Gain Sharing Mixer Control Panel
| Site: | QSC |
| Course: | Q-SYS Level 1 Training |
| Book: | Gain Sharing Mixer Control Panel |
| Printed by: | Guest user |
| Date: | Tuesday, 3 December 2024, 9:45 AM |
Description
Video Transcript
0:08
Welcome back. Let’s continue from where we left off.
0:11
Alright now let’s look at what’s happening in the Mixer itself. These are our four inputs,
0:17
each has an LED at the top that tells us whether or not the gate is open. If the gate is not open,
0:23
that line isn’t being mixed into the output. Right now Paul, George, and Ringo are all open, but John,
0:29
he’s floating in and out because he’s talking so low down at -20 decibels
0:33
that sometimes he’s gated open, and sometimes he’s not.
0:36
Now when more channels are open, each one will be attenuated a bit more
0:40
to keep the output level at unity gain – it’s sharing the gain across all the inputs,
0:44
that’s why it’s called the Gain-Sharing Mixer. All coming together, right?
0:47
Alright now each of these inputs also has a Priority Gain, this is how you compensate for quiet speakers.
0:54
So John is really quiet, we can turn up his channel’s gain so that now when he’s speaking,
1:00
you can see that his gate is gated open.
1:02
Now they’re all speaking right now, and you can see that Ringo is really loud
1:05
and he’s getting the majority of the gain, so they’re all in the mix.
1:09
But let’s find out what happens when some of them stop talking.
1:12
Let’s take out John and Ringo – you can see how Paul and George are being given more of the gain now.
1:18
In fact if only Paul is talking, then the mixer gives him even less attenuation.
1:23
but then they all start talking, and all they all start arguing
1:28
and you can see how the gain is dropped across the board. This way the output is never going to clip,
1:34
but when only one or two people are talking they’re given full volume,
1:36
and nobody has to be riding the microphone gains because it’s all done automatically by this digital mixer.
1:42
Now let’s look really quickly at some of the other options in the Mixer’s Setup now.
1:45
This Mix section lets you mute the entire channel, or change the gain on the entire mixed output.
1:52
The Open Threshold determines when the gate will open. If a channel’s Gain is above the number here,
1:57
then the gate opens – this lets you adjust how sensitive you want the mixer to be in order to open a gate.
2:02
So if I raise this threshold, their gates start to close
2:05
because they don’t have enough gain to reach the threshold. We’ll set that back down to where it was.
2:11
The Depth determines how much attenuation is applied to closed channels,
2:15
so you’ll see that if I have George start speaking softly, then his gate is closed,
2:20
and the Depth of -40 dB is how much attenuation is applied to his channel.
2:26
The Rest Gain sets a level for all channels when nobody is talking
2:30
that way it won’t be totally dead in between speakers so it doesn’t sound flat.
2:35
So we can see that by having everyone start to talk very softly
2:40
and you’ll notice that all of their channels are floating at around -30 dB.
2:46
The threshold level lets you compensate for background noise,
2:49
you can set this just above the background noise of the room to keep that from opening up your gates.
2:54
And these next few knobs adjust what happens when a gate opens or closes
2:58
the Attack Time is sort of a fade-in time, or how long it takes to open up the channel.
3:04
So if I set that really high, then you’ll notice that when George is loud enough to be opened
3:11
it takes a little bit for it to apply.
3:14
The hold time is how long the channel stays open after the speaker stops talking.
3:18
If I put this really high, let’s set it up to three seconds, it will take three seconds for the gate to close.
3:24
Let’s have George stop talking. One-one-thousand, two-one-thousand, three-one-thousand.
3:29
That’s how long it takes for the channel to turn off
3:31
that’s really useful if you know someone has long pauses in the middle of their sentences.
3:38
You don’t want them to be turned off mid-sentence.
3:41
And finally this Release Time is the fade-out, that adjusts how long it takes for a channel to close.
3:46
Oh and here’s the Detector Time, as we mentioned earlier,
3:48
this knob shows up and lets you adjust how long a noise has to be for it to count as an input.
3:53
Finally – we’re almost there –the Side Chain.
3:56
Like I said this lets you determine what type of noise opens the gate
3:59
you can set the frequency really high so that only higher-pitched noises will open the gate
4:05
now remember this doesn’t affect the line at all,
4:07
it just says what the mixer is looking for to determine if the channel will open.
4:11
There are some presets here, or you can adjust it yourself,
4:14
or if you don’t want to use it right now just hit the bypass button.
4:17
That’s the Gain-Sharing Automatic Mixer.
4:19
Alright let’s break real quick right here, and come back for the next part.
Lesson Description
This video explores the control panel of the Gain-Sharing Automatic Mixer and uses it to create a balanced output of four different mixed microphone inputs.Tips and Definition
Applied Gain / Attenuation: Displayed in decibels, the change in signal strength from the input of the mixer to the output. The Automatic Mixer applies negative gain (also known as attenuation) to channels to lower their volume and share the total output signal amongst all open channels.
Priority Gain: Gain, positive or negative, that is applied to a signal before it is analyzed by the Automatic Mixer for gating. This can be used to compensate for a voice that is softer or louder than others so that it will still reach the Open Threshold level.
Open Threshold: The decibel level at which a channel will be gated open.
Depth: The amount of attenuation applied to closed channels.
Rest: The amount of attenuation applied to all channels when none are open. This should be set higher than Depth, as this allows a small amount of background noise to be present when no channels are open, which prevents the overall audio from ever going “dead.”