Brenda’s thoughts on 2016

by Brenda Brown

Two thousand sixteen is quickly coming to an end.  I hope this means things are winding down so you can enjoy the holidays.  It is also a great time to reflect on the year with thanksgiving.

Pat & Brenda Brown, Don & Carolyn Davis

Pat and Brenda Brown, Don and Carolyn Davis 1996

In 1996, Don & Carolyn Davis provided us with a great privilege to continue their mission. Pat and I just celebrated our 20th anniversary at the helm of SynAudCon. I am often silenced with awe as I think about the last 20 years. Over the years, the computer has become a hand-held device, the world wide web has entered into our lives, we’ve seen the industry gradually change from analog to digital, and audio contractors have grown into integrators whose responsibilities now includes all facets of media.

As times changed, so has our approach to teaching.  We progressed from overheads, to video projection and now to online training.  A short video has replaced a chapter in a textbook. SynAudCon is teaching many of the same principles, but using modern delivery systems that shorten the learning curve of the student. (more…)

Hemispherical Loudspeaker Balloon Data Using an 1/2-space Mic Array


Pat Brown shows a technique for collecting fast, accurate hemispherical loudspeaker balloon data.

I frequently get requests to measure hemispherical loudspeaker balloon data for ceiling and wall-mount loudspeakers. This information must be collected in half-space, so in 2016 I built a mic array for this purpose.

The array consists of 19 microphones at 5 degree angular resolution. The concrete floor was excavated to house a 1 x 1 x 1 meter stainless steel-lined “pit” that houses a motor-driven turntable (LinearX LT360).

The rig allows the measurement of boundary-loaded loudspeakers with any acoustic symmetry – polar, 1/4, 1/2, or none at a 2 meter microphone distance. The time window of 60 ms provides a frequency resolution to about 50 Hz.   (more…)

How Sound Behaves As It Hits Different Types of Surfaces

by Brenda Brown

Acoustics First® produced three video simulations to help us visualize how sound behaves as it hits different types of surfaces.

Many of us enjoy spending time with our family over the holidays. I come from a large family so we usually have 30 (10 are under the age of 8) at our Thanksgiving dinner. This year it was held at my sister’s home who has the typical open-space floor plan with hardwood floors. This look is often seen in the newer homes.  The noise level was almost unbearable at times.

Being married to Pat Brown, we have acoustical treatment on the walls, ceiling and carpet on the living room floor.  Our kitchen has hardwood floors but the living room and kitchen are in separate rooms. The experience is totally different. Our space is so much more enjoyable.

We all love instructional videos.  With the use of videos, we can understand things in a few seconds that once took a long chapter of text. Acoustics First® has produced three video simulations to help us visualize how sound behaves as it hits different types of surfaces and why our space is so good and my sister’s space is not. (more…)

SynAudCon’s ECS: Design and Deployment Seminar

by Brenda Brown

Highlights from the ECS: Design and Deployment seminar.

SynAudCon was in Washington DC last week presenting our ECS: Design and Deployment Seminar.  It was neat being in a historical city during an historical election.  Those who attended the seminar are now aware of historical changes within our industry.

For 43 years, SynAudCon has been offering one-time events as new technologies develop so we can get our attendees up-to-speed quickly.  Of all the one-time special events offered in the last 43 years, this event presented the greatest opportunity for sound system practitioners.

Wayne Moore, Larry Rietz and Bill Nattress presented the new code changes – where it is going and ways to work with the Authority Having Jurisdiction, or AHJ. They presented cases where pro audio systems are now being used for ECS announcements.  Their passion to save more lives through use of the house sound system was clear in their presentations. (more…)

What are the Differences Between Analog and Digital Interfaces?

by Pat Brown

Pat Brown will help you understand the pro and cons of analog vs. digital interfaces.

Are you new to digital audio? Are you confused by the landscape of formats that have emerged in the marketplace? Following is a short expose that may shine some light on this potentially confusing topic.

