A-B TEST ------Direct comparison of sound quality between hi-fi components accomplished by switching from one to another.

ACOUSTIC FEEDBACK ------The howling caused when a microphone picks up vibrations from its own speaker system.

AMPLIFY ------To increase levels, as with a volume control.

ATTENUATE ------To decrease levels, as with a volume control.

AUTOMATIC SHUT-OFF------A special switch on a tape recorder which automatically stops the machine when the tape breaks or runs out.

AZIMUTH ADJUSTMENT------The adjustment to position the head gap exactly perpendicular to the horizontal base of the tape.

BAFFLE ------The panel to which most speakers are mounted, usually the front panel of an enclosure.

BIAS------A high frequency alternating current fed into the recording circuit and used as a carrier of the audio signals to the record head, as well as current to the erase head.

BINAURAL SOUND ------Two-channel sound, in which each channel recorded is heard only through one ear. (Channel 1—left ear, and Channel 2—right ear.)

BINAURAL MONITOR JACK------Output jack of tape recorder wired to accept binaural earphones.

BULK ERASER------A strong alternating electro-magnetic device used to erase the magnetic patterns on tape while still wound on a reel, or in bulk form.

CAPSTAN------The rotating shaft which engages the tape and pulls it across the heads at constant speed.

CATHODE FOLLOWER ------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 frequency. Usually not necessary in a normal installation.

CHANNEL------Complete sound or signal path of a sound system.

CHASSIS------The metal base of frame which carries the electrical or mechanical assemblies.

CPS------Cycles per second.

CROSS TALK------Signal (sound) leakage between two channels.

DECIBEL (ABBREVIATED db)------A relative measure of sound intensity. One db is the smallest change in sound volume that the human ear can detect.

DISTORTION------Any difference between the original sound and the recorded and reproduced sound.

DUAL TRACK RECORDER ------Type of monophonic recorder which records or plays back half of a standard 1/4" tape in one direction and the other half in the opposite direction.

DUBBING ------The art of duplicating on tape.

DYNAMIC MICROPHONE------An electro-magnetic type which employs a moving coil in the magnetic field.

DYNAMIC RANGE------The ratio between the softest and loudest sounds a tape recorder can reproduce without distortion.

EDITING ------Selection of certain sections of tape recordings and the deletion of unwanted portions and then splicing them together in the desired sequence.

EQUALIZATION ------The manipulation of frequencies that are required to meet the recognized standards of recording and reproducing techniques.

ERASE HEAD ------The magnetic assembly on a tape recorder over which the tape passes to remove previously recorded signals.

FAST FORWARD ------Provision in a tape recorder to run tape rapidly forward through the machine for quick selection of desired portion.

FEED REEL------The reel on a tape recorder which supplies the tape.

FLAT RESPONSE ------Any audio system is specified as having an essentially flat frequency response if it is rated plus or minus 3 db from 50 to 14,000 cps.

FLUTTER------Very short and rapid variations in tape speed.

FOOT SWITCH------A mechanical foot pedal for stopping and starting a tape recorder without the use of hands.

FREQUENCY ------The rate of repetition in cycles per second (cps) of musical pitch, as well as of electrical signals. Low frequencies refer to bass tone, high frequencies to treble tone.

FREQUENCY RESPONSE ------(See Flat Response.)

FM "Frequency Modulation"------FM broadcasting is characterized by wide range audio response and a great deal of freedom from noise.

FM STEREO ------Also known as multiplexing. A form of FM broadcasting in which two channels of audio signals are transmitted on the same carrier, offering a signal similar to the stereo available from stereo records and tapes.

GAIN------The increase in signal provided by an amplifier between input level and output level.

GAP ------The tiny distance between the poles of tape heads usually measured in microns.

GROUND ------A point in any electrical system that has zero voltage, usually the chassis of any electrical component.

HEAD------An electro-magnetic device across which the tape is drawn and which magnetizes the iron oxide coating of tape.

HEAD ALIGNMENT ------In tape recorders, the correct position of the tape head and gap, with respect to the magnetic tape.

HEADPHONES ------Small sound reproducers in a suitable frame for wearing about the head. Close coupled to the ears for private listening.

HUM------Low frequency noise in an audio component usually induced from the power line or stray magnetic fields.

Hz------Hertz: cycles per second.

IHF------The Institute of High Fidelity, the official association of the manufacturers and certain related organizations in the high fidelity field.

IMPEDANCE ------Measured in ohms, it is the AC resistance of any electrical system. Generally referred to as either "high" or "low" impedance. For best results in connecting two components, output and input impedances must match.

IN-LINE HEADS ------Arrangement of stereophonic heads on a tape recorder in which the head gaps are mounted one directly above the other. Also called "stacked heads".

INPUT------The receptacle or jack through which a signal is fed into an amplifier.

IPS ------Abbreviation for tape speed in inches per second.

