Glossary – S
Copy of a master recording made for protection purposes.
The condition of exceeding a tape's magnetic capacity .
The distortion created by driving a magnetic tape beyond its saturation point.
The level, beyond which any further increase in applied signal strength will cause no further increase in fluxivity.
Signal rendered higher or lower than is expected. Example, Voice sounds too loud in the front seat of a threatre. Frequency distortion often results since frequency response of the ear is different to different levels of volume. Loss of fidelity when the sounds from a large concert hall, for example, are reproduced in a small listening room.
A high-frequency filter circuit that minimizes scratchy sounds in playback of deteriorated discs.
Portion of the recorded surface where the groove pitch has been increased to mark the separation of two successive bands of recording.
A loudspeaker cabinet with no vents or ports, as in an acoustic suspension system.
Second harmonic distortion (HD2): Ratio of second-order harmonic to the input signal (carrier). Often measured as dBc.
A horn with two parallel and two diverging sides.
A trade name of the Ampex Corporation used to describe the adding of live sound to a spare track to synchronize with recordings on a multitrack tape or film by the temporary use of other tracks of the record head for replay. Sel-Sync is an abbreviation of selective synchronization.
A measure of the ability of an electronic device to select a desired signal and to reject adjacent interfering signals; also termed bandwidth.
The condition whereby a record head tends to partially erase a high level, high frequency signal as it is being recorded.
The minimum value of input signal that is required by an electronic unit, such as a tuner, to deliver a specified output signal level. The measure of a microphone's sensitivity is an indication of efficiency. A classical dynamic mike may have a sensitivity of 0.2 mV. A model giving 0.25 mV is considered sensitive and 0.1 mV is unsuitable for recording low frequencies. Condenser mikes always have a preamplifier in the mike casing otherwise their high impedance would not allow the signal to be transmitted along a cable. It is difficult to produce a very low noise preamp capable of receiving without overloading a signal given by a condenser mike placed in a strong acoustical field. For this reasonit is better to have special preamps for condenser mikes.
The degree to which one channel's information is excluded from another channel; customarily expressed in dB units.
A reel of original recorded material. It can include both master material and out-takes.
Any device used to reduce the effects of spurious electrical or magnetic fields on a signal path or system. SHIELDED CABLE -Any cable in which the conductors are protected by a surrounding braided or foil shielding. SHOCK MOUNT -A suspension system which mechanically isolates a microphone from its stand or boom, thus protecting the microphone against mechanical vibrations.
Exaggerated hissing and/or distortion in voice patterns. Often produced by the presence of high energy level in words containing 's' sounds.
A description of those consonants that are uttered with an 's' sound. (s, z, sh, zh, etc.)
The form of variation with time of a wave whereby information, message, or effect is conveyed in communication.
A block diagram of a recording console or other audio system, showing the various possible signal paths through the system, but not detailing the actual electronic components making up each part of the system.
A test instrument whose output may be one or another of the following; sine wave, square wave, sawtooth, ramp voltage, etc.
An audio system (equalizer, compressor, expander, et al) used to modify some characteristic of the signal passing through it.
The process of devising a signal path through a console or other audio system, using bus assignment switches, or patch cords.
Proportion of amplitudes (intensity) of the wanted signal to the unwanted noise in an electrical transmission system. It sets an upper limit to the dynamic range of the system. Customarily expressed in dB units. This ratio is expressed in many different ways, for example, in terms of peak values in the case of impulsive noise and in terms of root-mean-square values in the case of random noise, the signal being assumed sinusoidal (see also Weighted noise).
Graphical representation of simple harmonic motion.
A sudden displacement of a stylus from one groove to another groove.
A deflection of a tape, as it passes over an improperly aligned head or tape guide.
An audibly distracting echo from a reflective surface in a room.
Term used for recording spoken 'take' numbers or cues on tape by analogy with the chalked numbers on a film clapperboard.
Recording of an announcement of the take number at the beginning of a recording.
1. Steepness of the sloping part of a response curve: usually stated in dB/octave. 2. A plotted slope derived from input and output amplitudes and stated as a ratio (e.g. 1 to 1 a conventional amplifier, 20 to 1 a limiter).
A speaker design without inherent springiness; it utilizes the reaction of a trapped backwave for restorative force.
Form of electromagnet permitting remote operation of switches etc.
On a recording console's input module, a switch that turns off the normal monitor system, and instead routes the appropriate input signal directly to the monitor.
A unit of loudness. A simple l-kHz tone, 40 dB above a listener's threshold, produces a loudness of 1 sone. The loudness of any sound that is judged by the listener to be n times that of the 1 sone tone is n sones.
Also called a sound wave. An alteration in pressure, stress, particle displacement, or velocity, propagated in an elastic medium. Also called a sound sensation. The auditory sensation evoked by a sound wave.
The conversion of sound energy into some other form (usually heat) in passing through a medium or on striking a surface.
