Pat’s Blog – New GratisVolver Version


The freeware GratisVolver™ continues to be one of the most useful applications that I own. The ability to convolve impulse Zoom_H1responses 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 it 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

A great tool just got better. The previous version 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.

Calibration Support Added

The new GV adds calibrated RIR support. You can select the closest measurement as the reference, and the more distant measurements will be the correct relative level – great for showing how the direct field becomes swamped by reverberation with increasing distance from a source. The new version also adds some formatting options.

Thanks to Bengt-Inge Dalenback, author of CATT-Acoustic™ for this powerful freeware tool. You can download it from

Lastly, there’s a new Techny session coming out soon. It will include RIRs of some small-format line arrays and Don Keele’s powerful CBT array. All of the RIRs were produced using – wait for it – GratisVolver™. pb

GVolverFigure 1 – The new GratisVolver. Yes, that’s 80 dB+ of dynamic range for an RIR made from a recorded sweep!

Pat’s Blog – Prepping for Fall Specialty Seminars


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.

As the sun set, Brad and I dropped Steve at the airport, picked up the gear from last week’s Denver seminar, and hit a sports bar to talk more digital audio.

SynAudCon Digital – Nov. 16-18, 2015 in Washington DC



Making Wireless Work – New Staff Member and Some Tweaks

I’m loving this event, because I get to sit back and watch the presenters mold the presentations through conference calls and emails. This time around Eric Reese (Sennheiser) will join Tim Vear (Shure), Karl Winkler (Lectrosonics), and James Stoffo (Radio Active Designs) to round out the staff. James is bringing spectrum analyzers ranging from $300 – $30,000, and Tim Vear is bringing his faithful HP along with the new Tektronics RSA306. We’re going with two 12 ft projection screens and a roving wireless camera to give the attendees “eyes on” all of the demos.

These guys talk antennas like fishermen talk lures, and from listening in on their conference calls I can confirm that they really like this stuff. Someone needs to warn Las Vegas that the Tuscany Resort will be radio active in early December.   pb

Making Wireless Work – Losing the Wires Without losing your Mind
December 3-4, 2015 – Las Vegas, NV




System Integration Asia Covers SynAudCon Training

SynAudCon’s Training in Singapore received a nice write-up in Systems Integration Asia.

Check out page 24.

Pat’s Blog – 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


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

Pat’s Blog – A Forgotten Skill Set


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. tools

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.”

I recently performed some polar measurements on a loudspeaker array prototype. As part of the project I needed to isolate one of the small array transducers into a box of its own, a box which didn’t exist. It had to have exact external dimensions for the edge diffraction to be right, and it had to rotate about an exact point in space for the polar measurements. By the time an hour had passed, I had used a table saw, jig saw, electric drill (with Forstner bit), pneumatic nail gun, and band saw, along with a MIG welder, on some scrap materials that I harvested from the wood and metal shop bone yards. It was ugly and cost nothing, but it was exactly what I needed.

Modern audio practitioners have to know a lot of stuff – much more than previous generations. The time that could once be devoted solely to audio must now be divided between multiple technical fields, each of which could take a full-time effort to master. There’s only so much time, and becoming proficient with tools can get crowded out. There’s just no time. But is there?

Time is a resource, and it can be reallocated. My advice to the up-and-comers? Put down the smart phone, turn off the social media and the fantasy sports, and learn how to use tools. Browse the tool department at Home Depot and ask “What’s this for?” Buy some tools and start tinkering. Fix, repair, modify, destroy. Learn what makes stuff “tick.” Can you solder? Why not? Over time you will develop a skill set that will make you indispensable to your employer, or set you apart from your competition.

That app that we are staring at will soon be obsolete. The ability to use tools will never be.  pb


Pat’s Blog – A Simple HDMI Ground Loop Fix


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


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

SynAudCon Ice Cream Social Was a Big Hit

“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. Read more »

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. Read more »

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