INVERTER ------A device to change one type of electrical current to another. Frequently used to obtain 1 1 0 volts alternating current for operation of a tape recorder in an automobile.

JACK ------Receptacle or plug connector leading to the input or output circuit of a tape recorder or other component.

LEVEL INDICATOR -----Indicates the level at which the recording is being made and serves as a warning against under recording or over recording. It may be in the form of a neon bulb, "Magic Eye" or a VU meter.

LOUDNESS CONTROL ------Sometimes known as "contour". Compensates for loss of tones at the extreme end of the audio range when listening at soft volumes or through small speakers. A typical control of this sort will usually boost the bass.

MAGNETIC TAPE ------Usually 1/4" plastic tape which has been coated with an emulsion of iron oxide particles. Used on tape recorders as the recording media and is the highest fidelity of reproduction possible today.

MIL ------1/1,000 of an inch. Tape thickness is usually measured in mils.

MIXER------A device by which signals from two or more sources can be combined and fed simultaneously into a tape recorder at the proper level and balance.

MIXING ------The blending of two or more signals for special effects.

MONITOR HEAD ------The head on a tape recorder which, when connected to the proper circuitry, makes it possible to listen to the material directly off the tape while the recording is being made.

MONOPHONIC RECORDER ------Sometimes incorrectly called monaural recorder. It is capable of only one channel recording.

MULTIPLEX ------(See FM Stereo.)

NAB CURVE ------Standard playback equalization curve set by the National Association of Broadcasters.

OSCILLOSCOPE ------A device which forms a graphic representation of an electrical signal on a screen (cathode ray tube). Used for testing and measuring of electrical and electronic equipment (tape recorders).

OUTPUT ------The signal voltage coming from components, such as pre-amplifiers and amplifiers. In tape recorders, there are line outputs, speaker outputs and monitor outputs.

OXIDE ------As used in magnetic tape—a microscopic ferrous oxide.

PATCH CORD ------A short cable with a plug at either end used to interconnect equipment, such as tape recorders and amplifiers.

PHASING ------The proper polarity orientation of the two speakers used in stereo playback; proper phasing would be, for example, the ground connection being common to both speakers.

PINCH ROLLER (Pressure Roller)------A rubber roller which engages the capstan and pulls the tape with constant speed and prevents slippage.

PLAYBACK ------Reproduction of the sound previously recorded on the tape.

PLAYBACK HEAD ------The magnetic head which picks up signals from tape for playback.

PLUG ------A form of mechanical interconnect used for quick and easy connection of components, such as phone plug, phono plug and AC plug.

POWER AMPLIFIER------An amplifier designed to operate a speaker system.

POWER CORD ------Cable used to connect a tape recorder to AC current.

PRE-AMPLIFIER ------An amplifier that boosts extremely weak signal voltages, such as those from microphones, magnetic playback heads or phonograph pickups, to a level that is usable by power amplifiers, and at the same time accomplishes the necessary equalization for industry standards.

PRE-RECORDED TAPES-----Recordings on tape that are commercially available.

PRESSURE PADS------Felt pads mounted on arms which hold the magnetic tape in close contact with the heads. Mostly always used in "one-motor" tape recorders.

SIGNAL-TO-NOISE RATIO------The ratio, measured in db's, between the pure sound and the noise induced by the recording system itself.

SOUND-ON-SOUND------A method in which previously recorded material on one track may be re-recorded onanother track while simultaneously adding new material.

SPLICING TAPE------A special pressure sensitive non-magnetic tape used for splicing magnetic tape.

STACKED HEADS------(See In-Line Heads.)

STEREOPHONIC SOUND ------"Dimensional" sound reproduction achieved through the use of two or more sound tracks recorded through microphones so placed as to provide separation of sounds and heard simultaneously through speakers arranged somewhat apart from each other, according to the size of the room in which it is played.

TAKE-UP REEL------The reel located on the right side of the tape recorder which accumulates the tape as it is recorded or played.

TAPE DECK ------A tape recorder designed for use in built-in high fidelity music systems. It is encased in a metal cage rather than a carrying case. The electronics usually consist of record amplifiers and playback preamplifier.

TAPE GUIDES------Grooved metal posts located on either side of the head assembly to keep the tape tracking properly across the heads.

TAPE INDEX COUNTER------A digital counter used mostly to aid in referring to a particular portion of tape.

TAPE SPEED ------The speed at which tape moves past the heads and measured in inches per second.

TAPE SPLICER------A semi-automatic or automatic device used for splicing tape.

TAPE TRANSPORT------The mechanical portion of the tape recorder mounted with motors, reel spindles, heads and controls. It does not include pre-amplifiers, power amplifiers, speakers or carrying case.

TONE CONTROL------Used to vary bass and treble response to achieve individually desired balance of tone.

VU METER ------A volume unit meter which indicates the relative levels of sounds being recorded.

WOW------Repetitive slow variations in tape speed.