Inputs and Outputs

It’s all about inputs and outputs (I/O). How do I get an audio signal from one to the other? The ongoing evolution of professional audio has produced a number of viable digital interfaces to complement legacy analog I/O practices. The choices may seem confusing at first, but when you break them down the strengths and weakness of each become apparent.

In this overview, I will start with analog since it is familiar to most readers and serves as a reference for the discussion of digital formats. I will focus on professional interfaces only. While similar in many ways to consumer I/O, professional are more robust against electromagnetic interference (EMI) and allow much longer cables – both requisites for large sound systems. (more…)

Sound Reinforcement Solutions for Emergency Communication Systems

Emergency Communication Systems Icon

Why AV Integrators Should Be Involved in MNEC Solutions

The topics of Mass Notification and Emergency Communications (MNEC) initially conjures us mental images of a smoky room illuminated by flashing strobes. A barely intelligible message from a 4-inch loudspeaker attempts to cut through the din and deliver life-or-death instructions to the building’s occupants. Fortunately, this often works, and lives are saved.

A major problem is that this mode of message broadcasting does not scale with room size. This results in large, noisy, reverberant spaces being served by the same limited-fidelity strobe loudspeakers as the small, dead office environment. The intuitive “fix” is to do what a lighting designer would do to achieve more illumination for a dark room – just add more fixtures. Unfortunately, sound isn’t light, and adding more loudspeakers can actually reduce the intelligibility of the emergency messages. The MNEC community has learned the hard way that a broader pallet of tools and different type of expertise are required to deliver MNEC messages in large spaces. (more…)

Do I Need “Digital” Audio Cable for a Digital Audio Interface?

by Pat Brown

What is a Digital Audio Cable?

The audio interface provides the means of getting the signal from one component to the next. It includes the source (output) circuit, the cable, and the load (input) circuit. There are consumer (2-wire, unbalanced) and professional (3-wire, balanced) versions, the major difference being robustness against electromagnetic interference in its various forms (Fig. 1). Does a digital audio interface require a digital audio cable?

Bal-Unbal-Interface and digital audio cable

Figure 1 – Unbalanced and balanced audio interfaces.

Since increasing the cable length can have a detrimental affect on both analog and digital audio signals, the use of balanced interfaces is mandated for large room systems. A cable contains multiple wires, or conductors. A cable designed for an unbalanced interface has a two conductors, one of which is a shield. A cable designed for a balanced interface has three conductors consisting of a twisted-pair and shield (STP). For this reason, the cable itself may be referred to as unbalanced or balanced. I’ll limit this article to a discussion of balanced interfaces and cables.

Do balanced analog and digital interfaces require different cables? I will first lay some groundwork. (more…)

Amplicalc – Free Power Amplifier Calculator by SynAudCon

Practical_Audio_Header - Power Amplifier Calculator blog





Amplicalc is a free “power amplifier calculator” developed by SynAudCon. This useful tool will help you select the proper amplifier. Video tutorial is included.

As simple as audio power amplifiers seem to be on the surface, selecting one for a loudspeaker is tricky. This is partly due to the completely different criteria used to establish amplifier power ratings vs. loudspeaker power ratings. The former is a measure of production. The latter is a measure of endurance. Our power amplifier calculator freeware AmpliCalc™ helps remove the mystery.

A new version of AmpliCalc allows you to select the amplifier’s sine wave rating, and then determine the RMS voltage (and continuous power) delivered to the loudspeaker by considering the signal’s crest factor.

Now, the user can work the problem the other way, starting with the loudspeaker’s power rating, and then determining the required amplifier sine wave rating based on the crest factor. Either way, AmpliCalc takes the mystery out of audio power amplifier sizing.

You can download AmpliCalc here.

The video below gives an overview of the new features.   pb (more…)

Ten “70 V System” Myths


“70 V Systems” Needn’t Be Confusing

Of all the topics covered in SynAudCon courses, few are as misunderstood as “70 V” systems. Most people are surprised to find that these systems share many common traits as “direct” connected systems. The most important trait of these systems is the use of transformers on the loudspeakers (usually internal) to “step down” the signal voltage before applying it to the loudspeaker. This is necessary because the signal voltage is “stepped up” at the amplifier. In fact, at SynAudCon we prefer the term “transformer distribution system,” especially since they can be based on voltages other than 70 V.

