Glossary – E
A wave that has been reflected or otherwise returned with sufficient magnitude and delay to be perceived in some form as a wave distinct from that directly transmitted.
An older method of adding reverberation to a sound recording used a reverberant room, containing only a microphone and a loudspeaker, through which an output from a studio or hall was passed in order to allow a variable degree of reverberation to be added to the direct output from the same source. The microphone output was combined with the output of the source and controlled in volume to give a desired degree of reverberation.
A signal routed to an echo send line from a point after the input fader. The position on the echo send switch which accomplishes this. An after-the-signal tape echo, caused by print-through.
A signal routed to an echo send line from a point before the input fader. The position on the echo send switch which accomplishes this. A before-the-signal tape echo, caused by print-through.
The signal path and the associated controls that affect the signal returned from an artificial echo and/or reverberation system.
The signal path and the associated controls that affect the signal sent to an artificial echo and/or reverberation system.
The tape used to create artificial echoes in a tape delay system.
On a tape recorder, a switch that puts the machine in the play mode, while the take up motor remains disabled. Thus, the segment of tape being played spills off the machine, and may be easily discarded.
Process of cutting and splicing a magnetic tape to remove or rearrange certain segments. Producing a master tape by splicing together segments of several different takes.
The value of alternating or varying current that will produce the same amount of heat as the same value of direct current. Also called rms current.
The root mean square of the instantaneous sound pressure at one point over a complete cycle. The unit is the dyne per square centimeter.
Also called the rms (root mean square) value. A value of alternating current that will produce the same amount of heat in a resistance as the corresponding value of direct current.
The ratio (expressed as a percentage) of the output energy in the required form to the total input energy. In a speaker, the ratio of power applied to input terminals expressed as a percentage.
(German) Resonances set up in a room or enclosure at frequencies determined by the physical dimensions.
Non-conductor which has been given a permanent electrical charge: used in microphones and other transducers.
Pertaining to a device, as a speaker, that involves both electric current and sound-frequency pressures.
A device that receives excitation from an electric system and delivers its output to an acoustic system, or vice versa.
Coil of wire, possibly having a core of soft iron, which behaves as a magnet only while a current is passing through it.
Pertaining to a phenomenon that involves the interaction of electric and magnetic field energy.
Smallest charge of negative electricity that may exist by itself or as part of an atom.
Frequency dividing circuit using split amplifiers rather than passive circuits.
A type of speaker in which sound is produced by charged plates that are caused to move while one is changed from positive to negative polarity, resulting in forces of attraction or repulsion.
A speaker with a movable flat metal diaphragm and a nonmovable metal electrode capable of reproducing high audio frequencies. The diaphragm is driven by the varying high voltage that is applied to the plates.
A housing that is acoustically designed for a speaker or speakers. Also called a tone cabinet in electronic organ technology.
The application of some form of signal processing before recording, that will be removed via complementary processing (decoding) during playback.
The process of changing a signal from one form of energy to another, as in a loudspeaker, which converts electrical energy into acoustical energy.
A graph of energy vs. frequency for a typical voice, musical instrument, or program.
The delivery of power from a generator to a load.
Graphical representation of the changing amplitude of a complex wave.
A series of graphs of sensitivity (of the ear) vs, frequency at various loudness levels. Also known as the Fletcher-Munson curves.
The process of modifying the amplitude/frequency response in a recording and reproducing system to produce flat overall characteristics, minimize noise or give an artistic effect. Phonograph records are cut with low frequencies attenuated and high frequencies boosted. Playback equalization compensates for this, producing a flat frequency characteristic. Equalization may be used to improve the quality of speech and may even involve removal of certain frequencies.
The net frequency response of an audio system in which two or more sections of an equalizer are in use.
Equalization applied in the playback circuit of a tape recorder to produce a flat frequency response.
Equalization applied in the record circuit of a tape recorder.
The practice of tailoring the frequency response of a signal delivered to a speaker to correct for certain frequency response anomalies created by the room.
An elaborate form of tone control that provides numerous regions of amplitude variation within the audio-frequency range.
An equalizer containing active components, such as vacuum tubes or transistors.
An equalizer with a series of slide controls, arranged so as to give a graphic representation of the resulting frequency response.
An equalizer in which the frequency selector control is continuously variable over a wide range.
An equalizer containing only passive components, such as resistors, capacitors and inductors.
An equalizer that supplies a constant amount of boost or attenuation at all frequencies beyond the equalizer's turnover frequency.
A network designed to duplicate the operating parameters of some other network. For example, a resistivelcapacitive network may be used to simulate a microphone line, for testing purposes.
A mike in a completely silent room still generates some residual noise. This generated noise can be measured and is figured by taking a mike's sensitivity and relating it to the threshold value of hearing. A more common method is stating the signal-to-noise ratio.
The leadoff head in a tape recorder that erases previous recordings from the passing tape by generating a strong and random magnetic field.
A fixed frequency oscillator built into the tape recorder to supply erase current.
A voltage that is proportional to the difference between an actual and a desired condition (as in a servo motor system). The error signal brings the system back to the desired operating condition.
The total instantaneous pressure at a point in a medium containing sound waves, minus the static pressure when no sound waves are present. The unit is the dyne per square centimeter.
An audio amplifier designed to provide an output level that increases out of proportion to the input level. An expander does the opposite of a compressor; it expands signals above a set threshold. If sounds above a threshold are expanded, it is equivalent to attenuating those below it. It can thereby reduce noise or low-level background sounds and when so used is called a noise gate. By attenuating decaying sound, reverberation time can be reduced.
The use of an expander in a playback system to restore peaks that may have been compressed during recording. The peak expander may also be used to widen the dynamic range of programs that were not compressed earlier.
In an expander, the ratio of dB change in input level to dB change in output level.
An exponential curve follows the progress of natural unrestrained growth or decay.
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