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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.
10
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