The ratings and specifications are based on sine waves, but any audio signal can be played over the system.


Ten Reasons Why Church Sound Systems Cost More


In a day of mail order mania and cost consciousness, remind your church sound customers of some basic truths

by Pat Brown

A letter to a church sound committee might read:

Thank you again for the opportunity to provide you with a proposal for the sound system for your house of worship. While we appreciate your interest in “good stewardship” in the funding of this project, and understand your request for “church pricing” for the work, the following points should be kept in mind when determining the best value for the dollars spent. (more…)

Pat’s Blog – New Learning Resources

Practical audio resources

Educational Resources For Audio Professionals

Here are some new web resources to help you continue your self-education at the time and place of your choosing.

Filter Hose v2
First, there is a new version of a powerful FIR development tool – Filter Hose. FH is a FIR toolbox for audio practitioners. It accepts input data in many forms, and allows you to sculpt a FIR filter to meet your needs. It is low cost, and a light version will be available soon. The tutorial videos on the HX Audio Lab website are great learning tools. I mention it here because FH is platform-independent and works with data from virtually any measurement system.


On-Site RIR Survey


Site Survey: Room Impulse Response (RIR)

Preparations for this fall’s Making Wireless Work seminar are underway. Our members wanted an east coast event. Based on recommendations from the seminar staff and others, the site is Newark, NJ. There is a major airport nearby, local mass transit, and good access from the East coast rail system.

We were in Newark last month conducting Sound Reinforcement for Technicians and took the opportunity to do an informal site survey of the hotel and area. So, how much info can you get, armed with only an iPhone?

The Area
Below is a photo of the area. The Robert Treat hotel is just to the left of the blue sign. This is the seminar site. The New Jersey Performing Arts Center (NJPAC) is just to the right of the sign. (more…)

Directivity Reference for System Design

by Pat Brown

The key to working in the field of audio and acoustics is to understand the need to establish a reference condition. This allows changes to be assessed objectively. You need a “known” in order to determine unknowns.

An effective site survey is driven by getting the most information in the least amount of time and with the least amount of gear. If one is clever, they can acquire a meaningful set of room data, with very little site time. That’s important, because there’s never enough time. (more…)

Need a Patch Cable Quick?

hook up wire how to

Quick Patch Cables for Around the Shop

It’s a recurring story. You need a point-to-point patch cable to temporarily connect Product A to Product B, but you don’t have one with the correct connectors. If these are professional audio products the inputs and outputs should be balanced. This means that only a twisted-pair is required to make the connection. Sure, you have spools of “mic cable” (shielded twisted-pair) but dealing with the outer jacket and shield takes time. You can get hooked up much faster by making your own twisted-pair patch cable from hook-up wire. (more…)

So…Wiki is not Lucy’s husband???

By Jim Sorensen
This use of unsupported sources happens all the time, particularly in the media itself.  How often have you heard someone on TV say that the bloggers are reporting such and so?  Bloggers?  What the heck is a blogger and why does a bloggers opinion count more than mine? (more…)

War Tuba

A brief explanation of a War Tuba.

First impression this photo of a War Tuba looks like a loudspeaker. It is actually a mic.

Acoustic location devices were used by military services from mid-World War I to the early years of World War II for the passive detection of approaching enemy aircraft by listening for the noise of their engines. These typically consisted of large acoustic horns attached to stethoscope-type earphones worn by monitors. This technology was rendered obsolete before and during World War II by the introduction of radar, which was far more effective.

Photo of a War Tuba



Analog or Digital?

by Tim Hamilton

Through most of audio history, it has been an analog world. Recently, it has changed to digital. Does that mean analog is dead?

I love new gadgets and toys.  Whether it’s an audio gadget, computer toy, phone accessory, or some new electrical product, I will likely think it’s fun and exciting to play with.  As a frequent early tech adopter, it’s not uncommon for my wife to roll her eyes and graciously smile while I tear open the box of some new, recently arrived electronic gadget and then disappear to go try it out.  Admit it – most of us in the audio industry can identify with looking for the next great widget.  Of course, the world of audio has quite a few new “toys” that get released every quarter and digital mixing consoles in particular offer a plethora of new things to play with.

