Symetrix 258E, Руководство пользователя, Страница: 31 / 46

528E
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Bear in mind that limiting is an extreme dynamic control action intended to prevent overload
farther down the line. Limiting may be more pleasing to the ear than clipping distortion, but it
doesn’t sound good enough to be used for more than 6dB attenuation.
Using the De-esser
De-essers are used to reduce the level of certain high frequency vocal sounds like sibilance,
overemphasized fricatives, and lip smacking. The 528E’s de-esser provides control over much
lower frequencies than would normally be considered “essing.” The additional control range
greatly enhances the versatility of the de-esser.
Cleaning Up News Feeds
Use the de-esser to reduce unnatural high frequencies, the compressor/limiter to prevent overload,
the expander to eliminate noise, and the parametric to make the feed sound better and/or get rid of
interference (hiss, noise, extraneous sound, etc.).
Actualities carts
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that are prepared with the 528E produce an end product with better intelligibility
and improved signal to noise ratio. The object of the processing is to keep dynamic range within
the real limits of the recording equipment, to eliminate extraneous noise, and to get better sound.
Increasing Gain Before Feedback
To optimize a PA system’s response for minimum feedback, tune out the feedback using the
parametric equalizer. To find and eliminate resonances that can become feedback problems, turn
the system on, with the microphone(s) and speaker(s) in place as they will normally be used, then
follow the sequence below. Gain before feedback should increase about 6dB (perhaps as much as
15dB) with this technique.
1. Note the settings of each of the compressor controls.
2. Temporarily set the compressor ratio to 10:1. Increase system gain very carefully until a
feedback frequency becomes slightly audible.
3. With the bandwidth set at about .3 octave, and the cut/boost control set for about -15dB, tune
the frequency control of one section until the feedback is no longer audible.
4. Increase system gain until feedback becomes slightly audible again.
A. If it’s the same frequency that was heard first, readjust the same frequency and bandwidth
controls until it again subsides.
B. If it’s a new frequency, repeat Step 2 using another of the EQ sections.
5. Increase gain again to find the third most prominent feedback frequency. Repeat Step 2 using
yet another of the EQ sections.
6. Reduce system gain to normal operating levels.
Parametric EQ in the Sidechain
The parametric equalizer can be placed in the sidechain of the dynamic range processor to make
compression, limiting, or expanding action frequency sensitive. The equalizer is patched into the
sidechain, so the audio signal that will ultimately become the VCA’s control voltage can be
equalized before being fed to the detector circuitry (see Chapter 6 for additional information and
Chapter 7 for hookup details).
To make the 528E’s compressor/limiter more sensitive to high frequencies, boost the high frequen-
cies on the equalizer. This increases the sensitivity of the compressor’s control circuits to those
particular frequencies, so the compressor/limiter responds more to those frequencies than any
others (in effect, the threshold setting is lowered by the extent that the high frequencies have been
boosted). Juggling the relationship between the amount of boost and the threshold setting can have
the effect of only compressing when the signal contains significant energy in the region boosted by