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dbx 165A Manual de instruções
INTRODUCTION
The db
x
Model 165 is a professiona
l
single channel
compressor
/
l
imiter that features the new dbx Over Easy
compressio
n
curve. T he dbx
Over
Easy compression
curve permits
ex
tremely smooth
_
, almost inaudible com
-
pression due to the gradual change of compression ratio
around the threshold, instead of the customary sharp
threshold. This curve, plus
dbx
's true RMS
level
detector
coup led to a wide-range vo ltage control led amp
li
fier in
a feed-forward circuit, makes it possible to achieve larger
amounts of compression wi
t
hout adverse audib le side
effects.
Th
e
RMS
I
eve
I
detector is separate
I
y accessible,
allow ing
vari
ous signal cond it ioners - equalizers, filters,
delay
l
ines, etc.
-
to be inserted in either th
e
level
detector or signal pat
h
independently. This feat ure aids
in the compression of certa in difficu lt types of materia l,
as wel
l
as in the creation of special effects. In addit ion
to dbx's automatical ly variable attack and release time
circu itry (as on the Models 160, 161, 162, 163 and
164), a front
panel
switc
h
and contro ls prov ide for
manually adjustab le attack and release rates over a
very wide range.
The Mode
l
165 also
feat
ures stereo co upling for
.
two
165's (at the touch of a front panel button), LED
ind icators show ing whether the
signal
is at, above or
bel~w the
~
hreshold of compression, a 30 dB dynamic
range meter (indicating
i
nput, output and gain change
levels), and a rear
panel
zero VU calibration adjustment.
A h~rd -w
i
red bypass switch, also located on the front
J:!ane
l
, is convenient for checking the effect
of
the
compression, and assures fai lsafe flow of audio through
th
e
unit. The max imum input level is +24 dB (12.3 V
RMS) and max imum output level is +23 dBm. The
output amplifiers have a sourc
e
impedance of 4 7 ohms
and wil
l
drive input loads of 600 ohms or greater
impedance. Output gain is also adjustable over a very
wide range(
+
20
dB), so the Model 165 is compat
i
ble
with
vi
rtually all professiona
l
sound and creative audio
equi
pment.
Perhaps the most flexible and useful compressor
/
+ 20
+
15
1o+
10
"O
_J
+
5
UJ
>
UJ
_J
0
,-
::>
Cl.
-
5
,-
::>
O
-
10
-
15
4
:
1
20: 1
oo:
1
Ro
tat
i
on Point Th resho
l
d
-
15
-
10
-
5
0
+ 5 + 10
+
15
+
20
IN
PUT LE
VEL
(d B)
3A -
Con
ve
ntion al Co
mp
ressor/ Limiter
l
imiter ever offered, the db
x
Model 165 is well suited
t
o
a w ide range of applicat ions incl uding: tape record ing,
disc mastering, radio and
T
V production and broadcast,
I
ive co ncert sound reinfo rcement, and theatrica
l
production.
More About Separate
Level
Detector Access
Because
aux
iliary sound equipment can be used to
process the level detector signal
but
not the main audio
inpu
t
signal (or vice-versa), the 165 offers the user an
opportuni
t
y to create many unusua
l
effects. By co n-
necting it to additional signal processors, such as a
parametric equalizer, the Mode
l
165 can be converted
to a de-esser, a voca
l
stresser or a level-sensitive filter.
Certain musical or vocal elements in a program
can
be
suppressed without affecting othe rs. In addition to these
signal co nditioni ng functions
,
many creat ive special
effects are possible.
More About Over Easy Compre ssion
Convent ional compressor
/
lim iters have a sharp knee
at the thresho ld point (see Figure 3A). That is, whe
n
the
input signal is below the t hreshold, the gain remains
fixed ( 1: 1 ratio or no compression), but when the input
signal goes above the thresho ld, t he gain abruptly
decreases according to the compression ratio for wh ich
the unit is adjusted (several
fi
xed compression ratios are
shown in Figure 3A). This abrupt change in gain
in
a
conventional compressor
/
l imiter is of
t
en aud ible and
therefore undesirab le to
t
he user.
The db
x
Over Easy approach ut il izes a soft knee
at the thresho ld of compression (see Figure 3B). The
Over Easy compressor
/
limiter gradually
i
ncreases its
compression ratio from 1:
1
towards
t
he set comp
ression
rat io as the input signal rises through the thresho ld
region.
T
hus an age old dream can be realized ...
dynamic range restrict ion without audib le, abrupt
gai
n
changes. When properly operated, the Model 165 is a
highly effective compressor
/
limiter that you don't
hear working.
+
20
+
15
co
+
10
"O
_J
+
5
UJ
>
UJ
_J
0
,-
::>
Cl.
-
5
,-
::>
O
-
10
-
15
oo: 1
\
Thr esho
ld
-
15
-
10
-5
0
+
5
+
10 +1
5
+
20
INPUT LEVEL (dB
)
3
B -
Over Easy
Comp ressor/
L
imi
t
er
Fig.
3
- Over Easy
TM
Ver
sus Co
nve
ntional C
o
m pression
5