Ashly FET-200 - Page 11

dBm
unit of measurement in decibels wnere 0 dBm = a power level of 1
into a 600 ohm load. Originally defined by the telephone
company to measure line levels.
dBV
Decibel Volts, an update of the dBm definition where 0 dBV = tiie same
voltage level as 0 dBm, but with no regard to power or impedance. 0 d3V =
0.775 Volts. This unit is much more appropriate for modern audio
equipment with high impedance inputs and low impedance outputs.
DISTORTION
Generally refers to ANY modification of an audio signal which produces
new frequencies which were not in the original. Examples are harmonic
distortion, where a circuit adds overtones to a fundamental signal, and
intermodulation or IM distortion, where two frequencies beat together to
produce sum and difference frequencies.
EQUALIZATION
Modification of the frequency response of an audio system for either
corrective or enhancement purposes.
FEEDBACK
Generally refers to any process wiiere an output is in some form routed
back, to an input to establish a loop.. Negative feedback tends to be be
seif stabilizing, while positive feedback causes instability.
FILTER
A circuit designed to pass some frequencies, but not others. There are
three general categories of filters: High-pass, band-pass, and low-pass.
The high-pass filter passes frequencies above a certain limit, the low-
pass passes frequencies below a limit, and the band—pass passes one group
of frequencies without passing those above or below. Our equalizer uses
band-pass filters, crossovers use high and low-pass filters.
FREQUENCY
The repetition race of a waveform. Frequency is measured in Hertz. One
cycle per second (cps) is one Hertz (Hz). The higher a note on a musical
scale, the higher its frequency.
FREQUENCY RESPONSE
Refers to relative gain and loss at various frequencies across the audio
band. May be illustrated by a graph called a frequency response plot,
usually graphing decibels vs. Hertz or octaves.
HERTZ (Hz)
The unit of frequency measurement. (Formerly called Cycles-per-Becond:
this explains it perfectly)
HEADROOM
Refers to the increase in level above normal operating level that can be
obtained without clipping. Usually expressed in dB.
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