Loudspeaker Measurement Tools from Physical Lab

Physical Lab, based in Senden, Germany, is a fascinating company in that it not only manufactures loudspeaker test solutions directly aimed at speaker development and research, but also provides several engineering services for the loudspeaker industry. This article highlights the three loudspeaker measurement accessories that Physical Lab manufactures — the Physical Lab Mini Reference Amplifier, the Physical Lab Imp Box, and the Physical Lab ISO Box. The article was originally published in Voice Coil, December 2017.

Audio Precision announced the expansion of its line of measurement microphones with the introduction of the 376M03, a calibrated microphone system combining a 1/2" microphone cartridge with a phantom-powered preamplifier - the 426M16 - in its 1/2" configuration. The new preamplifier combines the precision of calibrated, standardized measurement microphones with the convenience of ubiquitous mic accessories offering phantom power, balanced connections for improved immunity to induced noise, and easy connectivity via common XLR cables.

Acoustic reflections in rooms, in the form of reverberation, contribute significantly to the characteristic of sound. In acoustic measurements for quality testing of loudspeakers and microphones, however, these reflections can produce inaccurate results and should therefore be excluded as far as possible. The measurement results must be reproducible and not significantly influenced by the room acoustics. In this article, NTi Audio explains how to remove reverberation from the measurement results.

Do you know what the crossover filters are doing to the response of the loudspeaker system? Some of you might have measured the frequency response of the loudspeaker system to determine what’s happening through the crossover region. However, most designers only look at the loudspeaker’s on-axis response. It’s equally important, or perhaps more important, to know what’s happening off-axis. Let’s see how loudspeaker modeling can be used to help with this. This article was originally published in Voice Coil, August 2017.

Is the solid part of a loudspeaker motor just a magnet or is there more to it? Simulation tools have helped to create effective and powerful magnet constructions, which make it easy to build a prototype based on calculations and experience. The next obvious step is measuring and listening to the assembled speaker. However, more conclusions can be drawn by analyzing the individual parts further. This article was originally published in Voice Coil, May 2017.

Klippel GmbH is celebrating its 20th anniversary in 2017. To celebrate, Klippel launched its new Klippel Analyzer 3 (KA3). The Klippel Analyzer 3 is an hardware platform for R&D modules and Quality Control (QC) tasks that performs the data acquisition and real time processing. It is connected to a Host-PC / dB-Lab via USB 2.0, and accepts a series of KA3-Frame and Cards to plug in. This article was originally published in Voice Coil, September 2017.

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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.