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Operating Manual - PROTEA SYSTEM II 4.24C Crossover / System Processor
10
4.6e Limit
A full function compressor/
limiter is included on each output
channel. A limiter is commonly used
to prevent transient audio signal spikes
from damaging loudspeakers, manage
analog and digital recording levels,
optimize broadcast levels, or "thicken"
the sound of an audio source (com-
pression). The adjustable parameters
include Limiter In/Out, Limiter
Threshold, Ratio, Attack Time, and
Release Time.
The 4.24C limiter threshold range is from -20dBu to +20dBu. This setting determines the signal level above
which gain reduction begins, and is indicated by the yellow LED (Lim) in the output meter section. Increases in audio
level above the threshold will be reduced according to the ratio settings.
The ratio control determines the amount of gain reduction above limiter threshold. Ratio ranges from a gentle
1.2:1 to a brick-wall INF:1. To illustrate how the ratio control works, imagine a commonly used loudspeaker protec-
tion ratio of 10:1, which means that for every input signal increase of 10 dB above threshold, the output level will only
increase by 1dB. The higher the ratio, the more pronounced the audio effect, so use the lowest ratio possible to
sufficiently address the problem.
Attack (A__ms) and Release (R__ms) settings adjust the time it takes the limiter to engage and then disengage
when the signal increases above threshold and then subsequently falls back below threshold. Attack time is adjustable
from 0.5ms through 50ms, while release time ranges from 10ms through 1s. A very fast attack time can sound unnatu-
ral, while a very long attack time can miss some of the initial transient. Similarly, a very short release time can make
the audio sound uneven, while a very long release time can create "pumping", or "breathing" characteristics depending
on the kind of signal. Experiment to find the best solution for a given application.
4.7 Other Functions
The Protea 4.24C has a full complement of non-audio functions within a single
keystroke to navigate around the product quickly. Recall, Save, Copy, Mute, and a Utilities
menu complete the user friendly interface Protea products are known for.
4.7a Recall
There are 30 stored presets which can be recalled on the 4.24C. Note: A preset
recall will overwrite the working settings, so make sure the current configuration is saved
before continuing or it will be lost. Remember, an unsaved working preset shows (modi-
fied) on the preset name screen. Press Esc to see the preset name screen. The 4.24C
always loads the working preset on power-up, so as to preserve any changes should the
power be inadvertently turned off prior to saving.
Ashly has included ten preset templates as starting points for common 4.24C configurations, and these preset
templates repeat as they scroll through the 30 presets. To recall a new preset, press the recall button once, select the
desired preset number, and press recall again. At this point the LCD display prompts the user to mute the outputs or
not, and selecting Yes or No will load the new preset and mute all outputs if so desired. A new preset may have
dramatically different settings capable of damaging sound system components, so be careful not to recall the wrong
preset while the system is on. To be safe, always select "Yes" to mute all outputs.
1
2
Save
Cop
y
Mute
Recall
Util
Limiter
Channel 1-8
Limiter
Ratio
Limiter LCD Displa
y
-20 to +20
Release
Time (ms)
Threshold
Attack
Time (ms)
LIMITER 1
INF:1 A05ms
0dBu
R100ms