About The Compressor Parameters - Lexicon LEXICON480LV4 Owner's Manual

Page One
DLY
Front Delay
Page Two
EXS
Expander Slope
The Compressor/Expander Program
Compressor is a stereo compressor program, with a
user interface similar to several mastering compres-
sors. The important thing to keep in mind as you use
this program is: It always has unity gain at high levels.
The compression is achieved by adding gain as the
input level decreases.
If you are accustomed to standard compressors, the
following may be helpful:
Many compressors currently available allow you to set
the threshold — the level above which the output level
will be decreased. The threshold in the 480L's com-
pressor defines the level below which the output level
is increased. Signal level that is above this threshold
setting remains at unity gain. This allows you to leave
peak values intact while increasing the overall program
loudness.
dBFS
-10 dB
O
u
t
-20 dB
p
Slope = 2:00 to 1
u
t
-30 dB
G
a
-40 dB
i
n
-50 dB
-60 dB
-50 dB -40 dB
Compressor with a 2:00=1 ratio, with threshold set at
-10dB.
SLP GAIN
Slope Maximum Gain
EXG EXT
Expander Gain Expander Thresh
Threshold = -10 dB
-30 dB -20 dB -10 dB
Input Gain
THR
Threshold Down
About the parameters
Page One
DEL (Delay)
DEL is a stereo delay line which allows the digital
detectors time to adapt to the incoming signal. With
Attack Time set to 30ms, input delays of 30ms or so are
desirable. Much longer attack times are possible, and
the delay can be set up to approximately 200ms. Delay
is not a problem in a mastering situation, or when time
alignment can be corrected. If delay through the com-
pressor is not tolerable, shorter attack times can be
used, but there will be some noise and distortion on
transients.
SLP (Slope or Compression Ratio)
SLP varies from 1:1 (no compression), up to 99.99:1
(high compression). With high compression, the output
level is constant as the input level decreases. At 2:1
compression the output level drops 3dB for every 6dB
drop in input level.
GAIN (Max Gain)
GAIN sets the maximum gain the compressor will
have. Typically this would be set between 6 and 12dB.
More than 15dB will bring up noise on a low level signal,
and noise pumping may be obvious. The maximum
dBFS
allowed is 24dB.
THR (Threshold Dn)
THR sets the level above which the compressor always
has unity gain. Note that the level detected by the
compressor circuitry is the average level; the 480L
input lights read the peak level. Therefore, if the peak
to average ratio of the music is 10dB, THR must be set
to -10dB or greater, or the average output level can
exceed 10dB — and the peak output will overload. This
means that THR must be set carefully. As THR is
lowered, the compressor maintains unity gain until the
input level drops lower. If you are listening to the output,
the gain will appear to decrease as this control is
raised. Typically, you want to set THR to get the
maximum gain possible without overload.
Bank 10: the Compressor Programs
ATC
Release Time Const
Attack Time Const
RTC
9-2