Mackie SR244 / SR324 Owner's Manual - Page 46

Appendices echo Echo is the reflection of sound from a sur- face such as a wall or a floor. Reverberation and echo are terms which can be used interchangeably, but in audio parlance a distinction is usually made: echo is considered to be a distinct, recognizable repetition (or series of repetitions) of a word, note, phrase or sound, whereas reverberation is a diffuse, continuously smooth decay of sound. Echo and reverberation can be added in sound mixing by sending the original sound to an electronic (or electronic/ acoustic) system which mimics natural echoes, and then some. The added echo is returned to the blend through additional mixer inputs. Highly echoic rooms are called live; rooms with very little echo are called dead. A sound source without added echo is dry; one with reverb or echo added is wet. effects devices External signal processors used to add reverb, delay, spatial or psychoacoustic effects to an audio signal. An effects processor may be used as an insert processor on a particular input or subgroup, or it may be used via the aux send/return system. See also echo, reverb. EQ See equalization EQ curve A graph of the response of an equalizer, with frequency on the x (horizontal) axis and amplitude (level) on the y (vertical) axis. Equalizer types and effects are often named after the shape of the graphed response curve, such as peak, dip, shelf, notch, knee and so on. equalization Equalization (EQ) refers to purposefully changing the frequency response of a circuit, sometimes to correct for previous unequal response (hence the term, equalization), and more often to add or subtract level at certain frequencies for sound enhancement, to remove extraneous sounds, or to create completely new and different sounds. Bass and treble controls on your stereo are EQ; so are the units called parametrics and graphics and notch filters. [A lot of] how we refer to equalization has to do with what a graph of the frequency response would look like. A flat response (no EQ) is a straight line; a peak looks like a hill, a dip is a valley, a notch is a really skinny valley, and a shelf looks like a plateau (or a shelf). The slope is the grade of the hill on the graph. Graphic equalizers have enough frequency slider controls to form a graph of the EQ right on the front panel. Parametric EQs let you vary several EQ parameters at once. And a filter is simply a form of equalizer which allows certain frequencies through unmolested and other frequencies reduced or not at all. Aside from the volume control, EQs are probably the second most powerful controls on any mixer (no, the power switch doesn't count!). fader Another name for an audio level control. Today, the term refers to a straight-line slide fader rather than a rotary control. family of curves A composite graph, showing on one chart several examples of possible EQ curves for a given equalizer or equalizer section. filter A simple equalizer designed to remove certain ranges of frequencies. A low cut filter (also called a high pass filter) reduces or eliminates frequencies below its cutoff frequency. There are also high cut (low pass) filters, bandpass filters, which cut both high and low frequencies but leave a band of frequencies in the middle untouched, and notch filters, which remove a narrow band but leave the high and low frequencies alone. flanging A term for phasing. Before digital delay effects units, phasing could be accomplished by playing two tape machines in synchronization, then delaying one slightly by rubbing a finger on the reel flange. Get it? FOH An acronym for Front Of House. See house and main house speakers. frequency Frequency is the number of times an event repeats itself in a given period. Sound waves and the electrical signals which represent sound waves in an audio circuit have repetitive patterns which range from a frequency of about 20 repetitions per second to about 20,000 repetitions per second. Sound is the vibration or combination of vibrations in this range of 20 to 20,000 repetitions per second which gives us the sensation of pitch, harmonics, tone and overtones. Frequency is measured in units called Hertz (Hz). One Hertz is one repetition or cycle per second. fully balanced See balanced. 44