Mackie 1402-VLZ Pro Owner's Manual Glossary - Page 8

FOH An acronym for Front Of House. See house and main house speakers. Nobody involved with audio ever goes to the Back of House because they never have time to drink enough beer. frequency The number of times an event repeats itself in a given period of time. Generally the time period for audio frequencies is one second, and frequency is measured in cycles per second, abbreviated Hz, honoring the physicist Dr. Heinrich Hertz (who did not invent the rental car). One Hz is one cycle per second. One kHz (kilohertz) is 1000 cycles per second. The audio frequency range is generally considered to be 20 Hz to 20, 000 Hz. This covers the fundamental pitch and most overtones of musical instruments. G gain The measure of how much a circuit amplifies a signal. Gain may be stated as a ratio of input to output voltage, current or power, such as a voltage gain of 4, or a power gain of 1.5, or it can be expressed in decibels, such as a line amplifier with a gain of 10 dB. gain stage An amplification point in a signal path, either within a system or a single device. Overall system gain is distributed between the various gain stages. hold, and release time are some of the adjustable gate parameters. graphic EQ A graphic equalizer uses slide pots for its boost/ cut controls, with its operating frequencies evenly spaced through the audio spectrum. In a perfect world, a line drawn through the centers of the control shafts would form a graph of the frequency response curve. Or, the positions of the slide pots give a graphic representation of boost or cut levels across the frequency spectrum. Get it? ground Also called earth. Ground is defined as the point of zero voltage in a circuit or system, the reference point from which all other voltages are measured. In electrical power systems, ground connections are used for safety purposes, to keep equipment chassis and controls at zero voltage and to provide a safe path for errant currents. This is called a safety ground. Maintaining a good safety ground is essential to prevent electrical shock. Follow manufacturer's suggestions and good electrical practices to ensure a safely grounded system. Never remove or disable the grounding pin on the power cord. In sensitive electronic equipment, tiny currents and voltages riding on the ground (so it's not truly zero volts) can cause noise in the circuits and hamper operation. Often a ground separate from the power ground is used as the reference point for the electronics, isolating the sensitive electronics from the dirty power ground. This is called a technical ground. Quality audio equipment is designed to maintain a good technical ground and also operate safely with a good safety ground. gate A dynamics processor that automatically turns off an input signal when it drops below a certain level. This can reduce the overall noise level of your mix by turning off inputs when they are not in use. Threshold, attack time, ground loop A ground loop occurs when the technical ground within an audio system is connected to the safety ground at more than one place. This forms a loop around which unwanted current can, and does flow, causing noise in the audio 8