SECTION 3: GENERAL INFORMATION
Maybe you don’t need to read this at all.
Many of you reading this
manual have a lot of experi-
ence in using mixers and
mixing consoles. For you
For those of you who are either new to using mixers or just like to read even larger quantities of our glib prose, we’ve provided this short sec- tion. It discusses the basic concepts and procedures used in recording, mixing and sound reinforcement work. If you can make some sense of it, you can check out your application and patching in Section 4 and start plugging things in.
GENERAL INFORMATION
Here is a primer covering a few important ideas you should be on good terms with before you sit down to a mixer.
LEVELS
Microphones have low output levels. Line level devices have high output levels. One of the functions of a mixer is to amplify or attenuate these signal levels properly. Since it’s easy to degrade the signal by not handling levels well, and since it’s your hand on the knobs, you should be sure you know how much gain to apply and where to apply it.
Note: No matter what
combination of cable
adapters you may have at
hand, never connect the output of a power ampli-
fier to the input of a mixer.
Noise
Every electronic circuit produces noise or hiss or hash or buzz, and any noise present on the input of an electronic circuit will be faithfully passed through. Turn it up high enough, and you will hear the noise.
Headroom
Every electronic circuit also has a point of overload, a clip point, where the voltage simply cannot rise any higher, no matter what the input signal and your fader move would like. This overload, or clipping, will show up as tooth-
grinding distortion.
Somewhere between the noise and the clipping is an optimum level for your signal: high enough above the noise floor to render the hiss inaudible, and far enough below the distortion point to allow range for loud peaks of music to pass without clipping. This safe operating zone might be called operating level or nominal level or zero or perhaps line level. The range between your operating level and clipping is called headroom, which defines just how tall your signal can be without having to duck for the rafters.
Your mission as a designated Master of the Levels is to get the low level signals up to line level as soon as possible and to keep them there as much as possible, but not to turn them up too much.
Unity Gain
On a Mackie mixer, the easy way to do this is to set all the level controls in your path to the “U” marks screened onto the panels. Set the Balance control to the center and press the channel Solo button. This will display the channel level on the Left and Right meters. Then adjust the channel Gain or the Mic trim until you have a good level on the meters. The “U” stands for unity gain, which basically means level in = level out. Now, with mic inputs that’s not exactly the case, but ignore that and set your faders at “U”. That will get you in the safe zone.
Metering
Pay close attention to the meters. A meter is an aid, a window looking onto part of the dynamic range of your signal, and it will tell you if your level is in the ballpark, so to speak.
Try to keep your signals in the middle range of the meters, for the most part. If the signal is always very low, you may not be getting the best
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