For much of the short history of the audio industry it has been an analog world.  But now the industry has shifted into a digital world, which means that we now have all sorts of “digital” devices we can use in audio systems (i.e., processors, mixers, microphones, etc.). But, just because we have new digital toys to play with, does this mean that analog is dead? (more…)

SynAudCon Seminars taught regularly in Australia/NZ

SynAudCon is bringing their in-person seminars to Australia and New Zealand under a new arrangement with local AV training provider Technication.  Acting as SynAudCon’s local agent, Matt Vance from Technication will deliver the seminars, commencing April 2016.


Matt Vance

The first to be offered will be the 2-day Core Principles of Audio seminar, covering the essential theory of audio and focusing on what a practitioner needs to know to effectively deploy and operate a sound system.

“SynAudCon is extremely pleased to be working with Matthew Vance at Technication. We have enjoyed watching his progress with Technication and are confident that he will represent SynAudCon well.  We are absolutely delighted that SynAudCon’s “Core Principles of Audio” seminar will be taught regularly in Australia and New Zealand.” Pat and Brenda Brown – SynAudCon

Independent education for audio professionals has been difficult to come by in Australia and New Zealand, and it has always been a challenge to bring SynAudCon seminars all the way from the US. Despite the distance, SynAudCon is known in Australia and New Zealand for providing comprehensive and relevant audio education, so working with a local business that is also passionate about education is a natural fit.

“Attending a SynAudCon seminar in 2013 was a lightbulb moment – allowing me to see first-hand how complex audio concepts can be made understandable in an easily accessible way. Technication has given me the perfect vehicle to bring their unique approach to Australia and New Zealand, and I’m excited to be able to offer SynAudCon’s renowned quality, independent audio training to my peers in our local industry.” Matt Vance – Technication

The “Core Principles of Audio” seminar is approved for 16 Infocomm CTS Renewal Units, and will be held in most Australian and New Zealand capital cities from April 2016.

Here’s the dates of the first three seminars.

  • May 3-4, 2016 – Melbourne, VIC
  • May 10-11, 2016 – Sydney, NSW
  • May 17-18, 2016 – Auckland, NZ

Room Modeling Workflow


Room Modeling Workflow

by Pat Brown

An alternative title for this blog could be “How a Balloon Pop Can Save the Day” for a sound system designer. When building room models for acoustics simulation, the order of workflow is important. The intuitive order for room modeling workflow is:

  • 1. Build wireframe
  • 2. Assign absorption (ABS)
  • 3. Calculate reverb time (RT)

Logical, but it can lead to some huge errors. If a surface material has a low alpha, such as concrete, and it covers a large area, a small error in the coefficient will lead to a huge error in the RT.

An Example
On a recent project, a parking garage, the calculated reverb time of the space was over 9 seconds, using the “default” concrete coefficients and the Sabine equation. Measurements in the space revealed the actual RT to be just over 2 seconds. This illustrates some of the problems with statistical reverberation equations, which is that they are fickle and conditional. The parking garage, with its low ceiling, does not have a “mixing” geometry. The ABS coefficients for concrete are not correct for this scenario, and since there is so much of it a small discrepancy produces a very large error. (more…)

Take a Step Back in time to the Brussels World’s Fair 1958

Don and Carolyn Davis exhibit their HiFi system at Brussels World’s Fair in 1958

Take a step back in time to 1958.  Don & Carolyn Davis (SynAudCon founders), William H. Bell and George Petry were selected to exhibit their HiFi system at Brussels World’s Fair.   For 10 days, they staged demonstrations every 30 minutes drawing crowds which probably totaled 50,000.

What a neat article.

