Glossary – C
Comite Consultatif International Radio (International Radio Consultive Committee).
A speaker enclosure designed for operation with an electronic organ.
The severe attenuation that occurs when two identical signals of opposite polarity are combined.
Colloquial for headphones.
Part of the cartridge-stylus assembly. These can contribute up to 60% of the effective mass, so materials must have a low mass yet be very rigid. Some of these in order of merit are: tubular aluminium, beryllium, sapphire, boron. Owing to the leverage ratio, a short cantilever transmits a large movement to the generators and vice-versa, but the ratio reflects the mechanical effect of the load. So small cantilevers give a large output but also have a large effective mass.
The ability of an electrical component (or components) to store electric charges. Charges present in a conductor attract opposite charges to nearby but not electrically connected conductors. A signal may therefore cross between one component and another, between which there is no direct path. Capacitors are used in systems for coupling, smoothing, and tuning purposes. In lines, capacitance is the reason for loss of signal; this varies with distance between plates or components. Parallel conductors in a signal line may take on the properties of a capacitor, thereby attenuating high frequencies. Stray capacitances from the mains are the cause of the ac Hum, which is transferred unintentionally from component to component.
Any device designed for storage of electrostatic field energy. Parallel conductors in a signal line may take on the properties of a capacitor, thereby attenuating high frequencies.
Sometimes called Condenser or Electrostatic. Type of microphone in which the signal is generated by the variation in capacitance between the diaphragm(s) and a fixed plate.
The spindle or shaft of a tape transport mechanism that pulls the tape past the heads.
The rubber coated wheel that forces the tape against the capstan when the tape recorder is in the play mode. Also called a pinch roller or puck.
The motor that drives the capstan. The capstan is often the extended shaft of the capstan motor.
An FM tuner's ability to reject unwanted co-channel signals. If an undesired signal is more than 2.2 dB lower than a desired signal, the undesired signal will be completely rejected.
Microphone with a semiheart-shaped polar diagram.
A heart-shaped directional pickup pattern for a microphone that assists in reducing background noise.
The wave which is intended to be modulated.
1. A transducer device used with a turntable to convert mechanical channels in a disc into electrical impulses. 2. Easy-loading magazine of magnetic tape.
The inductance of the cartridge combined with the capacitance of the screened lead forms a resonant circuit that can produce a peak in the upper part of the frequency response. It can be flattened by critical resistive damping, or pushed above the audio range with low values of inductance and capacitance. As sufficiently low values are hard to get in practice, damping is applied using a load resistor. Its value is effective for only one combination of inductance and capacitance, so as the inductance is fixed, and the load is standardised at 47 kh2 with few exceptions, the specified capacitance must be observed. While some low-noise and data-screened cables have capacitances around 100 pF/m, most usually used for pickup connection go up to 350 pF/m. As some cartridge makers specify 100 pF, care must be taken in selecting and measuring the screened cable.
Usually quoted for a recorded velocity of 5 cm/s at 1 KHz.
Preloaded container with tape and spools for use on cassette tape recorders. Actually, it is a miniature reel-to-reel tape system. Generally refers to the Philips Compact Cassette format.
The type of electronic circuit used in an output stage of a recorder to permit the use of longer interconnecting cables without the loss of high frequencies.
A test instrument, providing a visual display of the waveform being measured.
A plastic film, used as a base material in the production of magnetic recording tape.
In a peaking equalizer, the frequency at which maximum boost (or attenuation) occurs.
The electrical center of a transformer winding.
When two identical precision resistors are wired in series across a transformer winding, the point at which the resistors are joined together becomes the electrical equivalent of the actual center tap.
A standard position for the placement of the audio signal on double perforation magnetic film, in a narrow band centered between the two edges of the film.
A piezoelectric element that is used as the basis of some phonograph pickups; it generates a potential difference when stressed or strained.
A record-playing device that automatically accepts and plays up to 10 or 12 discs sequentially.
