B - Symbol for susceptance and, confusingly, also the symbol for magnetic flux density.
B+ - The symbol for the high voltage power supply found in battery-operated radios featuring vacuum tubes. In these designs there was an "A" supply for the filaments, a "B" supply for high voltage, a "C" supply for bias and a "D" supply for screen grids. [Pittman]
B-3 - Famous organ developed by Laurens Hammond in 1954 and when combined with a Leslie® rotating speaker became a jazz, R&B, and rock 'n' roll staple.
babbling tributary - In LAN technology, a workstation that constantly sends meaningless messages.
back-EMF (back-electromotive force) - Literally, back-voltage, is a phenomena found in all moving-coil electromagnetic systems, but for audio is most often used with respect to loudspeaker operation. This term describes the action where, after the signal stops, the speaker cone continues moving, causing the voice coil to move through the magnetic field (now acting like a microphone), creating a new voltage that tries to drive the cable back to the power amplifier's output. The only way to stop back-emf is to make the loudspeaker "see" a dead short, i.e., zero ohms looking backward, or as close to it as possible.
background music Abbr. BGM - Officially music without lyrics and not performed by the original artist, used as an alternative to silence.
backward masking - Masking of an earlier sound by a later sound arriving. i.e., the second arriving event covers up the first arriving signal. This is only possible because the ear requires time to form an echoic image before it is processed by the central nervous system. If a later sound is much louder it can take precedence over an earlier arriving one (within about 100 to 200 ms).
baffle - In its simplest form, the main speaker mounting board in a cabinet, whose primary purpose is to separate the front and rear sound waves, from here it becomes a very complex subject.
bagpipe - A musical instrument having a flexible bag inflated either by a tube with valves or by bellows, a double-reed melody pipe, and from one to four drone pipes. [AHD]
Baker clamp - A circuit technique dating from the early '50s using a diode as a clamp to prevent deep transistor saturation by providing a path for excessive base drive current. Recently used by National Semiconductor in a popular audio power amplifier IC to aid in fast recovery from peak overloads.
baking - The name for the process required for old analog tapes where they must be put into an oven and "baked" to remove moisture and prevent the oxide from shedding onto the tape heads.
balance control - A control found most commonly on professional and consumer stereo preamplifiers, used to change the relative loudness (power) between the left and right channels. Attenuating the opposite channel makes one channel (apparently) louder. This is most often done (in analog designs) with a dual potentiometer with an "M-N taper." An M-N taper consists of a "shorted" output for the first 50% of travel and then a linear taper for the last 50% of travel, operating oppositely for each channel. Therefore, with the control in its center detent position, there is no attenuation of either channel. Rotating it away from the center position causes one channel to be attenuated, while having no effect on the other channel, and vice-versa.
balanced line - The IEC standard on amplifiers explains a balanced interface by saying that "The purpose of a balanced interface is to transfer a desired signal as a differential voltage on two signal lines." (IEC 60268-3:2001, page 111). It goes on to explain "... only the common-mode impedance balance of the driver, line, and receiver play a role in noise or interference rejection. This noise or interference rejection property is independent of the presence of a desired differential signal. Therefore, it can make no difference whether the desired signal exists entirely on one line, as a greater voltage on one line than the other, or as equal voltage on both of them."
Balanced lines are the preferred method (for hum free) interconnecting of sound systems using a shielded twisted-pair. Because of its superior noise immunity, balanced lines also find use in interconnecting data signals, e.g., RS-422, and digital audio, e.g., AES/EBU. The principal behind balanced lines is that the signal is transmitted over one wire and received back on another wire. The shield does not carry any information, thus it is free to function as a true shield, but must be earth grounded at each end to be successful. This circuit's shining virtue is its great common-mode noise rejection ability. The concept here relies on induced noise showing up equally (or common) on each wire. It is mainly due to EMI (electromagnetic interference: passing through or near magnetic fields), RFI (radio frequency interference: strong broadcast signals), noisy ground references, or a combination of all three. A true balanced line exhibits exactly equal impedance from each line relative to ground, guaranteeing equal noise susceptibility. Since the balanced input stage amplifies only the difference between the lines, it rejects everything else (noise) that is common to the lines. Ball, Roland Sherwood "Ernie" - (b. 1930-2004) American musician/entrepreneur who developed guitar strings and accessories into an art form.
ballistics or meter ballistics - Term describing the response characteristics of a meter indicator. Applies to all meters from original iron vane, taut-band or pivot & jewel mechanical analog designs to LED, LCD or plasma ladder arrays. Two universal standards exist for audio use: the VU meter and the PPM (peak program meter). The indicator attack (or rise) times are specified as well as the decay (or fall) rates along with the recommended detector method.
