Lesson Description
Auto Mixer Part 1
5m 9s
In this video, we describe the pitfalls of mixing a number of open microphones for speech applications and how to use the auto mixer to improve your overall sound and help reduce feedback.
Video Transcript
Auto Mixer Part 1
5m 9s
0:07
Hi! Today we’re going to be talking about the Auto mix feature
0:11
Auto mix is most commonly used for speech applications such as conferences or presentations.
0:16
Or something Like…a panel discussion at a comic book convention! Not that I'm into that or anything…
0:22
It's any situation in which there are multiple talkers and mutiple microhpones
0:26
Don’t be confused by the term “Auto mixer”. This does not mean that the TouchMix will now
0:30
automatically mix your band for you while you stand by and watch.
0:36
An auto mixer is used to balance a number of open microphone channels.
0:39
One of the great things about the Automatic Mixer is that it’s …well…pretty much automatic and
0:43
simple to operate. You select the channels you want to include in the auto mix. Then toggle the auto
0:49
mixer function on. And that’s it! The mixer does the rest. Before we show you that, let’s talk about
0:54
when you should use it.
0:55
First, it’s important to mention that the auto mixer on the TouchMix is a gain sharing
0:59
automatic mixer. In the general context of sound mixing, there are two different approaches to auto
1:04
mixing. Gain sharing auto mixing and gating auto mixing. Gating auto mixers will gate mic channels on
1:09
and off completely. But that’s not what the TouchMix does. The TouchMix uses gain sharing auto
1:14
mixing which controls a group of live microphones, turning up mics when someone is talking, and
1:18
turning down mics that aren’t being used.
1:21
In the example of comic book convention hall, we might have 3 or 4 panelist plus a
1:25
moderator, all with individual microphones. There might even be an additional
1:29
microphone in the audience for people to ask questions. That’s 6 open microphone channels.
1:33
All of these microphones need to be open throughout the event because all of our panelist
1:38
need the ability to talk freely during the discussion. And of course we want all of them to
1:42
be heard clearly at any point within the discussion.
1:45
But, if you have one channel open at maximum gain, opening another might create an
1:49
additive effect that causes the system to feedback.
1:52
Let’s consider, for example, the noise of a few hundred people in our convention hall or
1:57
mic bleed from one panelist’s speech being picked up by the neighboring microphones. In
2:01
either case, you’re going to have a high level of background noise to contend with. In a
2:05
high energy event like this you’ll also be contending with sudden peaks in noise from
2:09
crowd reactions such as laughter or applause.
2:16
A building like this is probably going to have an air handling system for climate control.
2:20
These units are often quite noisy and will add further to the background noise, if picked
2:24
up by the microphones.
2:26
One Microphone picking up the air conditioning isn’t a big deal. But when all the mics are
2:30
on air conditioning or crowd noise is added together according to the number of mics
2:34
being used and now it becomes a problem!
2:37
The mix engineer could very well ride all 6 faders for the duration of the show, turning up
2:42
talkers as they talk and down when they don’t. However, without being able to anticipate
2:47
with perfect accuracy which participant will speak next in spontaneous discussion, you
2:52
might end up with certain words being absent when a talker begins to talk, because the
2:56
operator does not respond quickly enough to “fade up” a microphone channel. Sudden
3:00
interjections by panelists may even be lost completely.
3:03
The auto mixer not only frees up the mix engineer from having to constantly ride multiple
3:07
faders, it also mixes the channels with much greater accuracy. Let’s apply our auto mixer
3:13
and listen to what it does.
3:15
To access the auto mixer press “Menu” and then “Auto Mixer” on the screen. This will
3:20
bring up the auto mixer.
3:22
Each channel has two meters. The green meter on the left is the normal input level for
3:26
the channel. The blue meter displays the amount of gain that the auto mixer is applying
3:30
to the channel.
3:31
Now, you can choose which microphone channels you want to include in the auto mix.
3:36
You can also place channels in one of two auto mix groups.
3:40
From there, simply toggle the auto mixer “In” using one of the two toggle switches. And
3:44
the mixer does the rest. It’s that easy!
3:47
The Auto mixer is going to actively compare the signal levels of any assigned channels
3:51
and apply an algorithm that determines which talker or talkers are currently speaking.
3:56
The auto mixer then sends a control command to the channels that allocates more gain to
4:00
the channels with an active talker and less to the channels with an inactive talker. With
4:04
each microphone automatically turned down when a talker is not talking, feedback and
4:08
extraneous noise are reduced.
4:11
All of the extraneous noise is significantly reduced in the mix to allow for each panelist to
4:15
be heard clearly. With the background noise removed, and gain reduced on unused
4:18
channels, the system is also much less susceptible to feedback.
4:22
The Auto Mixer does this while maintaining a natural ambiance from the room. Behind the
4:26
scenes, the auto mixer is making rapid and sometimes dramatic changes in the gains of
4:30
the input channels while giving off the illusion that nothing is happening at all
4:34
If you’re using the auto mixer a lot, it’s handy to have a user button assigned to take you
4:38
there. Here’s how to set that up.
4:41
Go to Menu. Then User Buttons and select a User Button from the top. In the three
4:46
windows select “Go To Screen” then “other” then “Auto Mix”. Touch “Assign” and you’re done.
4:56
At this time, let’s take a quick break. Come back whenever you’re ready for the next video.