usually terminated with 1/4" TRS or XLR connectors. In a classic balanced audio circuit, the two legs of the circuit (+ and -) are isolated from the circuit ground by exactly the same impedance. Each leg carries the signal at exactly the same level but with opposite polarity with respect to ground. In some balanced circuits, only one leg actually carries the signal but both legs exhibit the same impedance characteristics with respect to ground. Good balanced input circuits offer excellent rejection of common-mode noise (a noise signal carried in equal amplitude on both conductors, but with the same polarity with respect to ground, instead of opposite) induced into the line and also make proper (free of ground loops) system grounding easier.

The connector into which a banana plug can be inserted.
See: Banana Plug

A single conductor electrical connector with a banana-shaped spring-metal tip most often used on audio power amplifiers for the loudspeaker wiring.

The range of frequencies that will pass through a device with a loss of less than 3 dB (or some other explicitly stated amount), expressed in Hertz, with an upper and lower limit.

A type of input or output signal connector that uses screw terminals for attaching wires. Barrier strips are common in permanent installations where quick disconnects are unnecessary because they save the cost and labor of using XLR or 1/4" connectors.

A measure of sound "warmth"

A loudspeaker enclosure design in which an otherwise sealed enclosure employs a port or duct the volume of which is chosen to provide additional low-frequency acoustical output.

The use of an active crossover to split the signal spectrum before the amplification stage. Bi-amplification specifically refers to using two frequency bands high and low -so that each band can be amplified separately. More sophisticated techniques involve three-, four-, and sometimes even five-way splitting.

A high frequency signal that is introduced during the magnetic recording process to overcome the non-linearity of the system. In a transistor amplifier circuit, the amount of quiescent current or voltage applied to set the circuit midpoint and/or to improve its linearity.

Output transistors in power amplifiers are generally either MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) or bipolar. Bipolar transistors of all sorts of power-handling capability come in either NPN or PNP types, which is useful for true complementary circuit configurations because one type will handle the positive voltage swings and the other will handle the negatives. Another difference with bipolar devices is the way they are driven in a circuit. While a field-effect transistor varies its conductance in response to a voltage at its gate, a bipolar transistor conducts a large current in response to a smaller current flowing in (NPN) or out (PNP) of its base.

A miniature bayonet locking connector for coaxial cable.

A type of microphone that detects the changes of the sound pressure levels at the boundaries within an acoustic space in order to reduce interference between direct and reflected sound.

A term used to describe an unwanted side effect of using compressors incorrectly, whereby the background noise of the source rises and falls depending on the behavior of the main program.

An amplifier configuration in which two channels of an amplifier are connected together-but in opposite polarity-to function as a monaural unit providing double the power of a single channel, at twice the load impedance. The speaker load usually connects across the two positive output terminals of the amplifier.