balun (balanced-unbalanced) - A jargon term originally popularized by radio engineers referring to the balanced to unbalanced transformer used to interface with the radio antenna. Today, expanded to refer to any interface (usually a transformer) between balanced and unbalanced lines or circuitry; may also provide impedance transformation, as 300 ohm balanced to 75 ohm unbalanced, or vice versa. Another popular use is in transitioning between balanced twisted-pair and an unbalanced coaxial cable.
banana jack or 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. Usually configured as a color-coded molded pair (red = hot & black = return) on 3/4" spacing. Also used for test leads and as terminals for plug-in components. The British still refer to these as a GR plug, after General Radio Corporation, the inventor (according to The Audio Dictionary by Glenn D. White).
band-limiting filters A low-pass and a high-pass filter in series, acting together to restrict (limit) the overall bandwidth of a system.
bandoneon - A small accordion especially popular in Latin America. [AHD]
bandpass filter - A filter that has a finite passband, neither of the cutoff frequencies being zero or infinite. The bandpass frequencies are normally associated with frequencies that define the half power points, i.e. the -3 dB points.
bandwidth Abbr. BW - (1) In reference to electronic filters, the numerical difference between the upper and lower -3 dB points of a band of audio frequencies. Used to figure the Q, or quality factor, for a filter. (2) In reference to telecommunications, the size of the communications channel. In analog communications, bandwidth is measured in Hertz (Hz), while digital communications measures bandwidth (data transfer rate) in bits per second.
banhu - Chinese bowed 2-string fiddle.
bantam jacks or TT (tiny telephone) - Shorter and thinner than 1/4" TRS jacks, it is the term for the small patch cables originally used in telephone patchbays.
bar - A unit of pressure equal to one million dynes per square centimeter.
barberpole tone (or effect) - A circuit that produces a continuously ascending or descending tone.
barber's music - Used to describe non-professional music named after the fact that barber's shops used to have a guitar or other acoustic instrument on hand for customer's use while waiting. [Kacirk]
Baroque - Of, relating to, or characteristic of a style of composition that flourished in Europe from about 1600 to 1750, marked by chromaticism, strict forms, and elaborate ornamentation. [AHD]
Barr, Keith Elliot - (b. 1949-2010) American engineer who cofounder MXR and then Alesis Electronics.
barrelhouse - Style of boogie piano playing. [Decharne]
barrier strips or terminal strips - a type of wiring connector provided with screwdown posts separated by insulating barrier strips. Used for balanced and unbalanced wiring connections, where each wire is usually terminated with a crimped-on spade- or ring-connector and screwed in place.
Barron, Louis & Bebe - (Louis: b. 1920-1989; Bebe: b. 1925-2008) American husband and wife team that composed the first electronic-music score featured in the movie, Forbidden Planet, in 1956.
baseband - A transmission medium with capacity for one channel only. Typically found in local area networks (LANs). In baseband LANs, the entire bandwidth, or capacity, of the cable is used to transmit a single digital signal. Everything on that cable (transmitted or received) must use that one channel, which is very fast, so each device needs only to use that high speed channel for only a little amount of time. Therefore all attached devices (printers, computers, databases) share by taking turns using the same cable. Baseband as used in videoconferencing means audio and video signals are transmitted over separate cables.
baseband signaling - Transmission of a digital or analog signal at its original frequencies; i.e., a signal in its original form, not changed by modulation.
BASH® (Bridged Amplifier Switching Hybrid) - The registered trademark of Indigo, an OEM company, for their patented (U.S. 5,075,634 & U.S. 5,510,753) Class H power amplifier technology that uses a fast-response, pulse-width modulated power supply and a linear Class AB amplifier. BASH modules are found in many powered loudspeakers from Cambridge Audio to Tannoy.
bass management - A circuit that sums all the frequencies below 80Hz from the main channels and the signal from the LFE channel and delivers it (normally) to the subwoofer.
bass ratio (BR) - An objective measure of sound "warmth."
bass reflex - Invented by Thuras in 1930, a type of cabinet design featuring a "port" (a vent or opening of any shape) on the baffle to allow the rear sound wave to exit (in phase -- that is the trick) with the front wave. Originally a trademark of the Jensen Company in the 1930s. [White], this popular design is also called a vented loudspeaker.
bathythermograph - A device used in underwater acoustics to measure water temperature at different depths for the purpose of determining the velocity of sound in seawater.
battery - Invented and named by Benjamin Franklin in the 1748. He named his device for storing electrical charge for their resemblance to rows of guns.
battle axe - Musician slang for a trumpet. [Decharne]
baud rate - (pronounced "bawd"; after Baudot Code named for the French telegrapher Emile Baudot, b. 1845-1903) The transmitted signaling speed, or keying rate of a modem.
Bauer, Benjamin - (b. 1913-1979) Russian-American engineer who made powerful contributions to the development of many electroacoustic devices including microphones (see: Unidyne), phonograph pickups and tape recording heads. He worked for Shure from 1936 (as a co-op student) to 1957 (leaving as vice president), then CBS Laboratories as vice president.
