There is no perfect situation for sound reinforcement. Even when a skilled and savvy engineer comes in and saves the day they may still be greeted by the noise of ungrateful crowd members complaining about the sound quality. But hey, nobody said this was an easy job.
by Micky Sierra & Alfonso Salinas / Photo: SAE Institute Mexico
I have the pleasure to teach the live sound reinforcement class at SAE Institute in México City. My priority is to help students obtain real hands-on experiences by putting them on the spot, in front of a real situation. They must contend with the challenges that we professionals encounter in ‘the real world’. The class is a combination of both classroom work, and practical training.
There’s a lot of information and concepts that students need to understand, even before they slide the first fader; decibels, inverse square law, acoustics, sound pressure levels, dynamic range, signal flow, amplifiers, or speaker systems. On the other hand, if we only talked about theoretical principles without any professional exposure my class would be just repeating information you could find in the best available audio books. I believe students need as much practical training as possible and the results can be really eye-opening for some students.
There are many similarities between live sound reinforcement and a studio setting, a signal flow is a signal flow. However a live situation might not be so forgiving when mistakes are made and staff are overcome by stress.
One key concept of my class is the difference between indoor and outdoor sound. Both situations have pros and cons. For instance, sound indoors will present more acoustical issues and considerations such as potential standing waves, long RT60 times. But indoor venues will have isolation from exterior noises such as airplanes, car horns and street noises. This will result in a bigger dynamic range to work with, a lower noise floor.
Sound outdoors can be quite a treat since acoustical considerations can be minimised. We still get reflections from the floor, some buildings and any surrounding structures. However this is nothing compared to a closed venue, especially the ones that resemble reverb chambers. On the downside, when outdoors we will most likely need more sound pressure level (SPL). This is not cheap as bigger and better speakers and/or
line arrays, depending on the crowd depth will be needed. There may also be the need for some delay fills, more power to drive those speakers, a smaller dynamic range due to background noise, not to mention the climate considerations. Wind can be quite the enemy due to sound refraction. Temperature and humidity influence sound refraction as does speed and air absorption.
A savvy engineer needs to deeply understand what a graphic EQ does, what a delay fill system is and how to set it up. Without such knowledge the people in the way back of the concert will have a bad time. This past semester we spent a great amount of time in the school auditorium – a very helpful setting to explore the indoor side of the class. Two bands helped us through various sessions by performing while my students struggled but succeeded in achieving an enjoyable, clear sounding rather than an ear-bleeding sound.
I am very grateful to Los Babara and Funtastics, both renowned touring bands that where humble enough to help and share their talent with us. I did ask them to act a little snobby and demanding though, after all I am trying to expose my students to the time pressure of ‘the real world’. A few weeks into class I was trying to find an opportunity to set up an exterior show, a concert outside where my students could put what they had studied to the test. The head of audio suggested the building penthouse where the cafeteria is based. School officials approved this, meaning students could taste the contrast between both sound reinforcement worlds, inside and out. Their faces were priceless, they could not believe how different the two approaches were.
Their main struggle was the wind, and even with a powerful public address system the mix was not quite cutting through. More volume maybe the solution for some but our old friend the feedback loop jumped from time to time like an annoying goblin behind the speakers and floor monitors. “Find the feedback frequency and control it!,” I found my self shouting from time to time. Gradually the sound improved and students worked together taking on roles ranging from helping with the stage to taking turns in the FOH mixer. Once again Los Babara and Funtastics were there as our invited artists – the show was going ahead. However, in what will prove to be an unforgettable learning curve, students witnessed the ultimate crash and burn. One of my dearest students, who shall remain nameless, carelessly leant on the digital board, pressing the “recall” button while scene zero was selected. It resulted in the student recalling scene zero from the console´s memory – our whole routing mainframe was gone and went back to zero.
As nobody thought to save the console’s status to an available memory slot, all the work was gone. The band stopped playing and confusion reigned. A big mistake was made and everybody had a chance to learn from it. After all that is what the students were there for. However as the situation was critical I quickly helped to set everything back up as fast as possible. The band resumed the song, the faders went up quickly, the monitor sends were promptly set again. Everything that needed to be done was done as speedily as possible.
I will never forget this show, it reminded us all of the fears and risks a live engineer faces every show. It also showed how adrenaline-filled, difficult but ultimately gratifying this job can be. For some reason I get the feeling that my students will be hitting save every five seconds from now