Last Updated: 20050331, meiSaturday, May 28, 10:30 — 12:00
Chair: David Josephson, Josephson Engineering - San Jose, CA, USA
B-1 A Flexible Compander IC for Wireless Microphone Applications—Gary Hebert, THAT Corporation - Milford, MA, USA
A new IC for implementing companding noise reduction in professional wireless microphone applications is described. Unlike existing devices designed primarily for the cordless telephone market, the new design allows straightforward, repeatable implementation of companding schemes incorporating ratios greater or less than 2-to-1, level-dependent ratios, limiters, and noise gates. The overall device architecture and design and performance of individual functional blocks is described. Several examples of encoder and decoder implementations are presented. The design techniques used to maintain wide dynamic range while minimizing power consumption are described.
Convention Paper 6337 (Purchase now)
B-2 A Better Approach to Passive Microphone Splitting—Jim Brown, Audio Systems Group, Inc. - Chicago, IL, USA; Bill Whitlock, Jensen Transformers, Inc. - Van Nuys, CA, USA
While there are clear technical advantages to active microphone splitting, operational considerations dictate the use of passive splitting of microphones in most sound reinforcement applications. Modern microphones generally require a load impedance greater than 1,000 ohms, and performance often degrades significantly with heavier loading. Since mix desk input impedances rarely exceed 1,500 ohms, passive splitting utilizing 1:1 turns ratio transformers can seriously degrade microphone performance when driving two or more mix desks. Transformers designed to operate in stepdown mode solve this problem and offer other benefits. This paper reviews current practice, studies stepdown-mode splitting, and recommends that mixing desks be designed with higher input impedances and that microphones be designed to work with lower impedance loads.
Convention Paper 6338 (Purchase now)
B-3 Electro-Magnetic Interference, Microphones, and Cables—Martin Schneider, Georg Neumann GmbH - Berlin, Germany
All electronic devices in the audio chain are susceptible to external electromagnetic interference. Interfering signals are moving higher and higher in the radio frequency spectrum, the current most important disturbing element being cellular phones. Standardized measurement systems are available. Although mentioned in the relevant microphone standards, data is seldom published. Actual measurements on different microphones, cables, and wiring topologies shall be presented and discussed.
Convention Paper 6339 (Purchase now)
©2005 Audio Engineering Society, Inc.