Baxandall tone controls - The most common form of active bass and treble tone control circuit based upon British engineer P.J. Baxandall's paper "Negative Feedback Tone Control -- Independent Variation of Bass and Treble Without Switches," Wireless World, vol. 58, no. 10, October 1952, p. 402. The Baxandall design is distinguished by having very low harmonic distortion due to the use of negative feedback.
bazouki or bouzouki - A Greek stringed instrument having a long fretted neck and usually pear-shaped body. [AHD]
BCC (binaural cue coding) - An audio coding technology.
BCD - (1) (binary-coded decimal) Pertains to a number system where each decimal digit is separately represented by a 4-bit binary code; for example, the decimal number 23 is represented as 0010 0011 (2 = 0010 and 3 = 0011, grouped together as shown), while in straight binary notation, 23 is represented as 10111. (2) (binary-coded digit) A digit of any number system that is represented as a fixed number of binary digits; from the previous example, the decimal digit 23 is represented as 10111.
beamforming - Popular buzz word in audio pick-ups for teleconferencing. Makes use of spatial filters and arrays.
beam steering - Common name for the technology that allows changing the directionality of a loudspeaker array by using separate DSP and power amplifiers for each driver in the array. This allows each driver to be delayed and equalized separately as necessary to manipulate the vertical coverage pattern. The whole beam can be moved upward, downward, and made broader or narrower as desired.
beat - To cause a reference wave to combine with a second wave so that the frequency of the second wave can be studied through time variations in the amplitude of the combination. [AHD]
beatboxing - Using the mouth, throat and nasal cavity as a vocal percussion instrument to create hip hop drum sounds similar to record scratching.
beat frequency - Equal to the absolute value of the difference in frequency of two waves beating together (see "beat" above).
beat matching or beat mixing - Used by disc jockeys to match beats to produce a seamless segue, or transition, between songs, or by turntablists between segments of different songs being mixed together.
Beauchamp, George - (b. 1899-1941) American inventor and entrepreneur who is credited with inventing the first electric guitar, named the "Frying Pan" in 1931 and cofounding Rickenbacker Guitars.
bebop - Modern jazz style developed by Charlie Parker, Dizzy Gillespie and others in the early 1940s. Dizzy put out a single called "Bebop" in 1945 and also released "He Beeped When He Shoulda Bopped," in 1946. [Decharne]
Begun, Semi Joseph - (b. 1905-1995) Born in German, he immigrated to the U.S. in 1935 and pioneered magnetic tape recording. He wrote the first book published on magnetic recording and invented many recording products including the first consumer tape recorder as well as developing the technology that gave birth to the Black Box flight data recorder.
bel Abbr. b, B - Ten decibels. [After Alexander Graham Bell.] The Bel was the amount a signal dropped in level over a one-mile distance of telephone wire.
Bell, Alexander Graham - (b. 1847-1922) Scottish-born American inventor of the telephone. The first demonstration of electrical transmission of speech by his apparatus took place in 1876. Bell also invented the audiometer, an early hearing aid, and improved the phonograph. [AHD]
belly fiddle - Guitar. [Decharne]
BEM (boundary element modeling) - A mathematical modeling method using only a mesh of the surface of a wave, making computations easier and faster.
benders or bending or circuit-bending - The popular art of altering low-cost electronic devices to make them produce new and unique sounds such as squawks, beeps and bongs, thus creating a homemade musical instrument. Reed Ghazala is credited with inventing this new music genre.
bending wave physics (also known as Distributed Mode Loudspeakers or DML) - Flat panel loudspeaker innovations based on the bending wave principal. Its simplest form consists of a small driver and a large thin panel. The driver coil excites the panel but due to the large flat surface, it does not move in and out but rather "bends"- that is, deforms in a bending wave. This wave travels throughout the panel provoking 360-degree radiation of sound in the process -- very different from the way a conventional loudspeaker cone produces sound by "pushing" air. Careful and complex design of the rigidity of the thin flexible panel allows it to increase from the middle to the edges at an equal ratio. This allows one panel to control most of the audio range, thus eliminating multiple drivers and crossover networks.
BeOS (Be operating system) - An operating system (OS) developed by Be Incorporated in 1996, called the first true "media OS."
BER (bit error ratio) (also called bit error rate) – (1) The ratio of the number of erroneous bits divided by the total number of bits transmitted, received, or processed over some stipulated period. (2) The number of bits processed before an erroneous bit is found (e.g., 10E13), or the frequency of erroneous bits (e.g., 10E-13).
Berliner, Emil - (b. 1851-1929) German-born American inventor who made important contributions to telephone technology and developed the phonograph record disc.
Bessel crossover - A type of crossover utilizing low-pass filter design characterized by having a linear phase response (or maximally flat phase response), but also a monotonically decreasing passband amplitude response (which means it starts rolling off at DC and continues throughout the passband). Linear phase response (e.g., a linear plot of phase shift vs. frequency produces a straight line) results in constant time-delay (all frequencies within the passband are delayed the same amount). Consequently the value of linear phase is it reproduces a near-perfect step response, i.e., there is no overshoot or ringing resulting from a sudden transition between signal levels.
