YHS Sound Tech Manual

The first thing you need to know about are the audio connectors. The primary connectors we will be using are the XLR, the phono also known as an RCA jack, and the 1/4 and 1/8 inch phone jack.

One skill we will need to work on for anyone doing audio work is the ability to use a soldering iron. Soldering is commonly used to connect wires to the audio connectors. Soldering is connecting wires to terminals with melted metal. We will be using a tin/lead solder to connect the wires to the terminals.

I have included one short explanation from How to Solder Stereo Mini Plugs . This is a good but simple explanation of how to use a soldering iron. For a better explanation I recommend Media College's explanation of How to Solder.

For this discussion we will confine our selves to the types of signal levels common in a theater or auditorium. If we were to get into signal processing at some point we will expand on these levels.

So the signal levels we will discuss are called microphone level, and line level. In electronic terms these levels are about 1 millivolt and 1 volt. The main difference is that the microphone level is the direct output of a diaphragm, while the line level is what you would get from a small amplifier. Here is an explanation of how a dynamic microphone works.

The other difference in the signal types is balanced or unbalanced. What this means is the signal coming from a microphone is carried on two wires in a push pull style. Clear? I thought not, lets try a picture of s transformer setup.

The signal is carried on both the hot and cold wires. This balanced output is designed to reduce the amount of interference since it is generated equally on each side of transformer. Not to worry if this is not totally clear. It is most important that you understand what balanced inputs are not how they deal with noise canceling.

The other style of audio is known as single sided. That means that the signal is carried on a single wire not two. Typically the output of an amplifier or pre-amplifier.

For our uses we need to understand these basic two signals since they are what we are putting into and taking out of the mixer. On the back of the mixer are inputs for microphone and line for each input channel. The signal coming from the mixer to the power amp is a line level signal.

The gist of connections is knowing how to go from one signal source to another using the cables we have. The point is that the sound person is expected to be able to hook up the various sound sources to the main speakers. So to understand how to do this lets go through a series of cases and talk about how we get there.

First lets make a couple of assumptions. Most of the sound in the auditorium is Mono. We do this by choice. Except for some prerecorded music, the audience is more interested in hearing all the sound rather than any stereo effects. By default we will assume any sound input wants to come through the main house amp and speakers. We will ignore monitor speakers for the present.

Lets start our discussion of the equipment by learning how to use the mix desk. Here is a picture of the inputs with some numbers for discussion.

Our main interest goes to the Microphone inputs, Number 9. These XLR connectors are normally connected to the microphone snake coming from back stage. The numbers on the connectors correspond to the numbers on the input box back stage, not the channel of the mixer.

The other input point is the line inputs, Number 8 and 12. These inputs is where we would connect tape recorders, or CD players, or laptop computers. These jacks are 1/4 inch MONO phone jacks. Both the microphone input and the line input is connected before the trim pot.

The inputs labeled insert, Number 14, are for special effect tools. This is where you would use a reverb or delay line. For our purposes we will not deal with these connectors.

The Aux outputs, Number 17, is where we will connect the back stage monitor amplifier. If we were feeding sound to another source, such as a video camera, we would use one of these aux outputs. We have 4 which are easily controllable from the console.

The main outputs, Number 27, are what we will use to feed the house amplifier back stage. It is arranged so the audience left and right are the speakers feed from the desk.

Starting at the top of the module we have the trim pot, Number 13. This sets the input gain from the microphone or line input.

The slider is number 42. This is the main control for each channel. When running a show, this should be the only part of the channel you change.

The 4 buttons, number 41, select where the output of the channel is sent. Typically it would L-R, which is directly to the master volume control. If you wanted to monitor the channel through the headphones but not the main speakers, you could use the solo button. The others buttons, 1-2, and 3-4, assign the output of the channel to a pair of submaster sliders. Remember that you can use the pan pot to assign the channel to only one of the submasters. ie. pan pot left, button 1-2, will send the output to only submaster 1.

The led indicators on the channel are muted, number 43, and solo/activity, number 44. The muted led, indicates that the channel is silenced. This is accomplished by pressing button 45. This is useful for channels you are not using, or when connecting equipment to the channel. The solo/activity led has two functions. When you press the solo button it connects the channel to the headphone jack, but not into the house. When you are not in solo, the led indicates activity on that channel.

The pan pot, number 46, moves the channel between the output pairs. For example if you have the button 1-2 pressed, then the pot will move the output of the channel between the left are right sides of channel 1-2. Think of this pot as a balance between the stereo channels.

The three band equalizer, Number 47, allows you to tune the sound to the maximize the sounds by adjusting the frequency response of that individual channel. For speaking voices, or singing voices we should be careful since we are changing the way someone's voice sounds. So the use of this equalization should be minimized unless you are sure what you are doing. Sometimes these can be set to minimize feed back, but there is not much else we should be doing with these controls.

The low cut filter, Number 48, will help eliminate some of the microphone noises. This frequency range, below low cut, is only useful for base drums. So we should probably leave this on all the time.

The Aux Send pots, Number 49, control the level of the signals sent to the Aux outputs. We use the first channel for the back stage monitor. The other channels can be used for a video sound feed or other outputs.

The Pre button, Number 52, simply connects the Aux outputs either before or after the equalizer. We do not need this functionality. Also the 5/6 shift button, Number 53, allows control over two more aux outputs. We are probably only going to need 2 aux channels, so this button is not needed either.

Main L-R Mix Fader, Number 54, controls the total output which is what we send to the main amplifier for the house speakers. The typical setting for this slider is at the U. U stands for unity gain. Think of it as the zero point

The submaster sliders, Number 56, are used to group a set of input channels into a sub group. This is valuable when you need to combine a group of mics or inputs into a single slider. You then use the assign buttons, number 57, to select which side of the master slider the output goes to. For example, suppose you had 5 mics assigned to a chorus. You could assign these 5 input channels to submaster 1-2, and use the submaster to bring those mics up and down together. You would then assign the submaster 1 to Left and submaster 2 to right. The output of the submaster is then fed to the master volume control.

The source buttons, Number 61, select what sound is routed to the head phone jack. Either main mix, sub master 1-2, sub-master 3-4, or tape. The volume pot, number 62 controls the volume of the head phones.

The Mode/Level Set button, Number 63, should normally be in the up or mode position. This will allow you to monitor any channel using the solo button and the head sets. The solo volume, Number 65 is to set the volume of the solo output.

The Aux sends, Number 69, is where you set the levels for the back stage monitor or the video camera. The solo button below them allow you to pipe the output to the headphones to check what you are sending.

There is not a lot to say about the amplification and speakers. We currently have 2 back stage amplifiers. The Crown amp CR-1010 drives two Yamaha S115A speakers on each side of the stage. The other amplifier currently only drives a single back stage speaker as a monitor. It has a second channel which we are not using at this time.

One of the first things to think about when placing a microphone is the relationship between the microphone and the speaker. Generally you want the mic to be right in front and slightly below the person's mouth. This allow a clear view of the speaker's face, while maximizing the sound. Here is a drawing.

The next situation we will look at is a several singers, each using separate microphones. We need to space the microphones far enough apart to minimize picking up one singer in another singers microphone. Again the best explication is a picture.

The next situation we will deal with, for now, is how to record a group of singers. Lets assume you wanted to record a chorus on the stage. The trick would be to use two over head microphones pointing at the singers. For this application we could use two condenser microphone hung from a over head pipe. Here is a picture of what I think would work.

This subject is quite broad as any recording engineer can tell you. If you want a good place to get more information, I recommend the Shure Educational Materials which is where I got the pictures used above.