Newspaper article of Brussels World's Fair in 1958Brussels-News 6


Multi-channel Sound Was Designed for the Middle Seat


Multi-Channel Sound and the Middle Seat

I don’t see movies in theaters often, but when I do, I want a good seat to experience the multi-channel sound system. This means getting there 30 minutes early to get a seat along the center line of the theater, usually about half-way back. This provides the best stereo image and mix of the surround channels. Theaters are all about multi-channel sound, but you need to be in the best place to experience it.

Lessons from the “Ancients”

Ironically, multi-channel sound is not a modern invention. It’s creation can be traced back to the early 20th century, specifically the era of “making movies talk.” Bell Labs conducted exhaustive experiments at the time to determine the best way to emulate the live listening experience for someone sitting in a theater. This research resulted in a 3 channel playback system – Left, Center, Right. Each reproduced a unique mix of the sound sources, pulling the observer’s attention to any point on the stage. The rise of home theater in the 1990’s brought the theater experience into the living room, and production studios produced “surround sound” sound tracks for their films. While most home theater receivers allow the center channel program material to be mixed equally to the left and right loudspeakers (this produces the proper localization for someone sitting equidistant from them), the Left-Center-Right system is still the best way to experience a movie. The rear channels provide sound effects and create the sensation of spaciousness, but the dialog is carried by the front channels (mostly the center channel), so that the sound appears to be coming from the moving lips on the screen.

One Man’s Treasure…

Last week we were in south Florida for a short vacation, and decided to see a movie. It was an impulsive decision and we walked into the theater without my requisite 30-minute lead time. Middle Seat Listener GraphicI was certain that the “sweet spot” was already taken. To my amazement, the center seats were the only seats left. The aisles were completely lined with senior citizens, there for the matinee. I approached an elderly lady at the end of the aisle, and said “Excuse me, but can we get through?” She replied, “Sure. It’s a shame that someone has to take those middle seats!”

So, while the middle seat may be a curse on an airplane, it’s the best spot in a movie theater. Just don’t tell the seniors.  pb


Digital Signal Processors (DSP): Comparison Revisited

Digital Signal Processors (DSP) and IIR Filters

Digital Signal Processors (DSP) and IIR Filters

It’s been about 5 years since I published a couple of articles on the differences between Digital Signal Processors (DSP). You can find those articles on the SynAudCon website. I had to revisit the topic on a recent loudspeaker measurement project.

The back story is that a loudspeaker manufacturer sent me a two-way loudspeaker for testing, along with the required settings (IIR filters) for the Digital Signal Processor. The resultant response did not look as expected, so we investigated and found the DSP to be the culprit. I had the manufacturer send me a measured IR of their Digital Signal Processor, and I compared the  frequency response magnitude to two DSPs that I have in the measurement rack. Figure one shows the comparison.

Digital Signal Processors (DSP) and IIR Filters

Figure 1 – A comparison of three popular DSPs with the same settings. Click to enlarge.


Why Reverberation Formulas Don’t Work


Reverberation Formulas: Assessing Room Types

It’s been over 100 years since Wallace Clement Sabine sculpted his famous reverberation formula for estimating the room reverberation time from a handful of variables that include the room volume, surface area, and the “alpha” of the material covering each surface area – the so-called absorption coefficient. Multiplying the alpha by the surface area yields the Sabins of absorption. His formula worked well for the space in which he derived it – the Fogg Lecture Hall at Harvard University.

T = (V/Sa)0.161


T = Reverberation time for 60 dB of decay

V = Volume

S = Surface Area

a = absorption coefficient

While the formula established Sabine as the “father of architectural acoustics,” the formula was quickly found to be quite conditional. The accuracy varies wildly with rooms of different volumes, shapes, and Sabin content. Modified versions were produced by Eyring, Fitzroy, and others, but the take-away is that RT formulas provide estimates, at best. Recommended further reading is Leo Baranek’s scholarly paper on the subject. (more…)

New GratisVolver Software Version

GratisVolver Software

GratisVolver Software: New Release

The freeware GratisVolver™ continues to be one of the most useful applications that I own. The ability to convolve impulse GratisVolver Softwareresponses with anechoic program material let’s me sit at the mic position and listen to what a room measurement sounds like in the comfort of my office. It is also a powerful tool for producing the room impulse response (RIR) from a sweep recording. I used GratisVolver Software to produce the RIRs for our “Techny sessions,” which are among our top downloads ever. I’ve written much about this technique in the past. Here’s a link for our members.

