Microphones - Shure MUSIC EDUCATORS Manual

Signal processors are devices, usually connected between the mixer and power
amplifier, used to enhance the signal or fix problems with the sound. The most
common types of processors are equalizers, effects processors, and compressors.
An equalizer is basically an extremely selective set of tone controls that allow you to
boost or cut specific frequencies. Typical applications for equalizers are tone shaping
and feedback control (see sidebar on feedback - page 19). Effects processors are
used to create special sound effects, such as reverb (sounds like a big, reverberant
room) and delay (echo), among others. Compressors control varying signal levels.
A loud signal that passes above the compressor's threshold is reduced (or com-
pressed) by a given amount. A compressor can also help prevent distortion or
damage to the loudspeakers. Of the processors listed above, the equalizer is the most
useful in just about any sound reinforcement application.

Microphones

Many of the same microphone rules used in recording apply equally as well for live
sound reinforcement. If you skipped the recording chapter, please back up and read the
section on microphones – the laws of physics don't change for sound reinforcement.
A major difference between microphone placement in live sound versus recording
is proximity to the sound source. The goal in sound reinforcement is to get the
microphone as close as possible to the sound source, for two reasons:
• Primarily, placing all microphones as close as possible achieves maximum
sound level before feedback occurs.
• Secondly, close-miking reduces leakage and pickup of unwanted sounds.
Other general recommendations for live sound microphone techniques include:
• Try to get the sound source (instrument, voice, or amplifier) to sound good
acoustically before attempting to put a microphone on it.
• Use as few microphones as necessary. The more microphones you use, the
more likely you are to have feedback problems. Using fewer microphones will
allow more volume before feedback occurs.
• When multiple microphones are used, the distance between microphones
should be three times the distance from
each microphone to its intended sound
source. This prevents comb filtering, an
unpleasant, hollow sound created when
two or more microphones pick up the
same sound source. This technique is
known as the 3-to-1 Rule (see figure 8).
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Figure 8: 3-to-1 rule