B-field or magnetic flux density - The amount of magnetic flux through a unit area taken perpendicular to the direction of the magnetic flux.
B-format or soundfield microphone - A specialized microphone array comprised of four cardiod or supercardiod microphones: three to measure left-right, front-back, up-down sound pressure levels and another that measures overall sound pressure level. This arrangement is known as the A-Format, while another one, the B-format, is created by signal processing. This forms the heart of an Ambisonics and other such systems.
BGA (ball grid array) - A type of miniature package for integrated circuits containing hundreds of pins.
BGM or background music - Officially music without lyrics and not performed by the original artist, used as an alternative to silence.
biamp, biamplified, or biamplification - Term used to refer to a 2-way active crossover where the audio signal is split into two paths, and using separate power amplifier channels for each driver.
bias or biasing - Preset voltages or currents in an electronic circuit that determine the electrical operating points of certain devices.
BICSI® (Building Industry Consulting Services, International) - A telecommunications association that is a worldwide resource for technical publications, training, conferences, and registration programs for low-voltage cabling distribution design and installation.
bidirectional microphone or figure-of-eight - A microphone with a polar response which is equal with respect to the front and rear and not at all to the sides.
bipolar transistor - Pertaining to a semiconductor technology in which transistors are built from alternating layers of positively and negatively doped semiconductors material. [IEEE]
BIEM (Bureau International des Sociétés Gérant les Droits d'Enregistrement et de Reproduction Mécanique) - An international organization representing mechanical rights societies found in most countries. They license the reproduction of songs (including musical, literary and dramatic works). Their members are composers, authors and publishers and their clients are record companies and other users of recorded music. They also license the downloading of music via the Internet.
bifilar windings - A term most often associated (in the pro audio industry) with audio transformer design describing the winding technique of laying two wires side-by-side, providing essentially unity coupling, thus reducing leakage inductance to negligible amounts. Literally two threads from Latin bi- two, and filum thread.
bigit - Very early contraction term for "binary digit," now obsolete. (Mentioned by Edmund C. Berkeley in his book The Computer Revolution, Doubleday, 1962, page 234.)
bilinear transform - A mathematical method used in the transformation of a continuous time (analog) function into an equivalent discrete time (digital) function. Fundamentally important for the design of digital filters. A bilinear transform ensures that a stable analog filter results in a stable digital filter, and it exactly preserves the frequency-domain characteristics, albeit with frequency compression.
BIM (building information modeling) - A term coined by Georgia Institute of Technology for a very complex method of using digital models for design and construction of buildings.
bimorph - A cantilever device having two active piezoelectric layers where an electrical field causes one layer to bend out and the other layer to bend in.
binary - A condition in which there are two possible states; for example, the binary number system (base-2) using the digits 0 and 1.
binary logarithm - A logarithm based on the powers of 2 (aka base 2).
binaural cue coding or BCC - An audio coding technology.
binaural recording or binaural sound Recording made using two microphones placed in the ear canals of an anatomically accurate dummy head, such that all the normal spatial attributes of the human head are present (just as in real listening situations) when the recording is made. Designed to be played back through headphones, the results are nothing but astonishing. First time listeners to binaural recordings often swear someone is there with them, talking and walking around them, such is the realism accomplished. binding post - Alternate name for banana jacks above, derived from the capability to loosen (unscrew) the body and insert a wire through a hole provided in the electrical terminal and tighten the plastic housing down over the wire insulation, holding the wire in place.
birefringence or double refraction - The resolution or splitting of a light wave into two unequally reflected or transmitted waves by an optically anisotropic medium such as calcite or quartz.
bit Abbr. b - Abbreviation for binary unit or binary digit. The smallest amount of digital information. A bit can store or represent only two states, 0 and 1. [The original term binary unit was coined by John Tukey of Bell Laboratories to represent the basic unit of information as defined by Shannon as a message representing one of two states.]
bit clock - The synchronizing signal that indicates the rate of individual data bits over a digital audio interface.
bit error rate or bit error ratio or BER – (1) The ratio of the number of erroneous bits divided by the total number of bits transmitted, received, or processed over some stipulated period. (2) The number of bits processed before an erroneous bit is found (e.g., 10E13), or the frequency of erroneous bits (e.g., 10E-13).
bit rate - The rate or frequency at which bits appear in a bit stream. Applied to digital audio, bit rate (kbits/sec/channel) equals the sampling rate (kHz) times the number of bits per sample. The data bit rate for a CD, for example, is 1.41M bits per second (44.1 kHz x 16 bits per sample x 2 channels). [The oft-quoted CD bit rate of 4.3218 MHz is for the raw bit rate which comes from multiplying 7,350 frames per second by 588, the number of channel bits.]
