Hey guys BigNate84 here
Thanks for joining me yet again in another episode of Live Sound 101
And in todays video we will talk about what actually defines a live sound system
And we will talk about how live sound or sound reinforcement
Is a specific type of sound system
There are many different types of sound systems
So we’ll talk a little bit about
What makes live sound unique and sound reinforcement unique
And we will also take a look at a signal flow diagram
So we haven’t really gotten into the good stuff yet
The meat and potatoes of live sound
And later on in this series we will cover mixing technique
And logistics and approaches to live sound to be successful
And create a good mix and be able to direct people
And get a good microphone test out of them
Sometimes the performers can be difficult to work with
To try to get a good sound check can be challenging
So we’ll talk about all that stuff later
And EQ and settings levels and all that good stuff that’s coming later
But right now in these first few videos
I want to lay down a good foundation of knowledge
So that you guys can feel comfortable mixing
And really understand the systems that you are running
If you happen to be an operator of a live sound system
So anyway to recap what we have gone over so far in the first video
The introduction we talked about using your ears, listening, understanding music
And I gave out some recommended reading
In the second and third video we talked about some lingo and jargon
And some terms that you should know
And by no means is this a comprehensive list
It’s just to get you started to give you something to chew on
We will be adding to this terms library as we go throughout this video
So we will be constantly learning new things learning new terms
As it becomes applicable in this video series
And in the fourth video we learned about
Three common analog audio signal types
Now, why is it important to know the difference between these analog audio signal types?
How do they fit into the picture of live sound?
How do they fit into the big picture of live sound?
And what is sound reinforcement?
So that’s what we have going on in this video right now
So many types of sound systems exist
You could have a sound system in your car, a sound system in a movie theater
A sound system in an airport or in an auditorium
Now each of these will have some similarities and some differences
Depending on what the needs are so when we talk about sound systems
Or specifically sound reinforcement systems we are talking about live sound
So there is acoustic energy that you are capturing
Converting that into electrical energy, manipulating it
And then converting it back into acoustic energy
So that is the basic premise of sound reinforcement and live sound
So lets take a look at a little diagram I put together to better explain this
And hopefully tie everything together
So we’ve covered the analog audio signal types and you’ll see them in this diagram
right here
But basically as I just pointed out you’ve got low level acoustic energy in a room
And you are capturing that energy with an input transducer
Converting that to electrical energy
You are then manipulating the electrical energy
Through signal processing, through mixing, through amplification
And then you are finally converting back to acoustic energy
But to a higher level acoustic energy
And that is basically what makes a live sound system
Or a sound reinforcement system unique to some of these other systems
That you might find in a car or in a classroom or in a home theater or a paging system in
an airport
Although that does have some element of live sound to it
It is just a slightly different set up
Sp why is it important to know the difference between these analog audio signal types?
Well as you can see the signal starts out coming from the microphone
As a low level microphone signal
And the mixer is designed to accept that signal
The mixer then outputs line level signal that the amplifier is designed to accept
And finally the amplifier outputs speaker level signal
That a speaker is designed to accept
So that’s how these signal types fit into the big picture of live sound
That’s why it’s very important to know the difference
Because you cannot just take a microphone and plug it into a power amplifier
And you can not take a power amplifier and plug it into a mixer
You need to match the signal types according to how the gear is designed
Coming to the end of this video I did want to address some questions
Brought up from a user on YouTube
And his name is Mothy Mothy, and as this video series continues
If I get some good questions I will take some time to address them
Towards the end of each video
So he was asking about +4 dBu and -10 dBV
He had a mixer that had a switch on the back
And the switch meant that he could choose what type of signal the mixer would output
And he could choose between +4 dBu and -10 dBV
And he asked me what’s the difference between the two and what should I use?
And he then pointed out that when he uses +4 dBu it sounds much better
It sounds much cleaner its a much clearer signal
But then when he uses -10 dBV it sounds noisy and it doesn’t quite sound right
And so I asked what speakers are you using?
What’s in your system?
And he said we’ll I’m going from this mixer to some powered speakers
Some Mackie powered speakers and I looked up the speakers
And the spec sheet said that they had a sensitivity rating of +4 dBu
So there’s your answer right there
The speakers were powered speakers meaning they had an amplifier built into them
Also called active speakers
So they we ready to accept a line level signal, but a professional line level signal
A +4 dBu line level signal that’s the sensitivity rating
That’s what they were designed to accept
And he even pointed out that it sounded great when he switched his mixer to output +4 dBu
As a nominal operating level
Now when he used -10 dBV it didn’t sound quite right
Now that’s a different reference voltage
So we have +4 dBu and -10 dBV the difference between those two types of signal
Is the “u” and the “V”
So the “u” stands for unloaded in +4 dBu
And the “V” in -10 dBV stands for voltage
And -10 dBV has a zero dB reference voltage of 1 volt
+4 dBu has a zero dB reference voltage of .775 volts
So what we are talking about here is the difference between consumer level line level
Sorry that was too many levels there
Consumer line level and professional line level
And basically you need to understand your equipment
And understand whether it’s professional, consumer or a combination of the two
And know how to match signals accordingly to get the best possible quality audio signal
Ok guys hopefully that all made sense to you
Thanks for watching, keep bringing your questions
And stay tuned for the next video