Control elements, Frontliner, Compressor/limiter – SPL Frontliner Modular Recording Channel User Manual
Page 19: Threshold, Ratio, Attack, Thr eshold, On auto
19
Frontliner
ON
The On button activates the compressor/limiter module. Set the VU/GR switch to GR (=gain
reduction) to see the processing intensity (for further information read ”MAKE UP” on page
20).
Usually the signal flow follows the design of the Frontliner, so the input signal normally comes
from the de-esser. However, with the EQ PRE COMP. switch the compressor/limiter module
can be switched behind the equalizer. This allows the compressor to be used as a final
compressor or limiter after the equalizer (see „EQ PRE COMP” on page 15).
THRESHOLD
The THRESHOLD control determines the compressor threshold value, thus from which level
the compressor starts working. The value scale for the THRESHOLD control indicates the level
in dBu and ranges from 21 dB (fully left) to -58 dB (fully right). Turning the control to the right
intensifies processing: fully left provides no compression, and fully right provides compres-
sion starting at a level of approximately -58 dBu.
RATIO
The RATIO control is used to set the ratio between the original signal and the compressed
signal. A ratio of 1:5 (RATIO control set to 5.0) means that a level increase of 5 dB on the input
results in an output level change of 1 dB. The more the control is turned right, the more ‘dense’
the sound becomes. The compressor works as a limiter when RATIO is turned fully right to
infinity.
ATTACK
The ATTACK control determines how fast the compressor reacts. When turned fully left this
time is 0.1 milliseconds, and turned fully right the time is approximately 1000 milliseconds
(one second). Sudden, fast and impulsive attacks are called transients, they are produced for
example by hitting a drum. We identify natural sounds by transients, so they are enormously
important for sound impressions.
With very short ATTACK times the compressor reacts to every level jump and all transients are
processed. With slower settings, transients become more and more audible – a drum kit for
example can achieve more presence in a mix and sound faster with such settings. The best
ATTACK settings are not always easy to find, since you usually need to find a compromise.
Very fast settings run the risk of producing audible distortions – especially in the case of low
frequencies, since the compressor now tries to catch each waveform rise. The corresponding
control signal assumes a “saw-tooth” form which distorts the audio signal. To suppress this
effect, you would have to again increase the attack time until distortion no longer occurs – but
without missing the aim of processing.
The Frontliner offers a switchable automation feature for the ATTACK and RELEASE param-
eters to achieve perfect results when you are not satisfied with fix settings (see next page).
Compressor/Limiter
Control Elements
7 5
3
1 0
3
5
30
50
70
100
VU
5
3
1
VU
20
10
0
%
MIC GAIN
S-R
EDUCTION
IN
STR
UMEN
T
S-
DETECT
AD
-OVL
13
1
4
1
5
1
6
1
8
20
2
2 24
26 28 30
33
3
6 3
9 4
2 4
5 5
2 6
1 68
INS
TR. GAIN
LINE GAIN
RATIO
ATTACK
LMF
MHF
LMF – / +
MHF – / +
AIR BAND
TU
BE
SATURATIO
N
INSTR.
LINE IN
TUBE
+15
dB
ON
ON
MUTE
EQ PRE
COMP.
EQ/TUBE
COMP.
EXTERNAL INPUTS
DE-ES.
AUTO
48 V
PAD
R e c o r d i n g C h a n n e l
Ø
MAKE-UP
RELEASE
OUTPUT
Sound Performance Lab
Made in Germany
ON
0
-1
-2
-3 -4
-6
-
9
-1
1
-1
2
21
16
11
6
0
-5
-9
-
16
-22 -30
-38
-4
6
-
54
-58
1.2
1
.4
1
.7
2
.0
2.3
2.7 3.0
3
.6
5.0
1
6
∞
0
1
0
2
0
3
0
4
0
50 60
7
0
80
9
0
10
0
-20
-
13
-
7.
5
-4
.5
-
2
0
1.5
3
4
5
5.
5
0.1
0.2
0
.4
1.0
2.5
7.0 16
4
0
1
30
5
30
1
000
0.03
0
.05
0.
09
0
.15
0.
25
0.4 0.65
1
.0
1.3
1
.8
2
.0
0
0
.5
1
2
3
4
5
6
7 8
9
10
1
2 1
4
16
1
9
2
0
-12
-
10
-
5
-2
.5
0
2.5
5
7.5
10
12
-12
-
10
-
5
-2
.5
0
2.5
5
7.5
10
12
-10
-8
-6
-
4
-2
0
2
4
6
8
10
680
8
20
1
k
0
1
k
5
2
k
7
3
k
4 4
k
5
6
k
5
1
0
k
13
k
15
k
30
4
0
5
0
80
125
160 200
3
00
5
00
64
0
70
0
Model 2800
GR
VU
VU
PPM
0
dB
-10
dB
THR
ESHOLD
Frontliner
6
8
1
1
1
4
1
7
1
9
2
1
23
25 26 27 29 3
2 3
5 3
7 3
9 4
1 4
2
4
3
-20
-1
8
-
12
-9
0
3
9
10
dB
1:x
dB
dB
dB
dB
Hz
Hz
%
ms
s
dB
dB
dB
ON
AUTO
ATTACK
0.1
0.2
0
.4
1.0
2.5
7.0 16
4
0
1
30
5
30
1
000
ms
21
16
11
6
0
-5
-9
-
16
-22 -30
-38
-4
6
-
54
-58
THR
ESHOLD
dB
RATIO
1.2
1
.4
1
.7
2
.0
2.3
2.7 3.0
3
.6
5.0
1
6
∞
1:x