422
7
OperationChapter 5
The TARGET LEVEL control
When setting up the 422, this is generally the control that you should adjust first. The TARGET
LEVEL control does just what the name implies. It establishes the volume where you want it.
Technically, the control sets a threshold. Incoming signals that exceed this threshold are com-
pressed downward towards the threshold. Incoming signals below the threshold are expanded
(leveled) upward towards the threshold. The 422's output is a reduced dynamic range replica of its
input, centered around the target level. As you adjust the TARGET LEVEL control, it s very easy to
see and hear the results. A quick glance at the OUTPUT level VU meter will show you the exact
effects of increasing or decreasing TARGET LEVEL.
The D
ETECTOR control
The D
ETECTOR control increases or decreases the sensitivity of the 422 to low level audio signals
and noise. As you turn this control counterclockwise, the 422 reaches down and increases the gain
of low level audio and/or noise. The optimum setting of this control is entirely dependent upon the
nature of the audio that the 422 is processing. For example, if the audio source is relatively clean
and quiet (like a CD), the position of the DETECTOR may be noncritical. To greatly increase the
volume of the low level signals on the CD, try a full counterclockwise setting of the control (-45).
On the other hand, if you try the same extreme setting with a noisy cassette recording, you may not
find the results to be pleasing. If you re processing a very noisy source, then turn the detector
control clockwise towards the -20 setting until the desired sound is achieved.
If you re unsure of where to position the DETECTOR control, then start with it straight up in the
twelve o'clock position. Weve found this to be a good compromise for unpredictable audio
sources.
The RATIO control
The RATIO control is used to increase or decrease the degree of leveling. At high ratios, the
program density increase results in a more present or up front sound. At low ratios, the 422
performs subtle, yet effective, automatic gain riding. At a setting of 5:1 (maximum) the effect of
the 422 AGC/leveling process is very audible.
The optimum setting of this control is usually dictated by the particular type of material one is
processing, and the desired effect. For example, if the 422 is part of a foreground/background
music/paging system in a high ambient noise environment, a higher ratio will produce maximum
intelligibility. As part of a broadcast chain, where the process itself must be as subtle as possible, a
2.5:1 or lower ratio is advisable.
If you re unsure of where to position the ratio control, then we suggest you start in the twelve
o'clock position and make upward and downward adjustments from there as you listen and
evaluate the results.
The PEAK LIMIT control
The PEAK LIMIT control sets an absolute ceiling threshold level to which the maximum output level
is limited. The control is calibrated in VU (volume units). The PEAK LIMITER is useful in any
application where it is desired to prevent overload of subsequent system components. This may
include applications such as high volume music systems in clubs and theatres, or transmission line
applications such as AM/FM radio and television.
When the control is turned to its full clockwise rotation, the PEAK LIMITER is bypassed. As the
control is rotated counterclockwise, the threshold is moved lower and the resultant limiting can be
observed as a reduction in overall output level on the OUTPUT LED meter.
The optimum setting for the PEAK LIMIT control is most often correlated directly to requirements of
downstream system components. If you’re unsure of where to set the control, then you may want to
try this: observe the OUTPUT level display and note the average output level, then adjust the PEAK
LIMIT control 10-12dB above the average output level. Set this way, the peak limiter will provide
protection without over limiting the signal. The LIMIT LED should only come on occasionally. If it
stays on constantly then your are applying too much limiting and should turn the PEAK LIMIT control
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