Gating Automatic Mic Mixer
| Site: | QSC |
| Course: | Q-SYS Level 1 Training |
| Book: | Gating Automatic Mic Mixer |
| Printed by: | Guest user |
| Date: | Thursday, 21 November 2024, 7:13 AM |
Description
Video Transcript
0:08
Alright, let’s swap from the Gain-Sharing Automatic Mixer to the Gating Automatic Mic Mixer.
0:14
You’ll find it back in the Schematic Library under Audio Components and Mixers.
0:18
You’ll notice that mine is listed as BETA, because this is a newly-renovated component in Designer version 4.2.
0:25
If you’re using a newer version of the software it won’t say BETA,
0:29
but it should operate in the same ways. The main goal of the Gating Automatic Mic Mixer is to open
0:35
or close its incoming channels based on whether or not they reach a certain threshold.
0:40
Basically, if someone is speaking into a microphone a channel should gate open,
0:44
and if not then the channel should gate closed. Its properties are similar to the Gain-Sharing Automixer
0:51
I’m going to change its channel count to 4, I have the option to use a Mix Only output,
0:56
direct Channel outputs, or both, and I can activate the Side-Chain Filter
1:01
that fine-tunes the type of audio that the Mixer listens for on each channel.
1:05
I’m going to connect this to my design, but I actually can’t use the same
1:08
pink-noise generators I used in the last video.
1:11
You see, one of the benefits of the Gating Automatic Mic Mixer is its Noise Floor Tracking.
1:16
This mixer tracks the steady or slowly-changing background noise of a room such as air conditioning,
1:23
and adjusts the threshold required for each channel to open relative to this slowly changing noise floor.
1:30
Without this, a noisy air conditioner might open every microphone channel,
1:35
or when the air conditioning turns off a person might have to speak louder
1:40
in order to still reach the open threshold. Noise Floor Tracking takes care of all of this. But for my example,
1:47
I can’t use those pink-noise generators anymore because the Mixer will think
1:51
that the steady pink noise is background noise, and nothing will work.
1:55
So instead I’ve changed John, Paul, George and Ringo into
2:00
Audio Players that are looping some prerecorded vocal tracks:
2:03
"Hello, I’m John."
2:09
"Hello, I’m Ringo."
2:12
Let’s double-click the Mixer to look at its Control Panel,
2:15
and let’s take a look at each section from left to right. First we have the Side-Chain Filter,
2:20
which we activated in the properties panel, and we can adjust what aspect of each channel
2:25
is being analyzed to determine if it reaches its open threshold.
2:29
By default a High-Pass filter is active since we’re generally listening for human voices,
2:34
but you could change this however you like.
2:36
Remember, this is not applying a high-pass filter to the channels,
2:40
it only selects what audio spectrum is being analyzed, without actually affecting the channel at all.
2:47
Next is the Gate section, which determines how the channels are opened.
2:51
The most important knob here is the "Threshold Level Above Noise" knob.
2:57
This is how loud a channel must be – above the Noise Floor – in order for it to be gated open.
3:02
If it does not reach this threshold, then it is attenuated by the amount of the Depth knob,
3:08
to keep those closed channels silent.
3:11
The Hold Time determines how long a channel will remain open
3:14
after it stops reaching the threshold before it is closed. You could increase this time to
3:19
make sure that a gate won’t close just because someone takes a lot of long pauses in their sentences.
3:25
If no channels are gated open, you could activate the "Last Mic On"
3:30
option which will keep the last open channel active.
3:32
This is useful for keeping a small amount of room noise alive
3:35
in the signal rather than cutting to total silence between speakers.
3:40
The middle section gives you control over each individual Channel,
3:43
of which we have four. At the bottom you could label them appropriately.
3:49
The meter in the middle shows you the "Signal Level Above Noise,"
3:54
or how loud each channel is over the Noise Floor. If this level is equal to or greater than the Threshold level,
4:01
then the channel will be gated open, and the Open LED at the top will illuminate to show that it is open.
4:07
You could nominate one channel as the Default channel, which will stay open when no channels are open.
4:13
This is mutually exclusive with the "Last Mic On" option: either you can have the last mic stay open,
4:20
or you could have a Default channel stay open,
4:23
so you’ll see that activating either option deactivates the other.
4:27
You can also manually force a channel to open by selecting the "Manual" button.
4:32
At the bottom of this section you can mute or adjust the gain of each channel
4:36
keep in mind that this is post-gating,
4:39
so raising the gain here will not increase a channel’s ability to reach its threshold.
4:44
The next section is the Number of Open Mics. Nom. NOM NOM NOM.
4:49
Like the Gain-Sharing Mixer, this mixer will attenuate channels when many are open at a time,
4:56
based on the settings here. Every time the number of open mics doubles,
5:00
one attenuation step will be applied to all channels.
5:04
So by these default settings, when we go from one open mic to two open mics,
5:09
each will be attenuated by 3 decibels. If we go from two open mics to four open mics,
5:16
each will be attenuated by 6 decibels, or two steps.
5:20
You can set a maximum attenuation that will cap these steps here.
5:24
If you activate Linear Attenuation, one attenuation step will be applied every time
5:29
a new channel opens rather than every time the NOM doubles.
5:34
You can keep track of how many channels are currently open
5:37
and the amount of attenuation applied to them here on the right.
5:40
You should note that any channels opened manually do not count towards the NOM.
5:47
This attenuation is applied to all of the component’s output channels.
5:51
In some scenarios, you may not wish to apply this attenuation to the direct channel output pins,
5:57
particularly if you are recording individual channels for archive purposes
6:01
you wouldn’t want the volume of that recording to randomly fluctuate
6:05
based on other channels that aren’t part of the recording.
6:07
If you deactivate the "Direct Outs NOMS Attenuation" button,
6:12
the direct channel output pins will keep their natural level.
6:16
You can also lower the maximum allowable number of open mics if you want to
6:20
limit the number of channels that can be open at a time.
6:23
If more channels are reaching their threshold than are allowed to be open by this field,
6:27
then the channel that has been open the longest will gate closed.
6:33
Finally, all that’s left is a master Mute and Gain fader for the "Mix" output pin.
6:38
The only thing left to mention is that the Gating Automixer incorporates a feature called "ID Gating,"
6:44
which determines which channel is the primary source of audio that is detected on multiple channels.
6:50
For instance, if a loud talker yells so loudly that he is picked up on multiple microphones
6:55
and reaches the threshold on all of them, the Mixer is smart enough to know to only open the channel
7:00
where he’s loudest, since this is the closest one to him.
7:04
That’s it for the Gating Automatic Mix Mixer. Thanks for watching, and we’ll see you next time.