Out Of The Mixer
The signal can travel out of the mixer in a variety of ways;
—Auxiliary sends. This could be for monitors, hallways loudspeakers, or however your system is set up.
—Tape deck. Yes, some mixers have separate send controls for tape decks. Really, they could be used for any device but yes, they might be marked on your mixer as “Tape controls.”
—Insert loops. These are at the channel level and are used to send the signal out to a processing unit like a reverb unit, and then return that sound back into the channel at the same point.
—Group ins/outs. You can send the specific group signal to a separate out. For example, a group could be used for additional signal processing like a compressor and therefore you can route the signal out to the unit and back in. Or, route it out for some other use.
—House loudspeakers. You gotta fill the room with sound!
The output signal can go directly to another processing device, like a reverb or compressor as I mentioned above. Or, it could be routed for your house loudspeakers. It’s here where you need to dive behind your components and start following some cables.
Audio signals can be routed a variety of ways. I’ve seen systems where the main out was first routed through a tape deck before going to the amplifier. Such routing is understandable considering the fact that you commonly want to record a service.
However, for more finite control, they could have routed the recording device to an auxiliary channel where the mix for the recorded media could have been different.
Note that the signal strength between components is considered to be at line level.
You should expect the mixer’s main output to go out to the house EQ, through any house compressor or limiter, and then to the mixer.
What To Do When The Volume Stops
Knowing how sound travels through the audio system, you can quickly find the source of audio problems. Take, for instance, an electric guitarist who has started playing during the sound check but you don’t hear them in the house mix. By tracking the audio signal from its source, you can investigate where the problem might be located.
For example, if you are getting a green light on the channel, you know you are getting a signal from them. Perhaps the gain is too low. Maybe you aren’t getting any signal light. Start at their guitar and make sure the signal is taking the right path to the sound booth. It could be a mistake as simple as improper cabling into a direct input box.
When The Sound Is Bad
Every time an audio signal goes from one component to another, you can pick up unwanted noise. This is called line noise. Regarding the signal flow coming from the stage, we need to look at something called the signal-to-noise ratio. In short, this ratio explains the quality of your sound.
For example, let’s say you have an acoustic guitar with an on-board amplifier. This gives the musician the ability to control the level of the signal from their guitar. If they don’t raise the on-board amp’s volume high enough, you could hear a large amount of noise in their signal. By increasing the volume on their guitar amp, they are improving / increasing the signal-to-noise ratio. This means when the signal is amplified, there is very little noise heard because the strongest signal is coming from the guitar.
Summary
The flow of the audio signals through your system can take different paths. There is an order to the mass of cables running to and fro. You can have a great grasp of how your system works when you know how your audio signals are routed.
Ready to learn and laugh? Chris Huff writes about the world of church audio at Behind The Mixer. He covers everything from audio fundamentals to dealing with musicians. He can even tell you the signs the sound guy is having a mental breakdown.