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Sound System Engineering: an interview with Pat & Brenda Brown

Tom Kehr, Systems Designer and Trainer at Exertis Almo and host of the “Tech Tips” video series, leads and in-depth discussion with Pat and Brenda Brown of Synergetic Audio Concepts, regarding the Pro AV industry’s “identity crisis” and the importance of Synergetic Audio Concepts in audio-visual training.

Covering the various types of SAC educational courses, the history of audio engineering and training, recruiting new talent in the audio industry, and more, the video interview provides important insight into one of the most valuable training resources.

Tom Kehr
About the Author

Tom Kehr  

CTS-D, CTS-I, Network+, LEED Green Associate, ISF-C, ATD Master Trainer
In-House System Designer and Trainer
Supported Applications: System Design

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The Dreaded Gymacafatorium: 3 Keys to successful multi-use audio design

What is a Gyma-cafa-torium?

The “multipurpose space.” It’s the room that’s intended for everything but does not do any one thing well, and it’s the bane of audio system designers around the globe.

Your client has come to you asking for a sound reinforcement system in one of these “gymacafatoriums.” But first, let’s start with an etymology lesson:


💡 auditorium (n.):

“part of a public building where people gather to hear speeches, etc.,” 1727, from Latin auditorium “a lecture-room,” literally “place where something is heard,” in Medieval Latin, especially “a reception room in a monastery,” noun use of neuter of auditorius (adj.) “of or for hearing,” from auditus, past participle of audire “to hear.”

From this lengthy definition, it seems that being able to hear is pretty important.

Normally, we think of an auditorium as some sort of rectangular box with fixed seating and a stage or platform at one end, but if it’s a “place where something is heard,” the infamous gymacafatorium is really an auditorium, regardless of the sign placed above the entrance.

If people need to be able to communicate in a space, doesn’t that really make every space an auditorium, by definition? If you can’t hear the audio content, you’re not communicating.

3 Keys to Auditorium Audio Design

There are three components when making an auditorium function as a place where something is heard:

These are the physical and acoustical properties of the space. This involves the size, shape, and the absorptive, reflective, and transmissive properties of the floor, walls, ceiling, and any other materials in the space. Think of absorption, reflection, and transmission as a triangle. The sum of the degrees of a triangle always equals 180, and it is the same principle with sound energy in a space. If it’s not absorbed, it’s reflected. What’s not absorbed or reflected is transmitted into an adjoining space.

The shape of the space is also a consideration. Avoid domes and curved walls, as these will focus sound energy in undesirable ways.

If the space also functions as a gym, it’s typically a bigger room with a high ceiling. Normally, it will have hardwood floors, painted CMU (concrete masonry units or “cinder block”), and some sort of steel ceiling. The result is little in the way of energy absorption, thus providing for lots of reflective energy.  Even if they have wall pads, they aren’t of much help for absorption.

If it’s just a cafatorium, your ceilings may be 10 feet or so. These rooms typically have tile floors, painted CMU or gypsum walls, perhaps large windows, hopefully with acoustical drop tiles. Even with acoustically absorptive drop tiles, that’s absorption on only one of the six sides of the box, so these are typically noisy spaces as well. The low ceiling may limit you to using ceiling loudspeakers.

As the late John Murray still reminds us with Don Davis before him, “the only thing you can EQ is the loudspeaker.”  In other words, the electronic adjustments performed during the equalization process can only affect the response of the loudspeaker.  Once the sound leaves the loudspeaker, it’s out in the wild.  The room itself, the room acoustics, will imprint its signature on the sound before it arrives to the listener.  You can’t do anything about what happens to the sound between the loudspeaker and the listener unless you change the acoustical characteristics of the space.

Engaging a qualified acoustician at the beginning of any project of significance can help you design great sounding spaces. Many years ago, there were some commercials related to car maintenance that used the line, “Pay me now or pay me later.”  It’s also true of the acoustician.  The trouble here is that hiring the acoustician after everything has been built usually comes after a number of equipment upgrades that were intended to “fix the sound.”  Additionally, implementing acoustic treatments after building completion tends to be a whole lot more expensive.  Including the acoustician as part of the initial building design team can be a very economical decision.

All too often in the gymacafatorium, the HVAC system is way too noisy.  After all, it was designed to be a gym, right?  Reducing background noise levels to acceptable limits can be costly if the HVAC system requires a major refit or replacement to something that’s acceptable.  There are easy ways to measure the current background noise levels for an initial assessment.