The incident sound energy absorbed by a surface or a medium, expressed as a fraction.
A method in which previously recorded material on one track may be re-recorded on another track while simultaneously adding new material.
Sound pressure measurement in decibels. In decibels, 20 times the logarithm of the ratio of the pressure of a sound to the reference pressure, which must be explicitly stated. Also, the pressure of an acoustic wave stated in terms of dynes per square centimeter or microbars.
Also called acoustical repectivity. Ratio at which the sound energy reflected from a surface hows on the side of incidence to the incident rate of flow.
A combination of transducers and associated equipment for reproducing prerecorded sound.
The frequency components included within the range of audible sound.
An electroacoustic transducer that radiates acoustic power into the air.
Ratio of the total useful sound radiated from a speaker at any frequency to the electrical power applied to the voice coil.
The rated impedance of the voice coil in a speaker.
A combination of one or more speakers and all associated baffles, horns, and dividing networks used to couple together the driving electric circuit and the acoustic medium
In a moving-coil speaker, the component that is moved back and forth in response to the applied audio voltage.
Also called unit-area acoustic impedance. The complex ratio of sound pressure to particle velocity at a point in a medium.
The imaginary component of the specific acoustic impedance.
The real component of the specific acoustic impedance.
A distribution of frequencies. For example, the frequencies within the audio bandwidth may be called the audio frequency spectrum.
How closely a turntable or tape deck maintains the standard speeds.
770 mi/hr. Velocity of sound in the open is influenced by air temperature more than by atmospheric pressure. At 21 degrees C, speed is 344 m/sec (1,100 ft/sec); at 50 degrees C, 360 4m/sec, or 42 ft/sec faster.
The point at which two pieces of magnetic tape are joined together, as in editing.
A device used for positioning and holding down a section of magnetic tape while making splices.
Special dry adhesive tape used in butt editing of tape recordings.
Any network that enables a signal to be routed to two or more separate outputs.
An artificial reverberation system using springs to simulate the sound of natural reverberation.
A midrange speaker.
Metal negative, produced from the positive or mother and used for the production of pressings. From each mother up to six negative stampers are produced. These are chromium-plated to make them harder and to give the pressings a shiny surface. The next step is the Pressing of new records.
A specified reference level. In recording applications, standard operating level is defined as O VU = + 4 dBm. In broadcasting, O VU = + 8 dBm:
Reflected waves that alternately cancel and reinforce at various distances. An interference pattern characterized by stationary nodes and antinodes. Tubby sound in a small room of booth from low frequency and poor response--caused by long waves with short reflection pattern. Almost all sound present goes directly into the mike producing "unnatural" sound presence.
A signal processing device whose operating parameters are not affected by the signal passing through the device. See Dynamic Signal Processing Device.
A standing wave.
An artificial reverberation system using a steel plate to simulate the sound of natural reverberation.
The solid angle which, on a sphere, encloses a surface equal to the square of the radius of the sphere.
A system wherein sound energy that is picked up by two separated microphones is recorded on separate channels and is then played back through separate channels that drive individual speakers.
A process designed to produce the illusion of a spatial distribution of sound sources, by the use of two or more channels of information.
A stereo recording made with two bi-directional microphones whose axes are at 90 degrees to each other. The microphones are usually aimed at the extreme right and left edges of the sound source to be recorded.
The maximum instantaneous rate of volume displacement produced by the source when emitting a sinusoidal wave.
A cardboard or plastic disc with a specialized printed design suitable for checking turntable speed.
Same as phonograph needle. Generally diamond or sapphire tipped, in a cutter head or pickup cartridge.
The major radius which sits across the groove is similar to that of the spherical stylus and so it maintains the correct position on the groove walls; but the minor radius can trace shorter wavelengths. For a 0.3 mil minor radius the contact span is 0.42 mil. Corresponding half-wavelength frequencies are 23.6 Hz for the start and 11.4 Hz for the end of the disc, at which it will trace amplitudes up to 0.084 mil. As the styli are closer to the shape of the cutter there is less pinch effect. Second harmonic distortion is thereby lower, averaging 4.0% at 8 KHz with 5 cm/sec recorded velocity. While pinch effect is less and high frequency tracing is better with a smaller minor radius, the area of contact is also smaller, and this puts greater pressure on the groove wall for a given tracking force. Small radii should thus only be used with cartridges having low tracking force.
A triangular chisel shape stylus used to produce a master disc. The cutting stylus was inclined from the vertical by 15 degrees from 1964-197?, and 20 degrees since then according to the IEC standard. However. a +5 tolerance is permitted. Owing to the elasticity of the disc material, there is a springback effect after the cutter has passed. This reduces the tracking angle which together with the tolerance means that the angle can differ considerably from one record to another. The cutter traverses the dise tangentially, in a straight line from disc edge to centre. The cutter response is termed constant velocity, which means its velocity is the same for all frequencies. The amplitude therefore increases as the frequency drops, at the rate of 6 dB/octave. Large low-frequency stylus excursions are avoided by cutting the bass while treble is boosted to improve signal to noise ratio. These contours roll off either side of a short flat region centred on 1 kHz, to form the RIAA recording characteristic.
