Audio Terminology And Definitions Dictionary
or Phase Alternate Line, is the dominant global format for analog television
broadcasting and video display. It is based on 625-line frames broadcast at 50
fields, or 25 frames per second, based on the 50 Hz AC supply in the countries
that have adapted the system. As with NTSC broadcasts, the signal is interlaced
into two fields of 312 lines each. Note: Brazil uses a variant of PAL (PAL-M)
that uses 525 lines at 60 Hz.
In this case, a "pan" refers to a sound that moves from one speaker to
another. Examples include the sound of a car as it races across the screen from
left to right or a helicopter that suddenly flies into the center of the action
from behind you.
Parallel/Series All electrical components can be connected in series or in parallel. Their effect on signal may reverse depending on the type of connection. An inductor connected in series with a woofer will
provide a simple low pass filter. A capacitor connected in series with a tweeter will provide a high pass filter. An inductor connected in parallel with a series capacitor will help create a 12dB/octave high pass filter for a tweeter. A capacitor connected in parallel with a series inductor will help create a 12dB/octave low pass filter for a woofer. Band pass filters can be created by means of a series
capacitor and series inductor, or by a mixture of series and parallel capacitors and inductors.
Passive A component unconnected electrically to the signal source, such as an Auxiliary Bass Radiator.
Or a component unconnected to a source of mains power, such as a passive pre-amplifier which acts
purely as a source signal switching/routing device providing control functions for a power amplifier.
An equalizer with several user-accessed adjustments (usually amplitude and "Q," or the range of frequencies affected by one
In a loudspeaker, a diaphragm without a "motor" attached to it (hence "passive"). The speaker responds to pressure from inside the enclosure in
such a way as to augment the system's bass response.
PCB Printed Circuit Board.
Code Modulation) Often called "multi-bit." A digital data structure
composed of "words" made up of a (generally even) number of individual bits
(either "0s" or "1s"). PCM completely defines the amplitude or strength
of the sample it represents. Words follow each other at a very high rate, called
the "sampling frequency." For example, the PCM data structure used by the CD
is often referred to as 16/44.1.This means that each word is composed of 16 bits
and that words follow each other at the rate of 44,100 per second (or 44.1 kHz).
The most common PCM data structure for DVDs is 24/96, or 24-bit words at the
rate of 96,000 per second (or 96 kHz).
Peak Output Sudden bursts of power are required in response to certain types of music. Loud drum beats
and percussive piano playing demands a high peak output power from an amplifier. Failure to do so
causes signal compression, resulting in a squashed thick sound as if the drum sticks or piano hammers are made of sponge.
Pentode Commonly used valve type. Contains cathode,
anode, grid and two further electrodes.
The relative timing of two or more signals. Signals reproduced in time with each
other are said to be "in phase" while signals reproduced out of sync with
each other are said to be "out of phase" to one degree or another. Properly "phased" loudspeakers, where each loudspeaker
system in an audio/video system emits a positive pulse when the amplifier
delivers one, are necessary for proper spatial reproduction of music or movie
soundtracks. In addition, phase is central to understanding how a matrix works.
Phonostage The extra equalization and gain stage required to amplify signal from a pickup cartridge to line
level. The RIAA equalization is necessary because bass signals are compressed to allow them to be cut onto vinyl records. There would be insufficient space otherwise. Moving magnet cartridges, which typically deliver output in mV (for 5cm/sec standard acceleration) require less amplification than most moving coil cartridges which deliver output typically in uV for the same acceleration
Pilot Tone The 19 kHz tone carrier tone on which stereo sum and difference signals are broadcast. It is removed by the stereo decoder of FM tuners.
A type of equalized random noise that contains
equal amounts of energy in each of the ten audible octaves. Extensively used in
audio testing, it resembles the energy distribution found in music.
A common informal term for "picture element." A pixel is the single smallest
point on a screen or chip surface that is used to construct a video image.
Pixels are arranged in rows and columns in order to produce a complete image.
Pixel density is the actual number of physical picture elements on a screen
surface or an LCD/DLP projection chip. LCD and plasma screens as well as LCD/DLP
projectors are called "fixed pixel" devices for this reason. The higher the
pixel count, the higher the resolution capability of the video display device.
Pixel density is sometimes referred to as a device's "native resolution."
A pixel count of 1024 x 768 (1,024 pixels across by 768 pixels down, for a total
of 786,432 pixels) is sufficient for DVD. However, 720p HDTV signals need a
display with 921,600 pixels (1260 x 720) to show the signal's full resolution.