The Need for Proper Relative Levels

GratisVolver Software is a great tool just got better. The previous version of GratisVolver Software always normalized the RIR to full scale. That’s pretty standard practice and not a problem when looking at a single measurement. But, I usually make log-spaced measurements that I want to compare later. At Techny I use 20, 40, and 80 ft. When these are normalized to 0 dBFS, the reverberant field level gets louder with increasing distance from the source and the direct field stays the same level. That’s just the opposite of what happens in a real room. I’ve always been able to mentally ignore this, but I no longer have to with GratisVolver Software. (more…)

Prepping for Fall Seminar: Making Wireless Work

Making Wireless Work: 2015

Making Wireless Work: 2015

Things are buzzing at SynAudCon this week, and it’s not a ground loop. Preparations are under way for two upcoming specialty seminars – SynAudCon Digital and Making Wireless Work.

SynAudCon Digital – Better Than Ever

Steve Macatee and Brad Benn flew in on Monday for a couple of days of prep.

We devoted the first day to manual revisions. Topics were added. Topics were removed. We re-balance the content of this seminar each time we have it, as dictated by new developments in the marketplace and feedback from the previous event. New demos were added for dither and noise-shaping. We capped the day with some Thai food in a local country town, talking digital the whole time.

On day two, we went through the hands-on workstations, with about half the day spent on firmware updates. The workstations include our new Cisco managed switches for computer exercises. Since last time we’ve added some fiber links using mini-GBICs on the switches. The Audio-over-Ethernet exercises include Dante-enabled products from eight different manufacturers. They’re apples, oranges, and pears, and attendees will get a good exposure to a variety of interfaces as they cycle through the workstations. We’re going to make it work, break it, and then make it work again, merging the eight workstations into a single system as the final exercise of the seminar. (more…)

How to Choose Pre/Post Service Music

By Curt Taipale

Curt Taipale addresses the question, “What music do you play before and after the worship service?”

I hear this question asked often. “What music do you play before and after the worship service?”

Curt Taipale

Curt Taipale

I might as well make you feel bad right from the start. The best choice of music to play is NOT your favorite Christian CD, not that new cool song that you want everyone to hear, not what is the most requested artist on the local Christian radio station, or anything of the sort.

Nope. You actually have to think this through. Why do we want music playing in the background as people are assembling before the service? And why do we want music playing in the background after the service as people start to leave? And how long should the music play anyway?

It may be that the best music to play before and after the service is no music at all. Why? Watch the crowd. What are they doing? Longtime members of your church are most likely engaged in visiting with their friends and people sitting nearby. They long for that ever so brief moment to interact and catch up on the past week’s events. After the service they may be praying for one another, or inviting them to lunch that afternoon, or setting a time to meet later in the week, and so on. (more…)

Pat’s Blog – Keele Tone-Burst Test

Keele Tone-Burst Test

Keele Tone-Burst Test

The Chicago, IL Sound Reinforcement for Technicians seminar has come and gone. One of the highlights was an evening presentation by DB Keele, Jr. Many of you know Don from his work at Electro-voice and Harman, and for his patents on Constant Directivity (CD) horns and Constant Beamwidth Transducer (CBT) arrays. One of his numerous other accomplishments is the development of a test for the short-term power handling of loudspeakers. This was the subject of his evening presentation.

The “boink” test uses a 6.5 cycle wavelet to pulse a loudspeaker. It is performed at 1/3-octave intervals. The stimulus itself is 1/3-oct in bandwidth due to its length. There is an article with more detail in the SynAudCon Member Library. The WAV files were included on the SynAudCon Test CD for Sound Reinforcement Systems. It is long out of production, but you can download the files below. The files are stereo, with the bursts repeating at 1-second intervals in the left track and 2-second intervals in the right track.