The recording cutter head forms a tangent with all parts of the record groove by moving across the disc in a straight line, whereas the reproducing pickup traverses it in an arc. The axis of motion of the stylus is thus different to that of the cutter over a large portion of the disc surface. This is lateral tracking error, which produces second harmonic and intermodulation distortion.
This is a sum of the actual mass of the stylus, the cantilever and that of the cartridge's moving parts divided by the leverage ratio of the cantilever. Approximate proportions of each can be: 10%, 60%, and 30% respectively. This mass must be accelerated by the record groove to values up to 1000 g at which the vinyl can flow as liquid. Permanent groove deformation is proportional to mass and inversely proportional to stylus contact area. The stylus resonance which should be above the cartridge frequency range, is governed by its mass reacting with the groove elasticity. The lower the mass the higher the resonance. Most quality cartridges have a lower stylus mass than 0.5 mg, but under O. 15 mg has been achieved.
Sapphire has given way to diamond tips mounted in metal shanks welded to the cantilever. Acceleration of up to 1000 gravities requires a very low stylus mass. So as metal adds mass, some are made of pure diamond mounted directly, and are called naked diamond styli.
Adequate contact area is maintained with a small minor radius. Contact area radius increases from the tip to the shank.
These use a parabola instead of a cone shape and so achieve a contact area four times greater than that of the spherical stylus. This improves tracking, reduces wear and doubles the stylus resonant frequency.
If the major axis of an elliptical stylus is not in perfect line with the disc radius, one side will be slightly ahead of the other in the groove. Spurious phase differences between channels will thus result, degrading the stereo image. These are not produced by a spherical stylus. Skew is caused by incorrect mounting of the stylus on its cantilever (manufacturing tolerance is +3 degrees), an off-centre cantilever. and lateral tracking error.
The most common stylus for low-cost players is cone-shaped with a spherical point having a radius of 0.6-0.7 mil (15-18 microns). While placing the stylus at an optimum position halfway up the groove walls, its contact span is too large to follow short wavelengths. When the span equals a half-wavelength it will trace an amplitude of up to 0.2 of that half-wavelength. The contact span is 1.4 times the tip radius, so for a 0.7 mil radius it is 0.98 mil. Frequencies corresponding to this half-wavelength are 9.8 KHz for the start, and 48 KHz for the end of the disc. Higher frequencies can be traced but at lower amplitudes. As the disc cutter is triangular, the groove width is narrower at the sides of the recorded wave than at the top and bottom. Thus the stylus is squeezed into spurious vertical motion twice for each cycle, so producing second harmonic distortion. An average of 6.4% harmonic distortion is produced at 8 KHz with 5 cm/sec recorded velocity. This is called pinch effect.
For distortionless translation of the groove modulations into electrical signals, the reproducing stylus should follow exactly the same path at the same angle as the recording cutter. A number of factors make this ideal unattainable in practice.
Wedge-shaped from the side, but mitre-shaped from the front. The almost straight sides achieve contact over most of the wall surface, with a contact area radius of only 0. 14 mil (3.5 Gun) giving a theoretical 70 KHz tracing ability at the disc centre.
In following the vertical groove modulations the stylus describes an arc about a fulcrum formed by the anchored end of the cantilever. To clear the disc surface the fulcrum must be raised above it, hence the arc is tilted forward. This is known as the tracking angle, and should correspond with the angle of inclination of the recording cutter, termed the slant angle. Deviations from the now standard 20 degree recorded slant-angle are common due to manufacturing tolerances of +5% and lacquer springback (the partial restoration of the disc lacquer contour after the cutter has passed, due to its elasticity). Cartridge tracking angles are not always accurate. The result is vertical tracking error which produces mainly second harmonic and intermodulation distortion.
An integral submultiple of the fundamental frequency in a tonal waveform.
As judged by the senses. Opposite to objective, i.e. measured.
Any tape used in the production of a master tape. For example, if a master tape is an equalized (or otherwise processed) copy of an earlier tape, the earlier tape is called the sub-master.
A fundamental frequency that has less amplitude than one or more of the associated harmonics.
A speaker designed to reproduce the highest frequencies in the audio range.
On a tape recorder, the reel from which tape winds, as it passes the head assembly.
On a tape recorder, the motor that is used to supply hold-back tension to the tape on the supply reel and to rewind the tape.
A recording session during which brass, chorus, etc. may be added to a previously recorded tape, usually containing basic rhythm tracks.
Record in which the hole is not at the exact center of the groove spiral.
The output of the sync head, in the Sel-Sync mode
Device used in electronic music giving flexible control of the pitch, timing, and tonal quality of signals.