Target SPL and Required Amplifier Size

In a previous article (Loudspeaker Sensitivity: What’s a Watt Anyway? April 2010 Voice Coil), I examined the topic of loudspeaker sensitivity and how it may or may not relate to the overall sound pressure level (SPL) produced by a loudspeaker. The output capability of the amplifier driving the loudspeaker is of equal importance to achieving the target SPL from the direct field of a loudspeaker. This can also be related to the driving signal or the intended program material. This article was originally published in Voice Coil, May 2010.

In this reference article, published by audioXpress in 2008, Joe D’Appolito shares his experiments with loudspeaker evaluation. In the two parts of this article, D’Appolito tries to answer the question: “Of all the measurements available to the designer, which ones are the best predictors of listener preference?" In over 30 years of designing loudspeakers, I have found the following measurements taken as a group provide the strongest predictor of loudspeaker preference available to us today,” he states.

The controversy over subjective versus objective loudspeaker evaluation has raged on for decades. However, to my mind, there is no controversy. These criteria are simply two faces of the same coin. In over 30 years of designing loudspeakers, I have found the following measurements taken as a group provide the strongest predictor of loudspeaker preference available to us today. Want to know more? Read this reference article, originally published in audioXpress, September 2008.

This Spotlight reference article details a simple and fast procedure for testing the diaphragm used in microspeakers, headphones, tweeters, and microphones. Meaningful information comparable to Stiffness KMS and Mechanical Resistance RMS of the Thiele-Small (T-S) parameters is the basis for tuning the production process and for communication between transducer manufacturers and soft parts suppliers. This article was originally published in Voice Coil, January 2016.

Setup tables are OK, and alignment protractors have their place. But there comes a time when a vinyl hound can’t quite abide them anymore. Maybe you’re working on an 80s-era direct drive table and find the factory setup is suspect or even way off. Maybe you’re an archivist setting up a spare unit for 45s or 78s. The fundamentals are easy, or rather, they are once you look at them from the proper perspective. This article was originally published in audioXpress, April 2011.

Loudspeaker design is not a trivial exercise, and as a result, high-performance acoustic simulation software is essential to get accurate predictions that help an engineer develop superior products. Demand for simulations at early design stages are increasing because cost and timing constraints make it impossible to prototype and test every design idea and much can be learned from simulation results, which cannot be obtained in the test chamber. Actran, MSC Software Company’s acoustic simulation solution, based on Finite Element Analysis (FEA) technology, provides predictive simulation capabilities to assess the vibro-acoustic performance of audio devices, which include speakers and microphones.

audioXpress December 2015 included another great Practical Test & Measurement article on “Testing Audio ADCs and DACs,” written by David Mathew from Audio Precision. As he explains, the articles discuses methods used to procure high-quality results by correctly evaluating the critical AD and DA stages, with conventional and more evolved measurements used in audio tests. The article also includes an interesting side-text detailing how Audio Precision found an ideal test case for the APx555 analyzer. Full article now available online.

Dan Foley discusses how audible distortion can be difficult to measure and explores the instrumentation noise floor’s impact on what can be measured. As he explains, this is an overlooked contributor for the reason we are not able to measure a particular audible “distortion,” especially with low sound pressure level (SPL) signals. This article was originally published in audioXpress, March 2016 - Focus on Test & Measurement Special issue.

Here’s the final section in our series on parts reliability, how to choose them and how to estimate their life expectancy. In the third part of this article, the author continues to examine electronic components, and discusses what we can do about reliability. This article series was published in audioXpress, from November 2001 to January 2002.

Everything you need to know about how parts function, and how to select and maintain them. In the second part of this article, the author continues to examine electronic circuits with a look at some common circuit components, like resistors, semiconductors, diodes, small signal transistors, power Semiconductors, and microelectronics. This article series was published in audioXpress, from November 2001 to January 2002.