ASHRAE, the American Society of Heating, Refrigeration, and Air-Conditioning Engineers, has a chapter in their reference works entitled Sound & Vibration.  It’s a great little chapter and includes Design Guidelines for HVAC-Related Background Sound in Rooms, and it provides RC (Room Criterion) numbers for various types of spaces.  If these guidelines were followed, a lot of spaces would be much more pleasing.

If you’re working in schools, a recommended resource is the ANSI/ASA S12.60 American National Standard Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools.  While I might prefer using RC or NC (Noise Criterion) numbers, it uses dB SPL.

hvac background noise

Loudspeaker selection and placement are critical here.  The methods range from modeling to well-educated estimates to some Homer employing a LAR (Looks About Right) approach.  Skilled sound practitioners typically have a pretty good handle on what works in a space, and they know it is not a one-size-fits-all world.

In a perfect world, large spaces should be modeled using various loudspeakers to see what make, model, and location directs the sound energy only where it’s needed and keeping it off of all unnecessary surfaces.  The outcome of modeling is that “this” particular loudspeaker(s) needs to be in “this location” and aimed in “this” direction.  Modeling is a prediction which leads to a more assured outcome.

If ceiling loudspeakers are the choice, various manufacturers have simple calculation programs that allow you to enter the space’s dimensions, loudspeaker model, tap wattage, and overlap pattern desired. The result is the number of loudspeakers, loudspeaker spacings, dB SPL level at the listener position, and even the total power amplifier wattage required for the space.

JBL ceiling mounted loudspeakers

Prioritize the Process and Get Support

Acoustics, background noise, and the loudspeakers. Note that I left the loudspeakers until last. All too often the thought process is all backwards, when number one priority should be getting the room right.

Regardless of where you are in the process as an integrator and working with your client, we have the support staff necessary that can assist with the best approach to meet your client’s needs.

Contact us today.

Tom Kehr

About the Author

Tom Kehr

CTS-D, CTS-I, Network+, LEED Green Associate, ISF-C, ATD Master Trainer

In-House System Designer and Trainer

Supported Applications: System Design

Did you find this blog post helpful? Engage with us over on LinkedIn.

Tech Tips with Tom Kehr | LG pt 2 – The Quick Differences

In part 2 of the Exertis Almo Tech Tips with LG video, Tom Kehr, Systems Designer & Trainer at Exertis Almo, and Dan Baker, Technical Business Development Manager at LG discuss savvy solutions for conference rooms, education, and work spaces.

43″ 3840 x 2160 One Quick Series LED Backlit LCD Large Format Monitors


LG’s 43HT3WJ-B is the all-in-one display for simple and quick video calls. With LG One:Quick Flex’s 43-inch all-in-one display complete with built-in camera, microphones and speakers, there’s no need to stress over online meetings and calls and no more inconvenience of connecting to and setting up video conferencing. Simplicity meets effective collaboration with touch and drawing. Equipped with In-Cell touch technology, the One:Quick Flex turns ideas into reality. With a dedicated touch pen, taking notes and drawing is easy. Work can be saved as files, and easily shared via mobile phone. On the move? This monitor is easy to transport with a movable stand. The One:Quick Flex can be used anywhere indoors where it can be moved by wheels.

Tom Kehr

Tom Kehr

CTS-D, CTS-I, Network+, LEED Green Associate, ISF-C, ATD Master Trainer

In-House System Designer and Trainer

Supported Applications: System Design

Tech Tips with Tom Kehr | LG pt 1 – How Quick? One:Quick

In Part 1 of Exertis Almo Tech Tips with LG video, Tom Kehr, Systems Designer & Trainer at Exertis Almo, and Dan Baker, Technical Business Development Manager at LG discuss how to achieve less hassles with all-in-one video conferencing solutions.

Less hassles with all-in-one video conferencing solutions from LG.

55″ 3840 x 2160 One Quick Series LED Backlit LCD Large Format Monitors


Video conferencing setup doesn’t need to be stressful. This all-in-one solution features a built-in Windows PC, crisp 4K UHD camera, microphone, speaker and a digital whiteboard. Experience clear video and sound qualities in your meetings.

Tom Kehr

Tom Kehr

CTS-D, CTS-I, Network+, LEED Green Associate, ISF-C, ATD Master Trainer

In-House System Designer and Trainer

Supported Applications: System Design

How to Buy a Car (or an Audiovisual System)

So, I need to upgrade my ride and decided that I need a 4WD, Crew Cab Dually, 1-Ton pickup with Leather interior and a towing package.  Budget is $10K.


Where did you get that dollar figure from?  40 years ago?  Someone is stuck in a time warp.  Audiovisual projects are often approached the same way – starting with an often unrealistic dollar figure.

