Mackie 1402-VLZ Pro Owner's Manual Glossary - Page 15

RFI Radio Frequency Interference. High frequency radiation that often results from sparking circuits. This can be manifested in a number of ways in audio systems, but is usually evident as a high-frequency buzz or hash sound. ROM Read only memory is a type of computer memory that cannot be written to, but only read from. RMS An acronym for root mean square, a conventional way to measure the effective average value of an audio signal or other AC voltage. Most AC voltmeters are calibrated to read RMS volts, though on many meters that calibration is accurate only if the waveform is sinusoidal. effects devices. Mackie mixers call it an Aux Send. shelving A term used to describe the shape of an equalizer's frequency response. A shelving equalizer's response begins to rise (or fall) at some frequency and continues to rise (or fall) until it reaches the shelf frequency, at which point the response curve flattens out and remains flat to the limits of audibility. If you were to graph the response, it would look like a shelf. Or more like a shelf than a hiking boot. See also peaking and dipping. signal-to-noise ratio (S/N) This is a specification that describes how much noise an audio component has compared to the signal. It is usually expressed in dB below a given output level. S Sa value A measure of the relative liveness of a room. A low Sa means a very live room, and a high Sa means a dead room. S = the total surface area of the room, and a = the average absorption coefficient of all the surfaces. slap, slapback A single-delay echo without any repeats. Also see echo. solo Italian for alone. In audio mixers, a solo circuit allows the engineer to listen to individual channels, buses or other circuits singly or in combination with other soloed signals. sampling frequency This is the rate at which an analog signal is sampled during the analog-to-digital conversion process. The sampling rate used for compact discs is 44.1 kHz, but professional recordings are often sampled at higher sample rates, such as 96 kHz or even 192 kHz (that's 192,000 samples per second!). sound reinforcement A system of amplifying acoustic and electronic sounds from a performance or speech so that a large audience can hear clearly. Or, in popular music, so that a large audience can be excited, stunned, or even partially deafened by the tremendous amplification. Means essentially the same thing as PA (Public Address). send A term used to describe the output of a secondary mix of the input signals, typically used for foldback monitors, headphone monitors or spaghetti That mess of wires and cables in the back of your rack and/or console. You really can tame this. 15