bits (data converter) - The number of bits determines the data converter precision. The more bits available, the more precise the conversion, i.e., the closer the digital answer will be to the analog original. When an analog signal is sampled (at the sampling frequency), it is being sliced up into vertical pieces. Each vertical piece is then estimated as to its amplitude. This estimation process is the data converters job. It compares the original signal against its best estimate and chooses the closest answer. The more bits, the more choices the data converter has to choose from. The number of choices is the number "2" raised to the number of bits (this explanation is simplified for clarity). For example, 16-bits creates 2 to the 16th power of choices, or 65,536 possible answers for the converter to choose from. And the higher the sampling rate, the more slices for any given time period. Again, the more slices, the more accurate will be the data conversion. All of which, ultimately determines how well the reproduced signal sounds compared to the original. For example, if a signal is recorded using "16-bits at 48 kHz", then for every one second of the audio signal, it is sliced up into 48,000 pieces. Then each piece is compared against a ruler with 2 to the 16th graduations, or 65,536 voltage levels. Each sample instant is compared against this ruler and one value is assigned to represent its amplitude. For each second, 48,000 samples are given specific values to represent the original signal. If the same signal is recorded using "24-bits at 96 kHz" then for the same one second period, there will be 96,000 slices, or samples, and each one will be compared against a voltage ruler now divided into 2 to the 24th divisions, or 16,777,216 choices.
bit stream - A binary signal without regard to grouping.
bit-mapped display - A display in which each pixel's color and intensity data are stored in a separate memory location.
Black, Harold S. - (b. 1898-1983) American electrical engineer and innovator most noted for his invention of negative feedback (U.S. patent 2,102,671).
black hole music - Name given by astronomers to detecting the deepest note ever generated in the cosmos, a B-flat 57 octaves below middle C.
Blackmer, David - (b. 1927-2002). American scientist, inventor and businessman best known for founding dbx, Inc. and pioneering audio-grade VCAs for signal processing.
black noise - Silence (zero power density with a few random spikes allowed).
black stick - Clarinet. [Decharne]
blame shifter - Shifts the pitch of mistakes down one octave so the audience thinks it was the bass player.
blue note - A flatted note, especially the third or seventh note of a scale, in place of an expected major interval. [AHD]
Bluetooth - The code name given a wireless network protocol, after a 10th century Danish king, Harald Bluetooth, who unified Denmark. The code name was adopted in April, 1998, when Intel and Microsoft formed a consortium between themselves IBM, Toshiba, Nokia, Ericsson and Puma Technology. This protocol promised to bring wireless Internet to the masses, making the Web as ubiquitous as radio and TV. The Bluetooth SIG (special interest group), now numbering over 2000 companies, sees a world where equipment from different manufacturers works seamlessly together using Bluetooth as a sort of virtual cable.
Blumlein, Alan Dower - (b. 1903-1942) English engineer who in a short working life span of 15 years wrote or co-wrote 128 patents, developed stereophonic sound, designed new uses for microphones, designed a lateral disc-cutting system making modern records possible, developed much of the 405-line high definition television system broadcast in Britain until 1986, and improved radar systems such that they still operated 40 years later.
Blu-ray Disc - A trademark of Sony for their optical disc video recording format developed for recording, rewriting and playback of HDTV, and is predicted to find its way into audio recording use.
BNC (bayonet Neill-Concelman) - A miniature bayonet locking connector for coaxial cable. It was developed in the late '40s by a collaboration of Paul Neill and Carl Concelman based on a patent granted to the late Dr. Octavio M. Salati.
Bode, Hendrick Wade - (b. 1905-1982) American engineer who pioneered modern Control theory and Electronic Telecommunications.
Bode plot or Bode diagram - A method developed by Hendrick Wade Bode to represent the gain and phase of a system as a function of frequency. Usually seen as a plot of log-gain and phase-angle values on a log-frequency scale.
bodhran - A hand-held goatskin drum used in traditional Irish music and often played with a stick. [AHD]
Bo Diddley - (b. 1928-2008) Stage name for the American rock legend. Born Otha Ellas Bates, his name was changed to Ellas B. McDaniel by his mother's first cousin, Gussie McDaniel, who raised him. In 1954, band member Billy Boy Arnold, a leading American blues harmonica player, came up with Bo Diddley as a stage name for McDaniel. He described it as a "bowlegged guy, a comical looking guy." Although another possibility is that there is a one-string guitar -- native to the Mississippi Delta where McDaniel was born, called a Diddley Bow, but it is said that Bo Diddley had never played one.
Bogen, David - (b. 1889-1974) American Russian immigrant who helped pioneer the hi-fi audio industry.
bonded magnet motors - Generic name for a new class of ironless electric motors that do not use iron or ferrite permanent magnets in their construction. Instead they use anisotropic NdFeB (neodymium-iron-boran) bonded magnets (aka neodymium magnets). Of interest to pro audio users since experimental loudspeakers based on bonded magnets are being researched as not only lighter and more eco-friendly but produce audio with lower distortion.
