BSS Audio OPAL Series DPR-522 Owner's Manual - Manual (Page 29)

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Drop-in A term used to describe the way in which new equipment, or a hitherto
unused function of equipment already connected, can be switched into a live
sound system without causing unwanted effects, i.e: without causing clicks or
a noticable change in sound level.
Duck The term given to a unit that attenuates the program when another signal
exceeds a threshold level. This is approximately the opposite of what a gate
does.
Equalisation Modification of the frequency response of an audio system, regardless of
level, for corrective or enhancement purposes.
Frequency The repetition of a waveform. The unit of frequency is Hz, and 1 cycle per
second is equal to 1Hz. The audio band is generally restricted to frequencies
of 20Hz to 20,000Hz (20kHz).
Frequency Response The equipment’s relative gain compared to frequency. Generally expressed
as +/- a certain number of dBs from 20Hz to 20kHz.
Headroom The amount, in dBs, above the normal operating level that can be used before
serious distortion commences.
Hold The time that the gate pauses after the ATTACK phase, before commencing
the RELEASE phase.
Impedance The AC equivalent of resistance and measured in ohms. It indicates the
amount of drive required for an input, or the drive capability of an output, at a
given signal level.
Key The signal that is processed to produce the gate trigger. This may or may not
be the same as the main program.
Level The amplitude of a signal, measured in Volts or Decibels.
Line Level Generally indicates a signal whose level is between -10 and +10dBu or -14
to +6 dBV. Mic level refers to levels around -40dBu.
Octave A logarithmic unit for expressing frequency ratios. Positive values indicate an
increase and negative ones a decrease. One octave ‘up’ the scale is
equivalent to double the frequency. One octave ‘down’ is equivalent to half
the frequency.
Release Time The time required for a compressor or limiter to restore its gain to normal, after
the input signal has fallen below threshold.
Threshold The pre-settable level above which a compressor or limiter will commence to
gain reduce.
Transient A sudden burst of energy in an audio signal which only lasts for a small period
of time relative to the rest of the signal. The level of these transients can often
reach 10 times (+20dB) or so above the normal operating level of the audio
equipment, and may cause distortion of headroom is inadequate.
Side chain The part of the circuit responsible for producing the gate trigger signal. See
also 'Key'.