Video Transcript
Gain Sharing Mixer Setup
4m 6s
0:08
Welcome. Let’s talk about a few of the automatic mixers that are built into the Q-SYS Designer software,
0:14
specifically the Gain-Sharing Automatic Mixer and the Gated Automatic Mixer.
0:18
Now both of these mixers adjust their output gain to
0:22
your desired level by varying the attenuation of their inputs. Now this can be useful in a lot of situations
0:28
when you may have multiple people speaking using different microphones,
0:31
and is a lot easier than having someone manually adjusting those mic levels.
0:35
Because this is voice activated, it ensures unity gain at all times. So let’s set up a system.
0:41
We’re going to click on the Schematic Library, go under Audio Components, Mixers,
0:48
and drag a Gain-Sharing Automatic Mixer into our Schematic.
0:52
Now since we don’t have anyone actually talking into microphones we’re going to duplicate that effect
0:56
by using some Pink Noise Generators to represent human voices.
1:00
So you can grab those from Audio Components, Test and Measurement, Pink Noise
1:04
and I’m going to make four copies of these to represent four people that we’ll be using in this design.
1:11
Now if you hit the space bar you can rename them – so I’m going to give each one of them a name so
1:16
that I can remember them a little bit easier down the line when we are showing you how this works.
1:22
Those are some good random names right there.
1:26
And of course if you want to, like any component, you can change the colors of these,
1:28
that might help you remember later on which one you’re affecting.
1:32
Alright now the next thing that we’re going to do is take a look at the Gain-Sharing Automatic Mixer component.
1:38
Now over here in its Properties Panel we’ll set the "Channels" field to 4,
1:43
‘cause that’s how many microphones we’re using today.
1:45
You can see now there are only going to be four input pins on the Mixer.
1:50
We’re going to wire our four speakers to these input pins.
1:53
John will be in input pin 1, Paul is input pin 2, George is input 3, Ringo is input 4.
2:00
Now you may notice there are actually five output pins – that’s because each input has a direct line out,
2:06
and the last output is the mixed line, that’s the one that we’re going to be wanting to use.
2:11
Let’s take a look at the functions on this mixer over here in the Properties Panel.
2:15
Like any component you can change the color by using this Fill option,
2:19
and we’ve already adjusted the Channels field to change the number of inputs.
2:23
We can also choose which outputs are available,
2:25
let’s change ours to Mix Only since that’s the output that we want to use.
2:29
Next is the Side Chain Filter – this will open or close another window in your Mixer’s Control Panel
2:35
that lets you choose what bandwidth and frequency you’re looking for in order to open the gate on someone’s mic,
2:40
we’ll set it to Yes just so that we can take a look at that later.
2:43
And lastly there’s "Detector Time," this sounds like Sherlock Holmes’ battlecry,
2:48
what this does is it looks for momentary non-vocal spikes in the signal that
2:52
might accidentally open the gate when it shouldn’t – this could be a random digital blip
2:56
or maybe a person coughing – that might otherwise make the mixer think that someone’s talking
3:01
and open the gate, well Detector Time lets you fine-tune how long a noise has to be in order for it to count.
3:06
You can select 10 milliseconds, 20 milliseconds, you can adjust it however you like or select Use Control.
3:12
That will give you another knob in the Setup section of your Control Panel that lets you pick it manually.
3:17
So let’s see this Mixer in action. We’re going to load our design to the Core,
3:21
you could go to File, Save to Core and Run, or you can use F5 – that’s your keyboard shortcut.
3:27
Now once we get there, we are going to double-click on each of our four presenters
3:31
so that we have access to their levels, and maybe we can mute them as well.
3:36
We’re going to give them a variety of volumes, let’s say that Paul speaks at about -10 dB
3:45
George speaks at about -15 dB, John’s, let’s put him at -20 dB, and Ringo’s really loud,
3:55
we’ll put him all the way up to positive 1 dB.
4:00
Alright, why don’t we put a pause right here, and you can go on to the next part whenever you’re ready.
Lesson Description
Gain Sharing Mixer Setup
4m 6s
Sets up a sample system involving a Gain-Sharing Automatic Mic Mixer and four Pink Noise Generators to simulate four microphone inputs.
Tips and Definitions
Gain Sharing Mixer Setup
4m 6s
Gain-Sharing Automatic Mixer: This component gates its various input signals open or closed based on their audio signal, and applies attenuation to these signals to share the output gain amongst all open channels.
Pink Noise Generator: This component produces random frequencies that are distributed uniformly across each octave band. In this exercise they are used to produce noise representative of a human speaking into a microphone.
Detector Time: The length of time that an audio signal must reach its threshold before it qualifies as a valid signal. This prevents short, non-vocal spikes from erroneously opening a gate.
Downloads and Links
Gain Sharing Mixer Setup
4m 6s