Hey guys BigNate84 here
And welcome to Live Sound 101 schematics and block diagrams
In this video we will be talking about the differences between schematic diagrams and
block diagrams
And I will be showing you two examples of schematic diagrams
And three examples of block diagrams
When you are doing live sound it is important to have a good understanding of your signal
flow
That’s what we are talking about today when I’m mentioning these diagrams
We are talking about signal flow
And basically there are two ways I’d like you to think about it
Signal flow within a signal piece of equipment
And then signal flow within multiple pieces of equipment within an entire system
So in general when we are talking about a schematic diagram
We are talking about how the electricity flows inside of a specific device
And when we talk about block diagrams
It can be thought of in two ways
A simplified version of a schematic with less detail
Or a block diagram could represent signal flow within an entire system
And hopefully I’ll be able to explain that a little better in this video as we dive into
some examples
Ok lets take a look at the first example
This is a schematic diagram of a Neumann U89 condenser microphone
And schematics as you can see show signal flow on the component level within an electronic
device
They show how signal is routed inside this device
And it also shows various values of electronic components
This type of diagram is great for troubleshooting and fixing broken equipment
Every individual electronic component is mapped out
Potentiometers, diodes, resistors, capacitors, amplifiers, switches, that sort of thing
I’m not going to get too far into explaining the different symbols and what they mean
This is just an introductory course so I just want you to be familiar with it
But know that that’s what we are talking about here
So as we look at this diagram a general rule of thumb is that signal flows from left to
right
And this is true for schematic diagrams and block diagrams
Of course there are exceptions to every rule
But in general signal flows from left to right
So if we look all the way to left of this diagram here of the Neumann U89 schematic
diagram
We will see this right here
Now I am not an expert when it comes to electronics components
I know enough to be dangerous
But this represents the element of the microphone
So this is the part of the microphone where the sound energy
The acoustic energy is transduced is converted to electrical energy
And at the heart of it we have a capacitor
This particular microphone has a switch where you can change the pickup pattern of the microphone
And if we zoom in over here you can see these pick up patterns represented in this multi
throw switch
Ok lets take a look at another example of a schematic diagram
Now this diagram is for a Fender Bandmaster model 5E7 a guitar amplifier
And as you can see the input side is over here on the left
This is where the guitar would actually be plugged in to the amplifier
And you can follow the signal through all the electronics
And you can see all the different values
Now this is a major difference between a block diagram and a schematic diagram
Is that you can actually see that this is an 820 Ohm resistor
And this is a 100k Ohm resistor
So these types of diagrams are actually great for troubleshooting in case a component goes
The other thing, the other reason why it’s important to understand schematic diagrams
Is that symbols on here will correspond to switches, knobs and buttons on the actual
amp
So to understand how to make proper use of an amplifier
It helps to understand the schematic diagram
Alright lets look at some block diagrams now
This is a block diagram of a mixing board
This is a Mackie 32-4 VLZ Pro block diagram
And you’ll notice some differences right off the bat you’ll notice some similarities
too
Signal once again flows from left to right
So you can see the inputs are on the left and the outputs are on the right
And in the middle this mess of spaghetti is how the signal is routed
And one of the major differences you will notice
There is not the same nitty gritty detail as a schematic diagram
Values for every component are not listed here
This is more of a theoretical flow
It shows the major routing the important stuff that you really need to know
Without going into, how many Ohms is this resistor?
