Many
groups may not need or want to be burdened with the duties of
operation. In that case the system will be designed as simple as
possible (set-and-forget or an automatic mixer) and one or two people
will be taught how to turn it on. The DS&C phone number will be
close by in case of emergency or malfunction.
Set-and-forget
systems usually have less than eight inputs. Beyond that the burden of
open microphone channels severely hinders amplification and feedback
(howl) stability. The most cost effective s-and-f system is the
integrated mixer / amplifier. An entire sound system could be set up
with one of these, a couple of microphones and a speaker. It is ideal
for a small church, chapel, social hall, school auditorium or a
multipurpose room.
The
big brother variation uses an automatic mixer. Auto mixers are very
sophistocated logic or even computer controlled devices that turn mics
on and off as they are used. They maintain stability and high
amplification levels by automatically limiting the number of open
microphones and compensating for the number of microphones that are in
use. I have designed systems such as this with as many as forty inputs
in large synagogues and churches. Auto mixers are often used in
"congress" type situations where there are a great many participants
who may speak.