A Musician’s Intro to Live Sound

By Neal Humphrey, Flashband founder

The Family Hammer, my bluegrass band

When my first band started doing our first shows, we usually had to run some or most of the sound ourselves. I quickly found myself in the position of being one of the primary “band sound engineers,” even though I knew nothing about live sound.

Every band seems to have that one person who’s just a little more technically-minded and makes an effort to try to figure stuff out themselves. Pretty soon, everyone else in the band assumes that he or she is the go-to person for all things tech. It took a lot of stumbling and Googling and reading in order for me to start to feel like I knew what was I was doing. With this series, my goal is to save you some of that trouble. 

Musicians often don’t get a formal introduction to how live sound works – ever. It’s more of a sink-or-swim thing. While this is a huge topic (so big that textbooks have been written about it), some fundamental basics can go a long way in helping you, the musician, to fake it a bit better, and to not work against your sound engineer. Along the way, I’ll highlight key takeaways for someone that’s performing on stage. 

Let’s start with the fundamentals.

A live sound setup has an input side (you, your instrument, microphones, etc.), some stuff in the middle, and an output side (speakers). Everything on the input side of a live sound setup takes vibration: through the air, like sound going into a microphone, or physical vibrations, like the string on your guitar. The setup converts it into an electrical signal. But the inputs vary, both in how large that signal is and what the signal “looks like,” or the frequencies it contains. 

Everything in the middle is designed to adjust all the various input signals into a combined electrical signal that contains an appropriate mix of all the inputs. The speakers then convert that electrical signal back into sound.

Inputs: Vibrations are captured either as air vibrations or mechanical vibrations, as we mentioned above. All of these things produce some electrical signal as an output. The biggest source of confusion here is the type of electrical signal produced by different types of input equipment – line level vs. mic level vs. instrument level, balanced vs. unbalanced. We’ll cover all that in a bit. 

Transmission: This is the fun part, and also where things get confusing. Remember how different input equipment creates different types of electrical signals? The purpose of the rest of the equipment on stage – cables, DI boxes, mixing boards – is to bring these different signals into one place, convert them to the same type of signal, and send one unified signal to the speakers. All the components of the live sound equipment are designed with a specific signal type in mind, and the biggest cause of frustration is when you don’t understand what types of signals that each piece of equipment is using.

Output: In live sound, speakers have two functions: for the audience to hear you (duh), and for you to be able to hear yourself. The biggest cause of problems with speakers is actually the room you put them in. Sound bounces off the walls and echoes everywhere, people talk louder to be heard over the sound, and suddenly your ears are hurting but you still can’t hear the music clearly. This is a pretty complicated topic, so I’ll just point out a few key things to keep in mind.

The biggest principle I wish I’d understood early on is the difference between all the signal types in a live sound system.

This is one of the main reasons we need different types of equipment on stage, and we’ll reference these types throughout this series. The two biggest distinctions you can make in signal type are:

Level

• A microphone-level signal is very small (millivolts) 
• Instrument levels vary, between mic and line 
• A line level signal is medium (1/4 to 1.5 volt) 
• Speaker level signal is large (10-100 volts) 

These are usually reported in decibels (dB) rather than volts. Decibels are always measured in comparison to something else. Ever seen -10dBV or +4dBu on your gear? That’s telling you what the line level signal type is. Audio equipment has “pro” and “consumer” versions, which are, annoyingly, different. If you want to hear the technical details, this post is a good start.

For most musicians, it’s enough to just think of it like this:

Balanced vs. unbalanced

Another big distinction is balanced vs. unbalanced signals. A “regular” signal is unbalanced, and it just sends the signal one time. So why would you need a balanced signal?

When you send that signal through a cable, the cable also acts like a giant antenna, picking up noise from radio waves, cell phone towers, other cables nearby, etc. The longer the cable, the more noise. When the signal is large (speaker level!), this is no big deal. When the signal is small (mic level), the noise is a big problem. Balanced signals are designed to remove the noise. Basically, a balanced signal sends the same thing twice with the second signal flipped so that the noise cancels out. When you have a small signal level or a large distance, you need a balanced signal.

This video is a straightforward summary of how it actually works (but please excuse the 1995-style intro):

Now that we have some common fundamentals, it will be easier to explain what each of the components are, and what you as a performer need to pay attention to. In the following posts, we’ll dig into each of the three sections of the live sound system and cover what a musician really needs to know.

Next post - Inputs