I know someone familiar with a new House of Worship project with suggested donation amounts for some of the furniture and fixtures.  Big donation amounts.  This person asked me to guess what they budgeted for AV.  Because of how they phrased the question, I guessed a ridiculously low number.  “$20K”, I said.  Nope.  It was $15K.  Including installation.  I guess that’ll be a TV, a couple of hardwired mics and two powered loudspeakers.  At least they’ll be decent powered loudspeakers, I guess.

I had another recent request for a digital mixer with 24 mic inputs for “around $1000”.

All three of these scenarios have unrealistic expectations but only the first one is made up.

Here’s another real scenario with a different twist: “Will need a relatively quick turn-around – they are looking to move in within the next few weeks.”  Oh, and the drywall is going up in the next couple of weeks.  But it’s okay as I’m told the GC is putting in some access holes.  </sarcasm>

For this job, there’s no design, no Functional Scope, no Bill of Materials.  Nothing.  They’re not even sure what they’re trying to do yet.  The expectations here are also unrealistic as you won’t even be able to get all the equipment “within in the next few weeks” even if you ordered today.  And will any of those supposed access holes even be useful?  We have all been through this before.

I’m sure the furniture was picked out and ordered a long time ago – including any custom furniture.  Someone planned and ordered the phone system.  The Telecommunications Room was on the architectural floor plans from the beginning.  The fire alarm system certainly wasn’t a last-minute consideration.  “We move in in four weeks.  We probably need to get a quote on the fire alarm system we need.”  That sounds ridiculous, doesn’t it.?

Why is it then, that audiovisual is still clamoring to get recognition and a seat at the Big Kids’ Table?

Two things, in my opinion:

  1. I think we can only blame ourselves for the lack of perceived value that we bring to a project.  We’ve given away designs, worked nights, weekends, 2-3 days without sleep, fixed stuff that wasn’t our responsibility and given away time and equipment just to meet a deadline or make a client happy.  What other normal business does that to themselves?
  2. I’ve been around this industry for getting close to four decades and I think we’re great at promoting ourselves to ourselves but hardly anyone outside of our little AV Club knows we even exist.  For most of us, we have trouble defining “audiovisual” when someone asks us what we do.  We love our little Club, and we love the people we know in the Club but we need a serious outreach effort to technology decision makers and the other design teams that are part of every building project.  This one is a much deeper issue than I can write about here.  Unfortunately, I don’t see any real industry initiatives on the horizon.

What are some of the results of our industry’s apparent anonymity?  Lack of supporting infrastructure, washed out images, undersized images, projectors hanging in every incorrect orientation possible using caveman like engineering, unintelligible speech, and endless photos of horrendous AV integration examples on “AV Install Nightmares” and “Dodgy Technicians” on Facebook.  I have pictures of a downspout suspended horizontally in a room and used as a cable pathway.

And one of my favorites: Seeing the acoustical treatment deleted due to “value engineering”.

We know what good AV looks and sounds like but perhaps the regular users don’t because they haven’t been exposed to enough of it.  It seems mediocre to worse has been the standard.

It also doesn’t help when after the first client meeting, we come back with a Scope of Work and a quote and we’ve skipped the idea of working the client through their process and developing a Functional Scope.  In other words, a description of how the system works and what it does from the users’ point-of-view.

You’ve done it.  I’ve done it.  We sit in a room for the introductory meeting, and we have half the system designed in our heads before the client has finished talking.  We’ve been thinking about gear when we should be discovering the client’s workflow and discussing usability.

Back in 2001, Steve Thorburn wrote, “Our industry began as a ‘solutions’ industry.”  We seem to call everything a “solution” nowadays but we’re thinking “equipment” in our minds.

“Equipment” is easy.  You can get “equipment” at BigBox.  We need to get back to being problem solvers for our clients and then perhaps, we can avoid starting with dollars being defined first.

Let’s get back to being solutions oriented rather than equipment oriented. If we bring real solutions and not just boxes, I think we just night get a little more recognition.  And the start of any solution begins with understanding the client’s needs (not the gear you think they need).

If you’re not sure about how to conduct a true Needs Analysis so you can start your Solutions journey, join us at the Almo E4 in Anaheim on March 22 for our session specifically addressing Needs Analysis.  If you are not sure about how to turn your Needs Analysis into a real Solution, Almo Pro AV’s Engineering Services can help you there as well.

Tom Kehr, CTS-D, CTS-I, Network+, LEED Green Associate, ISF-C
Systems Designer and Trainer Professional Audio-Visual | Almo Corporation

[email protected]
888.420.2566 x6089

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