Just download (2 MB) and unzip to a directory of your choice.   pb

Keele Tone-Burst WAV Files

Keele Tone-Burst Test

DB Keele, Jr. tests my “snowman” demo 3-way loudspeaker. 

Pat’s Blog – A Forgotten Skill Set

Utilizing Low-tech Tools in a High-tech World

Utilizing Low-tech Tools in a High-tech World

These days we all spend a lot of time looking at computers. In today’s connected, app-driven world, there can be little time for anything else. A skill set that is fading into the sunset is the ability to work with tools.

The previous generation had a different experience. Sound companies once carved their place in the market by their ability to fabricate. Visit a loudspeaker designer and you would find a fully-equipped wood and metal shop for hammering out ideas. Without the ability to fabricate, a sound contractor was at a great disadvantage. If they couldn’t source a part, they had to make it – sometimes on-site. Utilizing Low-tech Tools in a High-tech World

When my son went off to college in the early 2000’s, he was immediately designated the handyman for his frat house because “None of the other guys knew how to use tools.”

With audio practitioners, it can be advantageous in many ways when utilizing low-tech tools in a high-tech world…


Ground Loop Fix: GenFen TV Wireless RF

Simple HDMI Ground Loop Fix

Ground Loop Fix: GenFen TV Wireless RF

We recently held SynAudCon seminars in Singapore, Bangkok, and Shenzhen (China). I brought along my usual case of audio gear, and each venue provided a house AV system. The evolution of the PC – in my case, a MacBook running Win7 under Boot Camp – has pushed me into using HDMI for my video output. The up side is the small connector and cabling size, which is nice for travel, along with being able to carry my own ultra portable HDMI switcher. The down side is that mixing consumer and pro interfaces can result in grounding issues.

My usual process is to setup my tabletop of gear, and then make the final connections to the house AV system. In all three venues, these final connections produced a significant hum and buzz through the house PA. In each case, disconnecting the HDMI video feed killed the hum. We went through the usual litany of “remedies” to get through the events, changing some things that shouldn’t matter in a fully pro audio system until it worked. Remember, HDMI is a consumer format and sticking into a sound system can produce grounding issues. This was a self-inflicted wound, and the price paid for the benefits of HDMI.

The ultimate fix? Another upside of HDMI is the availability of small, low-cost, RF links. The wireless HDMI link that I use in my domestic system would have solved the problem in each venue. It will now live in my travel case as a must-have for presentations on-the-road. pb

Simple HDMI Ground Loop Fix

SynAudCon Takes Their Audio Training Abroad

Pat and I are enjoying taking our training outside of US borders. In 2015, we have given training in China (twice), Brazil, Singapore and Thailand. We are very thankful to the below companies for making this possible. It takes the cooperation of a lot of people. Needless to say, it has been a very interesting and rewarding experience.

The total attendance between of the five seminars was 560. The attendees were very motivated learners. They welcomed us graciously and they were grateful for the training. We received several requests to return in 2016.

Enjoy the class photos of each seminar.

366C8183 - Version 2

Sound System Design – March 18-20, 2015 Shenzhen China


Line Array Theory and Deployment - May 25-26, 2015 AES Brazil

Line Array Theory and Deployment – May 25-26, 2015 AES Brazil

Principles of Sound System Design - August 20-21, 2015 Singapore

Principles of Sound System Design – August 20-21, 2015 Singapore

Sound System Design - Aug. 24-26, 2015 Bangkok Thailand

Sound System Design – Aug. 24-26, 2015 Bangkok Thailand

OptEQ - August 31-Sept 1, 2015   Shenzhen China

OptEQ – August 31-Sept 1, 2015 Shenzhen China

DIY Microphone Shield / Gobo

Acoustics First shows a clever way to make a DIY Microphone Shield / Gobo.

Acoustics First understands that the Do-it-Yourself spirit in the audio world is alive and well. Here is another one of our contributions to that community  – DIY Microphone Shield / Gobo .

Photos showing the supplies needed to make a GoboThe personal mic shield… all you need is…

  • Foam safe Glue
  • a One inch thick, three ring binder
  • two 1 foot x 1 foot pieces of foam
  • 2 Minutes

Got everything together?
Do you have 2 minutes?
Let’s do this! (more…)

SynAudCon Ice Cream Social Was a Big Hit

A brief overview of SynAudCon Ice Cream Social.

