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30 For 30: Lessons Learned From Years Of Tuning Sound Systems
A dartboard of 30 things I’ve learned in 30 years of being hyper-focused on one thing...
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loudspeaker world
The author at the Greek Theater in 1984 with a primordial (Meyer Sound) SIM rig. Bob notes that 30 years later, analyzers look different but he looks the same. (Photo credit: Clayton Call)

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  Loudspeaker World, Acoustic Measurement, Loudspeakers, Microphones, Best Practices, Bob Mccarthy

It was 1984 when I first sat in front of an FFT (Fast Fourier transform) analyzer during a concert and made decisions about tuning sound systems. I’ve been doing it ever since, and have written a lot of articles and a few books about this, but these are usually very focused and detailed.

This time I’ll go a completely different direction: a dartboard of 30 things I’ve learned in 30 years of being hyper-focused on one thing. No proofs or explanations. Just the ramblings of the old man of the FFT.

1) Make sure your analyzer is working right. The old saying “physician heal thyself” applies here. Be certain you have a working diagnostic tool before you say anything about the sound system.

2) Make sure the client knows what you can (and can’t) do. Make it the same is the big theme here.

3) Find out what can (and can’t) be done. Can the loudspeaker angles be adjusted? Can we break out the bottom box on its own DSP channel? Will this heritage hall allow us to cover the walls with fiberglass? Of course not! Can we hang the PA lower? You will never know if you don’t ask.

4) Don’t be a jerk. Be inclusive and collaborative. This is a team sport. Don’t embarrass or humiliate anyone. If possible, find a way to make everybody look good when major changes are needed. You can save the day after proving that the design or install is a total fail but you will never work in this town again if you humiliate the client while doing it.

5) Working with acousticians. They are experts in acoustics but don’t assume they understand sound system optimization. Their perspective doesn’t begin until the sound starts hitting the walls. It’s a statistical world of reflection paths, cavities and resonances. There is nothing statistical for us. It’s one-on–one relationships of speakers to particular surfaces. A statistically minor surface in exactly the wrong place is a huge deal for us.

Careful where you point that thing (the measurement mic).

6) Sound designers and mix engineers. These folks have great ears and an artistic vision. Listen closely to their wants and incorporate them into the tuning as much as possible. Let them know when they ask for the impossible so that a realistic plan can be put forward.

7) Get the stupid out of the system. Did the installer follow the plans? Is the loudspeaker path blocked? HF driver polarity reversal? Why is left side different from right?  There’s no glory in going through a thorough step-by-step verification, but plenty of shame in EQ’ing a loudspeaker that’s miswired. I would rather leave a system verified and untuned than tuned and unverified. Allow lots of extra time for tuning systems with external amplifiers. So many more opportunities for wiring errors, e.g., I found a 3-way system with LF amps driving the MF speakers (for seven years).

8) Quickly assess the physical. Time and resources are limited. Moving the array will take a big chunk, so figure out right away if that needs to happen. We can do front fills, surrounds, etc. while the main rig is down. Don’t wait on the physical stuff.

9) Keep it simple, stupid (K.I.S.S.).Take care of the big stuff and leave the fashion show for later. There are so many exotic tricks that can do amazing things at one location but very few that improve things for a wide area.

10) Advance planning. Have a flow chart, plan and section showing loudspeakers. Seating charts are nice for mic placement. Know how you will interface into the signal processing. Work with the designer to know how the subsystems are supposed to relate (e.g. the underbalcony feeds go with the center vocal system, not the L/R music).


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