A New Tool for Sound System Training

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Few areas of audio have become more confusing than amplifier power ratings. We have developed a tool to remove the veil, revealing not only the power rating, but what it is based upon.

We’re now in our third decade at the helm of SynAudCon. During that time we have witnessed training technology advance from transparencies on overhead projectors to our current PC-based 4k presentation system. While the tools have become vastly more capable, the theory and principles passed to us from our predecessors have not changed. Truth is truth, and it is timeless. Words do not pass away, and I can still recall the gold nuggets of wisdom from the likes of Don Davis, Dr. Eugene Patronis, Neil Muncy and others that I received first hand decades ago. Our mission at SynAudCon is to preserve them and pass them on to a new generation of audio practitioners.

A Systems Approach

SynAudCon training covers the entire signal chain – all of the components required to reproduce sound. Don always emphasized that these are systems – individual components or stages optimized to work together to accomplish a task. A sound system is a chain that is limited by its weakest link. We have chosen to direct a large percentage of our training at the signal chain’s weakest links – room acoustics and electro-acoustics. When systems perform poorly, it is usually because of a challenging acoustic environment, poor loudspeaker selection and placement, or both. The vast majority of new and renovation sound system budgets do not include funding for acoustical changes to the space, so while our training shows how to diagnose and address these problems, the design process we present focuses on loudspeaker selection, placement, and tuning.

Loudspeaker Specifications

To achieve competency in this vital area in 2005 we developed a loudspeaker testing facility, focused at producing the spherical loudspeaker data needed for room modeling programs. We are proud to have been a part of the development of the Common Loudspeaker Format – CLF, a platform-independent format for loudspeaker specifications that is also a data format for PC-based room modeling programs. The objective of this venture was profit – not monetary but intellectual. The insights gained from creating a 3D measurement system from scratch and using it to test hundreds of loudspeakers from dozens of manufacturers has given us what we need to make SynAudCon training excel in this area, revealing both the strengths and weaknesses of the computer modeling process. We don’t just parrot what we read in books or articles. We present the essential principles from a perspective that can only come from learning the first principles, and doing so the hard way.

Amplifier Specifications

With loudspeaker testing conquered, our next objective was another weak link – audio power amplifier selection and deployment. Modern audio amplifiers are a truly amazing result of decades of research, engineering, and design. Our courses present not only how they work and how to best deploy them for a specific application. Unfortunately the marketplace has mostly simplified the amplifier into a power rating that is usually taken at face value. These give insufficient information about how an amplifier performs under various load conditions and can make amplifiers that are dramatically different appear to be the same. Can you imagine an electrician trying to do their job with only power ratings? They need to break down those ratings into voltage, current, and impedance to deploy utility power. Audio power amplifiers are far more complex than electrical wiring and it is incredulous to think that a one number rating tells the whole story.

First Principles

As with loudspeakers, to teach about amplifiers meant that we had to first learn about amplifiers. We had a proven example with CLF, whose existence has influenced SynAudCon training in immeasurable ways. The development of a Common Amplifier Format (CAF) would do the same for this link in the signal chain. What was needed were not new ways to measure amplifiers. That’s the job of Standards committees. CAF is a logical and consistent way to present those ratings to yield a complete picture of amplifier performance. We initially anticipated a few months of work. Five years in the CAF is now ready for use in SynAudCon in-person and online training. The last two years have been spent on writing CAFViewer, a freeware application that presents amplifier specs in the same way that the CLFViewer presents loudspeaker specs – everything needed, all in one place, and free to anyone who wants to use it. Like CLF it is brand-independent and versatile enough to be used by the entire audio industry, including professional, consumer, and automotive.

We’ve added a major addition to the SynAudCon website for the Common Amplifier Format. We want to make it easy for our trainees to access the information they need for our courses, and to give prospective trainees a sample of what to expect from SynAudCon training. The URL is

https://caf.prosoundtraining.com

Interactive Calculators

Power amplifier deployment requires some math. CAFViewer provides interactive calculators that make this part efficient and accurate. There’s no reason to leave the direct field SPL to chance. It all hinges on a handful of variables provided by the CLF, CAF and the system designer. There are calculators for both low and high impedance distribution systems, and both include wire gauge calculations. Most importantly, the calculators don’t just provide numbers. They present a logical thought process, helping the system designer think about and understand each step, homing in on a solution with their mouse wheel.

Power Ratings Un-masked

CAFViewer provides the traditional power ratings for amplifiers, but broken down into voltage, current, and impedance. The user will know why an amplifier is rated at “N” watts, and for several types of signals. Meaningful amplifier comparisons are now made simple. There’s even data for sizing utility power circuits and cooling systems. CAFViewer is concise and logical, shortening the time required to select an amplifier, not increasing it. Achieving greater accuracy in a shorter amount of time is what it’s all about.

Together CLF and CAF present a complete picture of amplifier and loudspeaker ratings. At SynAudCon we use them for training, but their potential uses go much further. We encourage you to visit the CAF website and download CAFViewer and some sample data. The calculators can be used stand-alone. The site includes some free training videos for anyone interested in digging deeper into amplifier theory. We are excited about integrating CAFViewer into SynAudCon training programs, as it will serve to make high level sound system training a more efficient process.  pb