Boner, C.P. (b. 1900-1979) American physicist specializing in acoustics, considered the father of room equalization (U.S. patent 3,457,370).
bongo - One of a pair of connected tuned drums that are played by beating with the hands. [AHD]
boogaloo - Nickname given to Abie "Boogaloo" Ames (b. 1921-2002) in the 1940s for his boogie-woogie piano style.
boogie - (1) Strongly rhythmic rock music. [AHD]
boogie-woogie - A style of blues piano playing characterized by an up-tempo rhythm, a repeated melodic pattern in the bass, and a series of improvised variations in the treble. [AHD]
Boole, George - (b. 1815-1864) British mathematician who devised a new form of algebra that represented logical expressions in a mathematical form now known as Boolean Algebra.
Boolean Algebra - An algebra in which elements have one of two values and the algebraic operations defined on the set are logical OR, a type of addition, and logical AND, a type of multiplication. [AHD]
boost converter - A type of step-up voltage converter, used in DC-DC conversion, favored by designers for its low cost and simplicity.
boost/cut equalizer - The most common graphic equalizer. Available with 10 to 31 bands, on 1-octave to 1/3-octave spacing. The flat (0 dB) position locates all sliders at the center of the front panel. Comprised of bandpass filters, all controls start at their center 0 dB position and boost (amplify or make larger) signals by raising the sliders, or cut (attenuate or make smaller) the signal by lowering the sliders on a band-by-band basis. Commonly provide a center-detent feature identifying the 0 dB position.
bop - A post-World War II style of jazz characterized by rhythmic and harmonic complexity, improvised solo performances, and a brilliant style of execution. [AHD] The word "bebop" was shortened to "bob" with Charlie Parker's 1947 recording "Bongo Bop." [Decharne]
Boucherot, Paul - (b. 1869-1943) French engineer who studied the phenomena of electric conduction, introducing the concept of reactive power and inventing the synchronous electric motor in 1898. He also studied the thermal energy of the seas. The Claude-Boucherot Process described a scheme to power a turbo-alternator using warm seawater from tropical oceans to produce steam in a vacuum chamber. Theorem of Boucherot: In an AC electrical network, the total active power is the sum of the individual active powers, the total reactive power is the sum of the individual reactive powers, but the total apparent power is NOT equal to the sum of the individual apparent powers.
Boucherot cell or Zobel network – (1) A filter designed according to image parameter techniques. (2) In reference to amplifiers, networks are used in audio amplifiers to dampen out high frequency oscillations that might occur in the absence of loads at high frequencies. It is the commonly seen series resistor-capacitor combination located directly at the output of the driver stage, just before the output inductor (in analog power amplifiers). Typical values are 5-10 ohms in series with 0.1 microfarads. The network limits the rising impedance of a loudspeaker due to the speaker coil inductance. The output inductor found in most analog power amplifiers used to disconnect the load at high frequencies further aggravates this phenomenon.(3) In reference to loudspeakers, crossover designs include zobel networks wired across the tweeter (high frequency) driver to compensate for the rise in impedance at high frequencies due to the inductance of the voice coil. The goal here is to try to keep the load seen by the crossover circuitry as resistive as possible. [After Dr. Zobel's paper appearing in the Bell Labs Journal: Zobel, O. J., "Theory and Design of Uniform and Composite Electric Wave Filters," Bell Sys. Tech. J., Vol. 2, pp. 1-46, Jan 1923.]
boundary microphone - A PZM (pressure zone microphone) is an example of a boundary microphone. Utilizes a technique and design where the microphone is mounted on a flat plate which acts as a reflective surface directing sound into the mic capsule. The PZM principle uses the compression and decompression of air between the plate and the membrane in parallel with the plate (the gap is very narrow, typically only a millimeter or less. This arrangement gives about 6 dB extra amplification of the signal, which means 6 dB less inherent electronic noise.
bouzouki (also bazouki) - A Greek stringed instrument having a long fretted neck and usually pear-shaped body. [AHD]
Bowditch curve or Lissajous figure - A special case of X-Y plot in which the signals applied to both axes are sinusoidal functions. For a stable display the signals must be harmonics. Lissajous figures are useful for determining phase and harmonic relationships. (After J. A. Lissajous) [IEEE]
Bozak, Rudy - Credited with designing and manufacturing the first DJ mixer, the Bozak CMA 10-2DL.
BPL (broadband over power lines) - General term for any of the "carrier-current" systems that conduct signals over existing electrical wiring or power lines.
BPM (beats per minute) - A measure of music tempo.
BPM - European expo focusing on DJing, club culture & electronic music.
Bps (always uppercase B) - Abbreviation for bytes per second.
bps (always lowercase b) - Abbreviation for bits per second.
