2006 Winter Symposium: Training Sessions, Tutorials and Invited Technical Papers

Training Sessions
Earl Geddes presented an all-day technical training program on ‘Spectral Analysis – the foundation of acoustical measurements’, and Dan Digre from Misco presented a half day course entitled ‘Loudspeaker 101 for non-technical professionals’.
Course notes are only available to people who registered for the course. Contact ALMA if you attended ether of these seminars and would like a copy. We’re interested in hearing what subjects you would like to see covered in nextyears training programs, so drop us a line and let us know.

Invited Technical Papers

(all paper titles will link to a PDF file of the paper)

CEA2010: Standard method of measurement of powered subwoofers; Brad Starobin - Polk Audio
CEA2010 establishes a standard for measuring and reporting on the audio performance of consumer oriented powered subwoofer systems.  A protocol for determining distortion and noise-limited acoustic output capability involving the use of toneburst stimuli over a powered subwoofer’s 20-80Hz two-octave passband, CEA2010 reflects the Consumer Electronic Association’s attempt to arm consumers with meaningful performance-oriented metrics for making intelligent purchasing decisions.   This paper will cover CEA2010’s measurement and reporting protocol, the rationale for its amplitude and frequency dependent multi-tiered distortion limits and will present the measurement results for subwoofers of various designs. - UPDATED - April 10, 2006. You can purchase a copy of CEA-2010 by going to IHS Global Engineering Documents at http://global.ihs.com.

Loudspeaker System Providing Improved Off Axis Frequency and Power Response to Achieve Superior Soundfield ; Ira Pazandeh - Episode Audio
Attempts to achieve a more natural sound field through complicated electronics means have generally failed. The present invention is a new loudspeaker design that produces better music intelligibility by minimizing beaming and creating a wide dispersion of sound. Conceptually, it creates a desirable sound field by extending the MTM configuration for improved off axis and power response. The invention achieves the described objectives by teaching certain benefits in construction and use.

Rub & Buzz Testing Beyond the Human Ear; Wolfgang Klippel & Stefan Irrgang - Klippel GmbH
Objectives of the presentation:
- Do we need the detection of inaudible Rub & Buzz defects in end-of-line-testing?
- Physics of rub & buzz effects: Time domain analysis required
- Where to set the cut-off frequency of commonly used tracking high-pass filters?
- New technology IDD (Isolated Defect Distortion) for separating defects from inherent wanted properties
- Reliable detection of spurious defects (loose particles) before they become worse after shipping

A New Method for Measuring Multitone Distortion using Non-Coherence; Steve Temme - Listen, Inc.
Multitone is a popular test signal for fast frequency response measurements. It also should be a more rigorous test signal for assessing system non-linearities because it excites many frequencies simultaneously and can measure both harmonic and intermodulation distortion products. Some would say it is closer to music than a sine wave, two tones, or noise.

System theory shows that more than two tones are needed to fully characterize a non-linear system. Multitone measurements, however, are challenging because the number of intermodulation tones grows exponentially in relation with the number of stimulus tones. A new approach based on measurement of non-coherence between stimulus and response is presented. This method is easy to implement, provides a continuous distortion curve against frequency, and can be used with a noise stimulus, the extreme type of multitone.

A Real-Time System for Voice Coil Temperature Measurement; Marshall Buck - Psychotechnology, Inc.
A four channel data acquisition system has been designed and tested for measurement of four parameters needed for thermal testing and modeling in a voice coil driven loudspeaker: Voice coil temperature, RMS voltage drive, current, and true V x I power dissipated. These data are stored in Excel format for post-processing. Handling 32 amperes, and 125 volts, It is suitable for voice coils rated up to 4000 Watts.

Precise Material Parameters required for FEA?; Wolfgang Klippel - Klippel GmbH / Matthias Ringpfeil - Dr. Kurt Mueller & Co. KG

Rubber, fabric, paper and other special loudspeaker materials with and without treatment are not given in literature and material libraries of common FEA software. A reliable method is developed for measuring the material parameters (Young’s E-modul, damping) dynamically. The agreement between predicted and measured transfer responses is investigated by using a variety of materials systematically modified by different treatments. Practical consequences for cone and suspension design are discussed.

Tutorial Sessions

(all tutorial titles will link to a PDF file of the presentation)

An interesting selection of tutorial sessions and technical papers on a variety of manufacturing topics was presented. Clickon the paper title for a downloadable PDF version of the presentation.

A Primer on Intellectual Property – Andy McKinney, Jones, Tullar &Cooper PC. This tutorial explored what every business person should know about intellectual property e.g. patent, trademark, copyright, trade secrets etc.

New Adhesive Technologies -  Mike Shannahan, Henkel-Loctite. An overview of new and upcoming adhesive developments and their benefits to speaker manufacturers

The Fine Software suite from Loudsoft – Peter Larsen, Loudsoft. The new features of three loudspeaker design software packages and a new QA system were presented.

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