A 1080i or 1080p signal for sources such as HDTV broadcasts and Blu-ray discs
needs a native pixel count of 2,073,600 (1920 x 1080) for a one-to-one
representation of the 1080i or 1080p signal.
A generic term for a comparatively large, flat driver that most often is as
large as the height and width of the speaker itself. Planar drivers, when
properly excited by an amplifier's signal, move air equally well from all
points—front and rear—on their surface. (Dynamic drivers, in contrast, are
small, radiate in only one direction, and are the only active elements on a
A plasma TV display is one type of "flat panel" technology. Plasma displays
consist of very small cells, each containing two glass panels separated by a
narrow gap in which neon-xenon gas is injected and sealed in plasma form. The
gas is electrically charged at specific intervals to strike red, green, and blue
phosphors in order to create an image. Each red, green, and blue phosphor
element is called a sub-pixel. Combined, they form a pixel.
Polarity The difference between positive and negative.
Capacitors These very high-quality
components are usually employed in the signal path where large-value capacitors
are not required. Their advantage is that they have a very small "Miller
Effect," or memory, compared to electrolytic capacitors. This means that each
subsequent signal passing through them has greatly reduced coloration, resulting
in better fidelity.
opening in a speaker enclosure that allows the back wave from a woofer to exit
the cabinet and reinforce the woofer's front wave.
(See also: bass reflex
Potentiometer The device used to provide volume level setting. Ideally a potentiometer is a variable resistor. Often shortened colloquially to 'pot'.
An electronic circuit or component that
increases the level of signal from a source or preamplifier until it is able to
drive a loudspeaker.
Power Handling A
loudspeaker's ability to dissipate heat so that input from an amplifier does
not damage the voice coils. Though typically specified in watts, there is no
industry-wide standard for this specification.
Power Output The amount of power, usually measured in watts per channel, delivered by a power amplifier
or integrated amplifier to loudspeakers. The rated maximum rms or continuous sine wave power output
is a less relevant indicator of the dynamic range capability of an amplifier than its peak output power
capability or its peak current delivery measured in Amps. Amplifier power output is usually specified
relative to an 8 Ohm resistive load. However the majority of loudspeakers present a load that varies
according to audio frequency, rising at loudspeaker drive unit resonant frequency but often decreasing elsewhere across the bandwidth. Impedances lower than 4 Ohms require an amplifier to have considerable current drive capacity.
A little understood but nonetheless important specification that defines the
total radiated acoustic output of a loudspeaker. Power response is measured at
several angles in the far (random-phase, or reverberant) field. It is a better
indication of "real world" loudspeaker performance than more-common anechoic
Power Supply Electronic components deriving their power from a mains source require a transformer, smoothing capacitors and rectifier to turn the mains AC into a stable DC rail voltage. Amplifiers in particular
are heavily dependent on a stable rail voltage. However components as varied as CD players, DACs and turntables also benefit from well configured power supplies often as separate items. Power supplies can be a useful retrofit upgrade.
An audio/video system's switching center, a preamplifier allows the user to
choose a particular source component (CD or tuner, for example) and to adjust
tonal quality and system volume.
Presence Band The middle range of audio frequencies to which the ear is most sensitive. Typically taken to mean
the 1-4kHz frequency range.
A phenomenon of human hearing that describes how we judge the origin of a sound
coming from more than one direction by the location from which we first hear
that sound. For example, if a car on your left honks its horn, the sound reaches
your left ear before it reaches your right ear. Using this information, your
brain concludes that the car is on your left. (Also known as the Haas Effect.)
Printed Circuit Board (Abbr: pcb). The board onto which a conducting track and solid state components - resistors,
capacitors and the like - are mounted. pcbs may be single sided or double sided, fitted vertically or
Progressive scan devices show an image by scanning in sequential order each line
(or row of pixels) that make up a frame. In other words, in progressive scan,
the image lines (or pixel rows) are scanned in numerical order (1,2,3) down the
screen from top to bottom, instead of in an alternate order (lines or rows
1,3,5, etc., followed by lines or rows 2,4,6) as in interlaced scanning.
Progressive scanning presents a smooth, detailed image that is virtually immune
to a phenomenon called "interlace flicker."
The overlapping branches of acoustics and psychology where research is conducted into
human perception of sound.
Pulse Width Modulation. A form of digital recording which makes use of the width of a digital pulse.