A complete sound path. A monophonic system has one channel, a stereophonic system has two, and a quadraphonic system has four. Monophonic material may be played through a stereophonic system, and quadraphonic material may be played through a stereophonic system. An amplifier may have several inputs, such as microphone(s), tuner; mono, stereo, and quad tape; and phono.
Equal response from left and right channels of a stereo amplifier. Unbalance causes sideways displacement of the stereo image. In turntable cartridges, balance difference is usually less than 2 dB. A balance control in a stereo amplifier permits adjustment for uniform sound volume from both speakers or a hi-fi system.
Signal from one channel appears in the other owing to mechanical (record players) and inductive coupling. The figure indicates the amount of attenuation in the opposite channel at 1 KHz. in record players, separation is about 6 dB less at 10 kHz, and falls also in the bass. Poor separation blurs the stereo image. Normal range for a turntable cartridge is 20-35 dB.
A transient enhancement of certain harmonics in an electronic-organ voice to simulate the timbre of a pipe-organ voice.
Magnetic tape coating permitting higher levels at high frequencies than the conventional ferric oxide.
System for simultaneously giving an identification to the picture camera and an audible and visual synchronizing point at the start or finish of a filmed section or "take".
Version of a program signal which omits one source (e.g. voice, to allow overdubbing in another language etc.).
A device for removing fast transients above a prescribed level. Normally used in conjunction with a limiter if it is to be inaudible.
Form of distortion due to severe overloading.
The technique of placing microphones extremely close to the instruments they are picking up, thereby eliminating almost all but the direct sound of the instrument(s).
A tape transport system in which the tape passes through two capstan/capstan idler systems; one on each side of the head assembly. Called an Isoloop system by the 3M Company.
The ability of the brain to pick out one conversation from many going on simultaneously.
The field strength required to bring a saturated tape to complete erasure. Coercivity is measured in oersteds.
The instantaneous polarity relationship between two complex sound waves.
Two complex waveforms that are most of the time of the same polarity.
Refers to microphone arrangements in stereophony. Two microphones are said to be coincident if they are placed immediately adjacent to each other on the same vertical axis so that any differences in the times of arrival of the sound are negligible.
Change in frequency response caused by resonance peaks.
An amplifier at which the outputs of two or more signal paths are mixed together, to feed a single track of a tape recorder.
A resistive network at which the outputs of two or more signal paths are mixed together, to feed a single track of a tape recorder.
A contraction of compressor/expander, often used in describing the action of a noise reduction system.
A combination of a compressor at one point in a communication path for reducing the volume range of signals, followed by an expander at another point for restoring the original volume range. Usually its purpose is to improve the ratio of the signal to the interference entering in the path between the compressor and expander.
A fixed or variable circuit built into a preamplifier that compensates for bass and treble alterations that were made during the recording process.
A signal processing technique, in which some processing is done before recording, with equal-and-opposite (complementary) processing during playback. Well known examples are noise reduction systems and tape recorder pre-and post-emphasis. See Non-Complementary Signal Processing.
An audio waveform composed of a fundamental frequency and a number of integrally related harmonic frequencies (a pitch and a number of related overtones).
Physical freedom from rigidity that permits a stylus to track a record groove precisely, or of a speaker to respond to an audio signal precisely. The opposite of stiffness. In turntable cartridges, compliance depends on the elasticity of the stylus damping which varies with temperature. Butyl-rubber, used in most cartridges, can increase compliance by up to 50% for a temperature rise from 68 degrees F to 95 degrees F, and decrease it by 50% for a temperature drop from 68 degrees F to 40 degrees F. Other materials have been developed that are less temperature conscious. The low-frequency arm resonance is determined by its mass reacting with the stylus compliance. High compliance needs a low arm mass to place the resonance at the optimum frequency. At one time high compliance was considered a factor of how good a cartridge is, but too high a compliance is undesirable, and it is far less important than stylus mass.
The function of a compressor that transfers a wave motion from its input to its output and at the same time reduces the span of amplitudes of the wave motion.
A loudspeaker transducer with a relatively narrow throat, designed for maximum efficiency coupling with a horn assembly.
The process of forming a disc by compressing a quantity of suitable plastic in a cavity.
