527E
11
Applications
The 527E Voice Processor was designed to make the same kind of specialized processing that’s
applied to voice-overs and vocal tracks in recording studios available for use in paging, public
address and sound reinforcement. Typical applications will include a range of installations from
stadiums to churches. For example, use the 527E on stadium announcement mics where extra vocal
processing is required to help overcome the inherent acoustic problems that hinder intelligibility in
large venues. Churches often have key mics needing extra processing, such as lapel or wireless
mics. Adding the 527E to a key mic prior to the automatic mixer in churches yields significant
control advantages.
The following discussions illustrate some of the more useful applications for the 527E. As a result
of its versatility, combinations of the applications described here will normally be used.
Microphones - Compressing, Limiting, Expanding
The 527E’s dynamic range processor is used to control both over-modulation and noise. Noise, in
this case, may be electrically induced (hum, buzz, etc.), or acoustically transferred (paper rattling,
air conditioning, etc.), since the downward expander attenuates all below-threshold signals without
regard to origin. Careful adjustment of the two threshold controls allows the operator to put the
527E to work on any portion of the dynamic range. The expand threshold control governs the
527E’s activity in the lower part of the dynamic range, while the comp threshold governs activity in
the upper part of the range.
For smooth overall dynamic range processing that will tend to “homogenize” the sound and
remove only very low level noises, use a gentle compression ratio with a relatively high comp
threshold, and a relatively low expand threshold.
The soft-knee transition characteristic of the interactive processor allows the use of much higher
compressor/limiter ratios with much lower thresholds. The expander’s rapid rise below its thresh-
old, combined with the compressor’s smooth transition through its threshold, makes processing go
unnoticed. Use this application to “tighten up” voice signals. The expander eliminates noise and
adds “punch.”
Use the expander to remove background noise whether or not the compressor is being used. Be
sure the expander threshold is set low enough to allow even the lowest level speech sounds to
pass. If set correctly, the threshold will attenuate whenever a mic is not in use, eliminating extrane-
ous pickup of stage sounds and reducing feedback. To remove the compressor, set the compres-
sion ratio to 1 (essentially out of the circuit).
Likewise, the compressor/limiter may be used without the expander to control only the upper end of
the dynamic range. For general purpose overall gain control, use compression. Set the ratio
between 2:1 and 3:1, with a comp threshold setting that results in 6dB to 10dB attenuation.
Limiting is used for very definite control of the maximum level. As the name implies, limiting sets
the upper limit, but is not intended for general purpose overall gain control. For limiting, set the
ratio at 10:1, with the comp threshold control set to provide no more than 3dB to 6dB attenuation.
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
generally sound good enough to be used for more than 6dB attenuation.
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.
Chapter 7
Содержание 527E
Страница 1: ...527E Voice Processor User s Guide 527E...