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What are they? How do they work? Are they worth it?
First of all, we had better define what an automatic mixer
is. An automatic mixer is a mixer that senses what microphones
are being used and turns them on. Some units only allow one
microphone channel to be on at a time, others allow several
to be on at once. A few units allow one of the microphones to
have priority over the others--for example, in a court the judges
microphone would have priority so as he or she begins talking,
the other microphones are turned off while their microphone
would be on. Each channel or input on an automatic mixer has
at least two controls. One control is the gain, or volume level.
The other control is the threshold control. This control allows
you to set how loud the signal at the microphone needs to be
before the microphone is turned on. This control would be set
to turn on when someone is talking in front of the microphone,
but not when there's just some noise or rustling of papers nearby.
Other units include controls for making the channel a priority
channel or equalizer controls for simple control over the highs
and lows. How does an automatic mixer fit into a church sound
system? Many sound reinforcement system designers will design
a system for a small church that uses an automatic mixer for
all of the microphones. All the church has to do is turn the
system on. Some designers will use an automatic mixer for only
a few microphones in a system. For example, the pulpit mic,
a handheld mic, and a wireless lapel mic. This then goes into
a regular "manual" mixer. The "manual" mixer
is used for Sunday morning services and special services. However,
the automatic part of the system takes care of mid-week services,
weddings and funerals. Each installation method assumes all
the controls have been set correctly. Problems occur when a
child gets up to a microphone to read or sing. Their voice may
not be loud enough to trigger the microphone on. Another problem
is when the person speaking drops their voice and speaks softly.
The microphone turns off and no one can hear them speak! An
good automix system can be set up--but it requires plenty of
the correct equipment to make it work well. Automatic mixers
are really only good for speech, too--music can get cut off
if it has a drop in volume. The Final Vote The reason to use
an automatic mixer is so that the minimum number of microphones
is on at the same time. The fewer microphones that are on, the
less chance you have of having feedback. If the system and room
is designed right, getting enought gain before feedback won't
be a problem. This being true, several microphones can be on
at once without any trouble. If this is the case, a regular
"manual" mixer will work just fine and will give even
easier control over the system. Adjustments can be made as needed,
but the system still doesn't need an operator. This is a fine
solution, but a larger system (more than 6 or 8 channels) requires
an operator. One note of caution: If your sound system is not
set up to be unattended, don't ever walk away from the controls
if there are mics turned on. If feedback occurs, you won't be
there to stop it before it destroys your equipment and peoples
ears! |