“Standing room only” is how I would describe the SynAudCon Ice Cream social. Pat and I were so grateful to see such a nice response.

We would like to thank everyone for attending. It was a very special evening.

I received this thank you note from Phil Cartier. I think he summed the evening up quite nicely.

“Thank you so much for a very enjoyable evening at InfoComm. As always, the conversation was stimulating and seeing the old friends and the new list-serve posters was great fun.”

I would like to share some photos that were taken at the event. (more…)

Sound Masking

Here are ten useful articles on Sound Masking.

Learn about how Sound Masking can help improve productivity and protect speech privacy in the workplace.

Learn about how Sound Masking can help healthcare facilities improve patient satisfaction and HCAHPS scores.

Learn about how Sound Masking can help reduce distractions while improving acoustics in call center environments.

Learn how Sound Masking can reduce financial firms’ risk of negligent disclosure of client information.

Sound masking is the addition of a familiar sounding, air conditioning-like background sound to an environment.

Eight simple recommendations for good acoustical etiquette in an open office plan.

Acoustical comfort is an important goal of modern office design. But what factors actually contribute to the perception of acoustical comfort?

Optimum masking sound: white or pink?

One of the most common concerns with demising wall constructions involve the resulting acoustical privacy between the two spaces. Fortunately, a metric known as the Speech Privacy Potential (SPP) has been developed to answer this question quickly and easily.

Unique performance advantages of a Qt® Quiet Technology™ sound masking system.

SynAudCon’s Ice Cream Social at InfoComm

SynAudCon will have an Ice Cream Social at InfoComm.

  • Date: Wednesday, June 17th
  • Time: 5 – 7 pm
  • Location: Upstairs at the Convention Center in classroom W312A

Stop in to enjoy an Ice Cream Sundae and to say hello to everyone.

Please RSVP to Brenda at by June 8th.

We hope to see you there.

Pat and Brenda Brown

Audio Veterans Shared at a SynAudCon Seminar

On March 9-11, 2015, forty-two AV practitioners attended the Sound System Design seminar in Atlanta, GA. The first day of the seminar was spent on measuring and interpreting the room impulse response – RIR. Day 2 is spent on electro-acoustics, primarily loudspeaker directivity and coverage, along with amplifier-sizing. Day 3 “puts it all together” and demonstrates the efficient use of computer modeling for designing systems with high speech intelligibility and music clarity.

IMG_0016Atlanta is city filled with audio veterans. On the first night of the seminar, SynAudCon provided dinner for the seminar attendees and invited several of the local audio giants to share with the group. The guests included Dr. Eugene Patronis, Bill Thrasher Sr., Wayne Lee, Chris Hamlin, and several from Danley Sound Labs. (more…)

SynAudCon Presents in Shenzhen China

In March 2015, eighty sound system designers came together in Shenzhen China to take SynAudCon’s 3-day Sound System Design seminar. The seminar was hosted by EZPro International, a distributor for Community Professional, EAW, Mackie, Symetrix and 15 others brands.

Pat Brown and Tao Zhang

Pat Brown and Tao Zhang

Tao Zhang, VP of EZPro International, approached us to present in China a few months ago. Tao lived in the United States for several years. During that time worked for Community Professional and  attended several of our seminars. In 2013, Tao moved back to China. He soon became aware of the their need for audio education. (more…)

Tall Microphone Stands for System Tuning

by Pat Brown

Pat Brown show how he uses tall microphone stands for system tuning.

One of the most valuable tools for sound system tuning is a tall microphone stand. This allows you to get the measurement microphone away from the seating plane. Why?

The Floor-Bounce Effect – FBE

The first reflection to show up on the measured impulse response of a loudspeaker is usually the reflection from the floor. This produces comb filtering in the measured response that is position-dependent over the listening plane (Fig. 1). See my article from 2011 for some measurements.


Figure 1 – The Floor-Bounce Effect (more…)