Braille, Louis (b. 1809-1852) French musician, educator, and inventor of a writing and printing system for blind or visually impaired people (1829). He lost his sight at the age of three. [AHD] His braille system was first developed for blind musicians.
breathing - The audible effect caused by varying noise (or hiss) levels down around the noise floor usually caused by turning on and off gates and expanders. [Izhaki] Technically it is a modulation of the noise floor.
breve - A note equivalent to two whole notes. [AHD]
brickwall filter - A low-pass, high-pass or bandpass filter exhibiting extremely steep rolloff rates of greater than 50 dB/octave such that the response resembles a "brick wall."
bridge - (1) In communications networks a bridge is a device that connects two or more different networks and forwards packets between them; specifically a device that (a) links or routes signals from one ring or bus to another, or from one network to another, (b) may extend the distance and capacity of a single LAN system, (c) performs no modification to packets or messages, (d) operates at the data-link layer of the OSI--Reference Model (Layer 2), (e) reads packets, and (f) passes only those with addresses on the same segment of the network as the originating user. (2) A functional unit that interconnects two local area networks that use the same logical link control (LLC) procedure, but may use different medium access control (MAC) procedures. (3) A balanced electrical network, e.g., a Wheatstone bridge.
bridged amplifier or BTL (bridge-tied load) – In reference to amplifiers, an amplifier configuration where the loudspeaker load is connected between the two hot outputs of two amplifiers operating in bridged amplifier mode, i.e., anti-phase, where the output of one amplifier drives the the second amplifier out of phase, or inverted, and operates at unity gain. Thus the second amplifier (usually the second channel of a two channel design) acts as a current amplifier (with inverting voltage). This doubles the output voltage (one-half from the first amplifier and one-half from the second amplifier) and theoretically produces four times the power output (double the voltage equals double the current equals four times the power).
bridge rectifier - The arrangement of four diodes to achieve full-wave rectification; used to convert AC voltage to DC voltage.
bridge-tied load - In reference to amplifiers, an amplifier configuration where the loudspeaker load is connected between the two hot outputs of two amplifiers operating in bridged amplifier mode, i.e., anti-phase, where the output of one amplifier drives the the second amplifier out of phase, or inverted, and operates at unity gain. Thus the second amplifier (usually the second channel of a two channel design) acts as a current amplifier (with inverting voltage). This doubles the output voltage (one-half from the first amplifier and one-half from the second amplifier) and theoretically produces four times the power output (double the voltage equals double the current equals four times the power).
briole - Name for the adjustable wire ropes used for theater rigging, e.g., loudspeakers, lighting, scenery, etc.
BRIT (British Record Industry Trust) - Home of the Brit Awards; Britain's Grammy equivalent.
broadband - Also wideband, a transmission medium having a bandwidth greater than a traditional telephone (speech) channel (4 kHz). The most common broadband medium is coaxial cable carrying multiple audio, video and data channels simultaneously. Each channel takes up a different frequency on the cable. There will be guardbands, or empty spaces, between the channels to make sure each channel does not interfere with its neighbor. The most common example is the CATV cable.
broadcasting - A message sent out available for anyone to receive (just like radio broadcast), i.e., sending the same message to multiple recipients, as opposed to multicasting. Broadcasting sends a message to everyone on the network; multicasting sends a message to a specified few.
brown noise also called red noise or Brownian noise - -6 dB/oct decreasing density (most amount of low frequency energy or power; used in oceanography; power proportional to 1/frequency-squared); popcorn noise.
B&S gauge (Brown & Sharpe) - A specification for non-ferrous (e.g., copper, aluminum, gold, silver, etc.) wire diameter named after J.R. Brown who devised the system in 1857. The British standard is called SWG standing for Standard wire gauge, also called Imperial wire gauge.
BSI (British Standards Institute) - The National Standards organization responsible for coordinating standards preparation for sound equipment in the UK.
B-taper - linear taper, always 50% resistance at the 50% travel point.
BTL (bridge-tied load) - An amplifier configuration where the loudspeaker load is connected between the two hot outputs of two amplifiers operating in bridged amplifier mode, i.e., anti-phase, where the output of one amplifier drives the the second amplifier out of phase, or inverted, and operates at unity gain. Thus the second amplifier (usually the second channel of a two channel design) acts as a current amplifier (with inverting voltage). This doubles the output voltage (one-half from the first amplifier and one-half from the second amplifier) and theoretically produces four times the power output (double the voltage equals double the current equals four times the power). However this virtually never happens in practice since the amplifier power supply runs out of current long before four times the power is reached. Typically, amplifiers operating in bridged amplifier mode deliver twice their single-ended output power. Semiconductor audio power amplifiers use BTL configurations as a way to maximize power output from the small voltage sources found in internet appliances and automotive applications.