And sometimes you will have symbols like this triangle here is the symbol for an amplifier
And this resistor right here with an arrow
That means that there’s a potentiometer there
The arrow, that means that you can adjust the resistance here
And change the volume so that amplifier is adjustable
So that would mean that this right here is some sort of volume knob
This is actually the first volume stage or first gain stage once the audio enters the
sound board
So the trim knob would correspond to this symbol in the block diagram
And then after the trim knob or it could also be called the mic preamp
We’ve got the insert send
So this is a direct out right after the preamp
And you can maybe send this channel to a recording interface
Or some sort of recording device
Or you could send it to a processor like a compressor or a reverb
And then using a y-cable have that signal processed using outboard gear
And then input right back in through the same insert
And then the next thing the EQ section where you can adjust the EQ
And moving over you will notice the mute switch
The fader the channel fader
You will notice the pan knobs the potentiometers there that control
Whether the signal is panned to the left or to the right
And then you’ve got your routing section
This is where you can assign a specific channel to a sub mix
Sub one and two, sub three and four
Or the master left and right bus
And when we talk about signal routing we are talking about busses
So a bus is any place within a sound board where signal can be routed
And summed together and combined with other signals
This is where the magic happens this is where signals actually get summed together
Alright lets look at the next block diagram
This one is much more simple
Maybe I should have started with this one
This is a block diagram of a bass amplifier a Gallien-Krueger 400RB/210
So take a look at this we’ll notice differences between the schematic
There are not values assigned to every component
I mean there are some numbers here
We see a -10 dB pad we’ve talked about pads before
That will basically reduce the volume by 10 dB
So whatever you're inputting if the signal is too hot
And no matter how much you turn down the gain if it’s still too hot
You can push the pad and that’s going to bump everything down by 10 dB
So we've got the input, we’ve got the pad
We’ve got some light emitting diodes
You can see this little picture of a diode it actually looks like a diode
The arrow coming out of it means that it is light emitting
And then we’ve got the tuner
So you don’t have to run your bass through a tuner and then into the amp
But you can actually plug a tuner into this tuner output
And there is also a tuner mute button
There’s the switch right there
Then we’ve got the direct out so this bass amplifier is really convenient for live sound
people
Because you don’t need to run the bass player through a DI
It has a direct out, a balanced output, an XLR output built-in to the amplifier
So that makes it pretty handy I like that
Alright lets take a look at one more example of a block diagram
Now this one as you can see is a little bit different
It’s actually made of blocks go figure
You could have a block diagram with symbols that represent things
We mentioned the triangle represents an amplifier
The little squiggly lines represents a resistor
A diode is represented by a symbol that actually looks like a diode
With an arrow coming out of it we know that it’s a light emitting diode
But you can also have a very simplified block diagram
This is a block diagram of an entire system
So this is just a basic system that I created
I guarantee that if you work in live sound or you volunteer in live sound
You will be able to relate to at least some part of this block diagram
This is a very generic setup but a lot of people use something very similar to this
So let’s take a look at it we’ve got a microphone
And that’s plugged into a multi channel snake input number one
Then we’ve got a guitar plugged into a direct box
And that direct box is plugged into multi-channel snake input two
Then we’ve got a keyboard also going to a direct box
Going to snake channel three
And the bass amp going to snake channel four
And that’s all down on the stage
Now lets just say this snake is a 300 foot snake
So at the other end 300 feet away we will have channels 1, 2, 3 & 4
Plugged into channels 1, 2, 3 & 4 on the mixer
So then we are going to have a left output and right output
And that’s going to go to an EQ so we can do some master EQ’ing
Now this is where we would EQ for the room
And then of course we’ve got the two channel amplifier
Which is connected to a left speaker and a right speaker
And now down here we’ve got aux one and two
Which also would be going through an EQ to compensate for the room
And how the room is going to affect the sound
And you want to be able to have some control over that so you’ll run through an EQ
Some people like to do something called ringing out a monitor
So you might want to have some drastic EQ changes just for your monitor mixes
To mitigate feedback and get the volume up at a high level for your performers
Without experiencing feedback but we can talk more about that in another video
And next we’ve got a two channel amplifier and that’s going to monitor one and monitor
two
Monitor one and monitor two are just speakers
And you could think of them maybe as a floor wedge
A speaker sitting on the floor facing up at the performer
At a 45 degree angle or something of that nature
When we say monitors that is what we are talking about
A speaker that is designed to provide sound reinforcement for a performer
Now this all might seem intimidating if you’re looking at it for the first time
But after you study it for a while and really immerse yourself in the idea of signal flow
And you really think about what’s happening at different points in the signal chain
It’s going to click eventually it’s going to make sense
This might seem like a foreign language especially to a beginner
But I challenge you to open up the user manual and look up the block diagram
And see what’s happening to your signal
So that you can be in control of it
This is one tool that you should have in your tool belt
And that is the ability to read a schematic diagram
And at least understand how block diagram work
Alright guys when I get talking about live sound sometimes I carry on
Sorry if this video was a little bit long
But hopefully this introduced something new to you
That maybe you hadn’t thought of before
And hopefully I did a good job explaining when it would be important
To use a schematic diagram and when it’s important to use a block diagram
And just to recap if you want to understand a system
Or piece of equipment at a glance really quickly
A block diagram is what you want
On the other hand if you need all that nitty gritty detail
For troubleshooting or fixing a broken device
You’re going to want to reach for the schematic diagram
So that’’s kind of the difference between the two
Both are useful for different things
I hope this video got you thinking more about signal flow
And why it’s important for a live sound person
To really be able to understand signal flow
Thanks for watching