Live Sound Overview: Gear Protection

Updated: Oct 22, 2019


This outline on live sound focuses on setup, setting levels, signal flow, and breakdown for gear protection.


There should be no other signals being sent to the speakers if powering up or down.


When shutting down equipment, turn off speakers first. When powering up, turn on speakers last.


This ensures there is no surge of signal from any potential source.


Speaker placement should reflect the way minds process the sounds via arrangement of frequencies.


So highs up top mids in middle, lows on bottom.


From there speakers should be arranged however is best for audience to hear.


Spatial awareness such as cushioning sub woofers or not having speakers touching any surfaces like directly on the ground or being obstructed by other objects can prevent issues such as muffling, rattling, etc.


If live sound setup were a human body: the musician would be the brain, the instrument or controller would be the heart, the signal flow or power would be blood flow, cables would be blood vessels, and the speakers would be the organs.


A number of factors could impact blood vessels’ ability to send blood to organs such as blood pressure, circulatory issues, or bleeds. Same for cables and electricity.


The musician as the brain sends information to the instrument as the heart about how much blood or current to push through to the speakers as the other organs.


Not properly wrapping cables or allowing cables to become knotted is like clamping a blood vessel but then expecting blood to still travel to and from the organ.


Clipping is like allowing an organ to bleed internally which can be very bad and can cause the organ to fail.


Clip lights can either be dealing with headroom or the fact that the signal is about to actually clip.


Headroom goes back to analog monitoring which refers to decibel levels above unity gain that are safe before clipping.


Unity gain refers to having an input and output at the same voltage and impedance so that the signal going into the mixer is what is coming out.


The more gain that can be achieved cleanly and without distortion, the better the mix sounds as well as the safer the equipment is.


Level setting procedure assures low noise and high headroom meaning the ability to raise the signal as much as possible without distortion or blowing anything by sending too much power.


Setting levels should be performed one channel at a time and then as an entire mix.


1. Set all faders, effects, and sends to neutral detents.


2. Be sure any signal processing or assignment switches are disengaged.


3. Connect the signal source or load the track to software (such as Serato/Traktor).


4. Play the instrument or track to each line channel input by slowly raising the fader to real world levels optimally by monitoring the meters.


5. Adjust main mix faders as channels/instruments are accommodated to hear quality and check signal flow as a cohesive project.


The meter display reflects what the engineer or DJ/Producer is listening to by measuring the sound levels via decibels and volume units with various standards.


For example, the difference between a +4 mixer (+4dBu = 1.23v) and -10 mixer (-10dBV = 0.32v) is the relative 0dB VU (or 0VU) chosen for the meter display.


A +4 mixer, with a +4dBu signal coming out, will actually read 0VU on its meter display.


A -10 mixer emitting a -10 dBV signal will read 0VU on its meter display.


Another example of a mixer’s metering would be the ones that calls things as they are and 0dVu (0.775V) at the output shows as 0VU on the meter display.


Most amplifiers clip at about +10dB, and some recorders aren’t so forgiving either. For best results, try to keep between 0 and +7.


Meter displays are just tools to monitor levels. They do not need to be stared at, but they do need to be adjusted at the introduction of each new sound (whether that is instrumentation or song) which is called gain staging.


The concept of gain is a device’s ability to take the lower level of one signal and bring it to a higher voltage level the same way the goal of this post is to bring sound design skills to another level.


Notes:


*Microphones are a whole nother side quest, and could be addressed in depth for ever


*It is important to do an initial soundcheck with a clean signal without any effects to set baseline levels for the signal at its most original form.


*Each chain of effect changes the signal (one of many reasons setting levels is not something to set it and forget it).


*The difference between setting levels for live sound versus setting levels for recording is that in live sound the main outputs are the speakers while in recording the main outputs are the tracks in the DAW.


*Therefore in live sound techniques the focus is getting as much signal as possible without clipping by slowly introducing the signal to avoid damage to gear or ears.


*In recording techniques the focus is to record as much as the signal that is present as possible without clipping by slowly lowering the signal so that there is whatever information possible downloaded into the file.


*Recording studio techniques come back to painting an aural landscape and live sound for musicians/DJs that sample a specific mix or master.


*Researching recording studio techniques can help with gain staging because it provides a better understanding of signal flow.



Recommended Readings:


1. Pow! Pop! Powering Equipment On and Off in the Right Order

2. Audio Cables: Everything Musicians Need to Know About Audio Cable Types [Infographic]

3. Everything You Need to Know About Gain Staging

4. Gain Staging Like a Pro

5. How to Use Dynamics Processing: Getting Started with Compressors, Gates, and More

6. Audio levels, dBu, dBV, and the gang: What you need to know


Relevant Online Classes:


1. Ultimate Live Sound School (1st Edition)

2. Audio Engineering: Signal Flow

3. Live Sound: Mixing and Recording

4. Mixing and Mastering for the Electronic Musician

5. Introduction to Audio Engineering

6. Operating the Audio Mixer, A Beginning Sound Engineer Course

7. Digital Audio Engineering + Music Production Reference Guide

8. Audio Engineering: Adjectives of Audio

9. What is sound?

10. Learn Compression & Dynamics Processing: The Complete Guide