BTU (British thermal unit) - (1) The quantity of heat required to raise the temperature of one pound of water from 60° to 61°F at a constant pressure of one atmosphere. (2) The quantity of heat equal to 1/180 of the heat required to raise the temperature of one pound of water from 32° to 212°F at a constant pressure of one atmosphere. [AHD] The Btu is equivalent to 0.252 kilogram-calorie or 1055 joules. And 1 watt equals 3.41 BTUs/hour.
buck converter - A type of step-down voltage converter, used in DC-DC conversion, favored by designers for its low cost and simplicity.
buds - A special earpiece or earplug containing high quality miniature loudspeaker systems, similar to hearing aids, used for on-stage and recording studio purposes in lieu of traditional floor foldback monitors.
buffer - In data transmission, a temporary storage location for information being sent or received.
buffer amplifier - The IEEE dictionary defines buffer amplifier as "An amplifier in which the reaction of output-load-impedance variation on the input circuit is reduced to a minimum for isolation purposes." (Vacuum tube cathode followers and solid-state emitter followers are two examples.) This is a bit confusing, but one thing is clear, it says that at the most fundamental level a buffer amplifier isolates (buffers) the loading effects (impedance) of two stages. It separates them, making them independent. In analog designs, buffer amplifiers are used for just this purpose. If the next circuit stage in a design has impedance characteristics that are detrimental to the preceding stage then a buffer amplifier minimizes this interaction. And its use is not confined to analog design, digital circuits use buffers to minimize similar loading effects.
The term "amplifier" comes about from the fact that most buffer amplifiers also provide either voltage or current gain. In this sense, a normal audio power amplifier can be called a buffer amplifier - it buffers your preamp from your very low impedance loudspeakers. [Historical Note: Sometimes a buffer amplifier provides speed as well as isolation. In the mid '70s, National Semiconductor offered in their specialty hybrid circuits line, a product simply named "Fast Buffer," whose purpose was to provide impedance isolation, but could do so at high megawiggle speeds (not a trivial task back then), and if that wasn't good enough, they also offered a "Damn Fast Buffer," that could really get the job done (true story).] As can be seen, the term buffer amplifier is a bit vague: it provides isolation, that much is sure, however, it may also offer voltage gain, current gain, or both. And it may even provide an unbalanced-to-balanced function, or vice-versa. [Rane Corporation] bug - A surprisingly old word used most often to connote a problem with a program or computer. From the 1896 edition of Hawkin's New Catechism of Electricity (Theo. Audel & Co.) comes this definition: "The term `bug' is used to a limited extent to designate any fault or trouble in the connections or working of electric apparatus."
Bumbershoot - A Seattle arts festival held each Labor Day weekend, featuring over 2,500 artists including comedians, dancers, painters, poets, sculptors, tightrope walkers, acrobats, filmmakers, bookbinders, DJs, thespians, and musicians of every genre -- from classical to hip-hop.
Bundle - The shortened form for CobraNet® Bundle; always with a capital B to differentiate it from a bundle of wires.
burnt-in time code - Often abbreviated to BITC by analogy to VITC. A human-readable on-screen version of the timecode information for a piece of material superimposed on a video image. BITC is sometimes used in conjunction with "real" machine-readable timecode, but more often used in copies of original material on to a non-broadcast format such as VHS, so that the VHS copies can be traced back to their master tape and the original time codes easily located. [Wikipedia]
Burrus LED - A surface-emitting LED with a hole etched to accommodate a light-collecting fiber, named after its inventor, Charles A. Burrus of Bell Labs. [JAES]
burst error - A large number of data bits lost on the medium because of excessive damage to or obstruction on the medium.
bus - One or more electrical conductors used for transmitting signals or power from one or more sources to one or more destinations. Often used to distinguish between a single computer system (connected together by a bus) and multi-computer systems connected together by a network.
Butterworth filter - A type of electronic filter characterized by having a maximally flat magnitude response, i.e., no amplitude ripple in the passband.
Butterworth crossover - The category of loudspeaker crossover design (or alignment) based on Butterworth filters.
buzznack - An old organ, out of order and playing badly. [Kacirk]
bypass capacitor (also decoupling capacitor) - A capacitor connected from (usually) power supply lines to ground, for the purposes of diverting AC ripple voltages and currents to ground in order to keep the DC supple lines clean and quiet.
byte Abbr. B - A group of eight bits (a word) operating together. Usually abbreviated in uppercase to distinguish "byte" from "bit" which uses lowercase "b".
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HistoryOfRecording.com acknowledges the Elsevier, Inc. publication, Audio Engineering know it all, the University of Washington Press publication, The Audio Dictionary, second edition, the Howard W. Sames & Co., Inc. publication, Audio cyclopedia, the Cambridge University Press publication, The Art of Electronics, Rane Corporation (Dennis A. Bohn, CTO), Houghton Mifflin Company publication, The American Heritage Dictionary of the English Language, Fourth Edition, the IEEE publication, IEEE 100: The Authoritative Dictionary of IEEE Standards Terms, Seventh Edition and Wikipedia in the preparation of this Dictionary of Audio Terminology.
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