One summer I attended The Recording Workshop in Chillicothe Ohio. It is a school that teaches you how to be a successful recording engineer. They had vintage equipment in every studio, huge mic closets with any microphone you could possibly need, and studios with cutting edge technology.
But, before they would let us touch any of it though, we had to learn the basics.
The Basics:
We learned how a sound wave is formed and how it travels, and about the principles of acoustical and electrical energy. But the one major idea that they pounded into our heads throughout the entire course was the concept of signal flow.
The basic idea of signal flow is understanding how the audio signal moves from one piece of equipment to the next. With audio, everything has an input and an output. Think of the audio as a stream of water that travels along connections of pipes (cables) and faucets (mixers, amps, etc.) to its final destination.
Setup:
In order to grasp signal flow, let’s start with a basic setup. Someone on stage speaks into a microphone. The mic is attached to a mic cable that is plugged into a mixer. Cables run out of the mixer into amplifiers, and speaker cable connects the amplifiers to the speakers.
Now let’s see how signal flow applies to our basic setup.
The person on stage speaking into the mic creates our signal (input). The microphone turns his acoustical energy into electrical energy and outputs it to the mic cable. The signal travels down the mic cable and outputs it into the mixer.
Mixer:
When our signal reaches the inputs on the mixer, the audio flows through the mixer according to how it was set up by the manufacturer. On a generic mixer it might flow through the gain setting, then the EQ, a couple of aux sends, the channel fader, and finally the stereo bus. Each board is different so if you really want to know what order the signal is flowing through your particular mixer, I would recommend looking through the owner’s manual. Most of them contain the signal flow diagram of the mixer. Some new digital boards even have a screen that will show you the signal flow of a specific channel from the time it enters the board until it leaves.
So we have followed our signal along its path into the mixer, set its channel fader at a decent level, and now it is ready to exit the mixer. The signal leaves the mixer at the stereo outputs and into the cable. It travels along the cable until it reaches the inputs of the amplifiers. The amplifiers do their job of boosting the signal, and then the audio travels from the outputs of the amplifiers, along the speaker cable, and into the inputs of the speaker. The speakers then convert the electrical energy back into acoustical energy, and our signal flow journey is complete.
So What?
So how does understanding signal flow help you? Knowing signal flow enables you to quickly set up any audio system and be able to get signal flowing from the input source all the way to the speakers. Just remember that every step in the signal flow chain has an input and an output.
Ask yourself where is the audio signal coming from and where is it going?
Once you begin to understand signal flow it will also make troubleshooting problems much easier.
Since you know that the audio has to flow out of one piece of equipment and into another, anytime there is a problem just check the signal flow for “leaks.” Are you getting signal from other microphones into the mixer but not the lead vocal? Check each step of the signal flow (starting with making sure the mic is turned on), and eliminate each possible leak until you find it. Perhaps the receiver for the mic accidentally got turned off, or the mic cable plugging it into the mixer wiggled loose.
Study each piece of equipment in your system and think about how the signal is flowing through it. Begin to think of each input and output in terms of signal flow. And when the pastor’s mic loses signal five minutes before the sermon, you’ll know exactly where to go to fix it.
[Image from Andrea]
Stephen Bateman says
thanks greenhornet, btw what is your real name?
This semester I took musical acoustics at college. While I didn’t learn very much (I don’t think at least), we did learn that speakers can be moved less than half an inch and drastically reduce the sound quality.
Sound I think is under appreciated
greenhornet79 says
My real name is Jeremy Green. I’ve always used greenhornet79 for everything online, so when I signed up for a WordPress account I used it. Maybe I should have used my real name, but oh well. 🙂
I agree. You could study sound all your life and still learn new things.
Justin Piercy says
So true. Whenever I’m training/apprenticing new team members for our audio crew this is the first thing I get them working through their heads. Once you understand how the system as a whole flows, it becomes a simple matter to diagnose any kinks.
I got the same training when I attended school for audio engineering, and I wish more people placed importance on this. Great post.
Travis Fish says
Love the post man. Thanks for the insight into sound!
greenhornet79 says
Thanks!
Kosmik says
A well-done article!I am currently studying sound engineering,and this really helped!