Ashly Electronic Amplifier none User Manual
Page 33
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DEFINITION OF TERMS AS USED IN THIS MANUAL
ACTIVE
Electronic circuits which use devices such as transistors and integrated
circuits, and which are capable of voltage and power gain as well as
loss.
Circuits
using
only
resistors,
capacitors,
transformers,
etc.,
are
referred to as passive.
AMPLITUDE
The voltage level of a signal. May be measured in volts or decibels.
Generally corresponds to the volume or intensity of an audio signal.
BALANCED
A 3-wire circuit arrangement in which two conductors are designated as
signal lines (+ and -), and the third is a shield and chassis ground. The
signal lines are of opposite polarity at any given moment, and are of
equal
potential
with
respect
to
ground.
Balanced
input
amplifiers
are
used on all Ashly SC series products to improve hum and noise rejection.
Jumpering signal minus (-) to ground provides an unbalanced input.
BUTTERWORTH
The
name
of
a
particular
filter
response
shape.
The
response
is
essentially
"flat"
within
the
pass-band,
is
3dB
down
at
the
cutoff
frequency, and continues to attenuate at a constant slope. Also called a
"maximally
flat"
or "critically
damped"
filter
shape,
it
is
very
popular
for crossovers and shelving filters.
CENTER FREQUENCY
The
frequency
(or
pitch)
at
which
a
filter
is
most
effective.
In
a
parametric
equalizer,
it
refers
to
the
frequency
where
a
particular
boost/cut control has maximum effect.
DAMPING
A force which opposes the tendency of a system to oscillate.
dB
dBm
A
unit
by
which
audio
levels
can
be
COMPARED.
Often
thoroughly
misunderstood are the concepts that decibels represent the level of a
signal compared to some reference level (15 dB cut means a certain level
less than a previous level — the absolute level of the signal need not
be known), and that decibels are a logarithmic unit.
Some handy numbers to remember when dealing with decibels;
+3 dB = Double Power
+6 dB = Double Amplitude, Quadruple Power
+ 10 dB = lOX Power
+20 dB = lOX Amplitude, lOOX Power
A unit of measurement in decibels where 0 dBm = a power level of 1
milliwatt
into
a
600
ohm
load.
Originally
defined
by
the
telephone
company to measure line levels.
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