In a compressor, the ratio of dB change in input level to dB change in output level.
An amplifier whose gain decreases as its input level is increased. A compressor avoids overloading the tape on loud signals. A threshold control sets the starting level below which the signal is unaffected. A slope control selects the degree of compression. Thus a 2:1 ratio reduces signals above the threshold by a half; a 4:1 by a quarter.
A compressor that acts on an entire program, rather than on a single instrument or track.
A speech-actuated compressor, in which an announcer's voice automatically drops the level of the regular program. Often used in broadcasting and paging systems.
The instantaneous crowding together of air particles during the positive half cycle of a sound wave. The opposite of rarefaction.
The diaphragm that sets the air in motion to generate a sound wave in a direct-radiator speaker; usually conical in shape.
A horn, the cross section of which increases as the square of its axial length.
The enclosure containing the various input, output, signal routing, and monitoring controls required for recording.
A microphone which is directly attached to an instrument. Generally, it responds to the mechanical vibrations of the instrument to which it is attached.
Same as integrated amplifier.
Comite Consultatif International des Radiocommunications. An international standards organization.
A super- or hyper-cardioid microphone.
A unit of electrical charge; quantity of excess electrons.
The transfer of energy from one system to another. Often used to describe the interface between a loudspeaker and the surrounding air.
Abbreviation for cycles per second; see hertz, cycle, and cycles per second.
The distance from a sound source at which the level of the direct and the reverberant field are equal.
Abbreviation for chromium-dioxide magnetic recording tape. This coating permits higher recording levels at high frequencies than the conventional ferric oxide coating.
The gradual mix between sound sources accomplished through the simultaneous manipulation of two or more "open" faders. Both fade pots are preset at a ratio to each other rather than fading down one completely. By keeping both open, the fade movement cannot be detected and the transition is smooth and blended.
The frequency at which a signal is split in order to feed separate parts of a loudspeaker. Crossover network is the filter that accomplishes this slitting.
Distortion that occurs in a push-pull amplifier at the points of operation where the signals cross over the zero axis.
1. In reference to electrical dividing networks, the audio frequency at which equal power is delivered to each of the channels or speakers. 2. The single frequency at which both sides of a crossover network are down 3dB.
Filtering circuit that selects and passes certain ranges of audio frequencies to the speakers that are designed for the particular ranges.
In stereo high-fidelity equipment, crosstalk signifies the amount of left-channel signal that leaks into the right channel, and vice versa. In magnetic recording heads is caused by magnetic coupling and the transformer action between head coil windings. In reproducing heads the cause is due to leakage between windings and the fringing effect at low frequencies (induction).
A natural piezoelectric element that is used in some phono pickup cartridges and microphones.
A speaker in which piezoelectric action is used to produce mechanical displacement. Also termed a piezoelectric loudspeaker.
That part of the console, plus associated circuitry, by which the engineer may route a headphone monitor feed to musicians in the studio. Also known as foldback.
1. In voice-over or other post recording situations, the marking of the cue-print in a way which will permit a signal to be given to the narrator to begin each portion of narration at the appropriate time. 2. Any system used by a second person to signal a narrator during narration recording.
The rate of flow of electricity, measured in amperes.
In a high- or low-pass filter, the frequency at which the output level has fallen by 3 dB.
An on-off switch in a signal path which interrupts the signal flow. Commonly found in each input module on a recording console.
One complete reversal of an alternating current, including a rise to maximum in one direction, a return to zero, a rise to maximum in the other direction, and another return to zero. The number of cycles occurring in 1 second is defined as the frequency of an alternating current. The word cycle is commonly interpreted to mean cycles per second, in which it is a measure of frequency. The preferred term is hertz.
An absolute unit for measuring the frequency or "pitch" of a sound, various forms of electromagnetic radiation, and alternating electric current. See hertz.
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"Thank you very much for the prompt service and above all the excellence in which the transfers were made. You accomplished what I thought might be impossible; transferring recordings made back in the 1940's on home made equipment to a CD. We can now hear and enjoy the voices/music that was such a large part of our lives 60+ years ago. Incredible!"