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Operating Manual - PROTEA SYSTEM II Digital Audio Products
Ratio (RAT) is the degree of attenuation to the signal above the limiter threshold point. As the ratio increases,
less signal is allowed to exceed the threshold. For example, with the ratio set at 10:1, a 10dB increase in input level
results in just a 1dB increase in output level. Thus a lower ratio is a more pleasant sounding effect, while a high ratio,
while accurately preventing signal increases, reduces the dynamic range to a point where the audio sounds unnatural.
Limiter Attack (ATT) and Release (REL) Time Controls display units in milliseconds (ms); however, the
actual units are ms per dB. For example, when the Release control is set at 100 ms, the limiter's attenuation will
release at the rate of 100 ms per dB, or viewed in another way, it would release 10dB over 1 second of time. The attack
and release time action was designed this way to achieve a more natural attack and release behavior of a constant rate
rather than time. It should be noted that fast attack and release times may distort the audio signal. This occurs in any
limiter because a fast attack or release action changes the gain rapidly which will by definition, distort the waveshape
of long wavelength (low frequency) signals. Therefore, it is recommended that longer attack and release times be used
for lower distortion.
10-segment meters on the LCD indicate amount of GAIN REDUCTION and OUTPUT LEVEL, including a
Peak LED on the output meter. As with EQ and all other audio functions, the limiter is enabled by the In/Out key.
5.3.3 HPF/LPF
The HIGHPASS and LOWPASS filters of-
fer precise frequency adjustment of two 24dB/oc-
tave filters, creating accurate visual representation
of the pass band. The frequency indicated for each
filter is the -3dB point. Use the four softkeys to
shift the frequency for each filter. To quickly shift
both filters "off" while in this menu, press the FLAT
key to the right of the display.
5.3.4 DELAY
The DELAY feature is used to time
align two or more loudspeaker sources so that
the acoustic energy created by different speakers
at different locations arrives simultaneously at
a given listening point. Adjustments are made
using Course, Medium, and Fine softkeys
displaying milliseconds, feet, and meters.
Maximum delay per channel is 1365ms. Quickly
reset Delay Time to zero by simultaneously
pressing the up and down "Course" keys.
5.3.5 METERING
Press the MORE key to access the sec-
ond menu screen. Meters display input and out-
put levels in dBu or VU, selectable in the
UserPrefs menu. 0 dBu = 0.775Vrms, and
+4 dBu = 0 VU. To maintain the highest signal
to noise ratio possible, each local channel's in-
put level should nominally be 0 dBu, or -4 VU,
allowing 20dB headroom before clipping. Each
of the four local channels also use a two-color
(green/red) LED to indicate signal present (-15
dBu) and clipping (+20dBu) for that channel.
More
Menu
Preset 01
dB Meters
UserPrefs
MIDI
Security
-9
-6
-3
0
+3
+6
+12
Pk
In
+9
-12
Out
-9
-6
-3
0
+3
+6
+12
Pk
In
+9
-12
Out
-9
-6
-3
0
+3
+6
+12
Pk
In
+9
-12
Out
-9
-6
-3
0
+3
+6
+12
Pk
In
+9
-12
Out
4
1
2
3
(VU)
1.2K800 1K 1.6K
2K
2.5K
More
Menu
630
Preset 01
EQ OUT
Cmp/Lim
OUT
HPF/LPF
IN
DELAY OUT
20 100 1K 10K 20K
HPF=99Hz LPF=10.0KHz
1.2K800 1K 1.6K
2K
2.5K
More
Menu
630
Preset 01
EQ OUT
Cmp/Lim
OUT
HPF/LPF
IN
DELAY OUT
DELAY TIME:
0.00 ms
0.00 ft
0.00 m
Fine
Medium
Course