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acetate: Term erroneously used to designate instantaneous discs. automatic equalizer: Device which automatically compensates for loss in high-frequency response due to diminishing groove diameter as cutter moves inward. blank: The disc before it is cut. center pin: Pin at center of turntable which passes through center hole of disc. center post: The end support of lathe mechanisms which is placed over the center pin. chip: The thread of disc coating material which is dug out by the stylus. christmas tree pattern: See light pattern. constant amplitude: Method of recording in which groove width is the same at all frequencies with constant cutter voltage. constant velocity: Method of recording where groove width decreases with rising frequency with constant cutter voltage. crossover frequency: See turnover frequency. cut: (Verb) To make a recording. (Noun) A recording. cutter: Device which converts electrical (audio) energy to movement of stylus; counterpart of the phono pickup used for playback. cutting angle: Vertical angle cutting face of stylus makes with disc surface on forward side. Should normally be exactly 90 degrees, but may be very slightly less, never more. cutting head: See cutter. depth of cut: Distance of vertical penetration of stylus into disc coating material, governed by weight applied to cutter. This determines also the lateral dimension of the groove, and the amount dubbing: Duplication of all or part of material on one disc, by playing it through pickup and amplifier into cutter and recording on a new disc. See Fig. 1301. See also re-recording. dummy load: A resistor which temporarily replaces a reactive load, such as a loudspeaker or cutter, and is of the same impedance. Used for measurement purposes to avoid changes in meter readings due to varying reactance of normal load. equalization: Deliberate alteration of frequency response for some specific purpose. feed mechanism: Mechanical assembly which carries cutter across disc during recording. Term means entire unit, including guide rods, feed screw, center and outside posts, etc. feed screw: Threaded rod of feed mechanism which revolves in synchronism with turntable and pushes cutter across disc during recording. fidelity: Likeness between original and reproduced sounds. Not to be con fused with quality, which denotes pleasing tone of reproduced sound, but may or may not be an accurate likeness of the original. governor: Device which regulates the speed of nonsynchronous motors. groove: The spiral track cut into the disc coating material, path of which is varied in accordance with modulation. groove width: The amount of lateral variation in the path of the groove caused by modulation. idler: Rubber-rimmed wheel used in rim-driven turntables to transmit motor shaft movement to turntable. instantaneous recording: Record which may be played back immediately after it is cut, without further processing. land: Band of uncut record surface between adjacent grooves. See Fig. 703. lateral recording: Recording method in which modulation causes variations in the lateral path of the groove. See groove width. lathe: Overhead-type feed mechanism as distinguished from a swinging-arm type mechanism. lead screw: See feed screw. light pattern: See Fig. 1103, in Section 11 and accompanying text. lock groove: Groove at end of cut designed to prevent pickup from flying off. The lock groove is a perfect circle rather than a spiral. See Fig. 1206. modified constant velocity: Most used recording method. Constant amplitude is employed up to a selected turnover frequency and constant velocity above that frequency. monitor amplifier: Amplifier and associated loudspeaker used to listen to material being recorded, as distinguished from recording amplifier which feeds cutter only. pattern: Visible results, on finished discs, because of improper adjustments of the recording system or inferior components. See Figs. 1103 and 1401. pinch effect: Narrowing of portions of grooves at small cutting diameters near center of disc, which reduces high-frequency response and increases distortion in playback. Important only in 33 1 /3-r.p.m. recording. See Fig. 1109. pitch: (General) Frequency of sound. (Recording) Number of grooves cut per inch. pre-emphasis: Progressive boosting of frequencies at one end of range (usually high end) during recording. A form of equalization. pressing: Method of duplicating records in large quantity; a manufacturing process. Term also used to refer to a record made by the pressing process. re-recording: Duplication of an entire disc by playing it into recording amplifier and recording on a new disc. See dubbing. rolloff: Progressive attenuation of frequencies at one end of range. The re verse of pre-emphasis. rumble: Low-frequency noise heard in record playback, caused by motor vibration in cutting or playback turntable. sapphire: Very hard and smooth precious (or synthetic) stone used as tip material in best (and most expensive) styli. shellac: Gritty, brittle material of which most phonograph records are made. spiral: (Noun) Path of grooves during recording. (Verb) Process of separating different selections on same disc by momentarily greatly decreasing the cutting pitch. stellite: A metallic alloy used as tip material in medium-priced styli. stroboscope disc: Disc printed with radial lines, used in checking turntable speed. stylus: Cutting tool. synchronous motor: One whose speed is governed by power-line frequency. thread: See chip. tone control: Equalizer device used in phonographs to allow listener to attenuate or boost low or high frequencies. tracking error: Failure of the stylus cutting face surface to coincide with a disc radius drawn through the stylus. Error exists when face cuts radius at an angle. Occurs with swinging arm feed mechanisms. transition frequency: See turnover frequency. turnover frequency: Frequency at which constant amplitude changes to constant velocity response in modified constant velocity records. Usually between 250 and 1.000 cycles. vertical recording: Recording method wherein modulation varies groove depths. vinylite: Smooth, flexible material of which certain pressings are made. volume indicator: Meter, neon light, or "magic eye" tube which visually indicates maximum allowable cutting level. wow: Wavering of musical tones caused by variations in turntable speed in recording or playback. |