Nov 2002
Meeting Review
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Nov 2002 Meeting Review |
CROWN TECHNOLOGIES: The Past, Present and Future of our Amplifiers
In November, the membership of the Toronto Section were treated to an update from Scott Potosky, Design Engineer with Crown on recent developments as well as the historical prospective. We were also treated to an update on digital amplifiers from Dr. John Vanderkooy of the Audio Research Group of the University of Waterloo.
As part of his presentation, Scott Potosky covered three product areas covered by Crown: Amplifiers, Signal Processing and Networking and Microphones. Scott took us through the history of amplifiers and Crown's participation in the market beginning in 1873 with Frederick Guthrie's Thermionic Emission Theory to Harold Black's pivotal paper on Negative Feedback Amplifiers in 1927. Based on Back's theory Crown built the first servo in 1931, Solid State Class D in 1954, Class H and G totem-pole in 1964 and 65. In 1968 we saw the introduction of Crown AB + B with VI protection (AB + B for performance and VI limiter for reliability). In 1971 Crown introduced the Grounded Bridge Amplifier "why not float the power supply" for savings and increased power - first implemented in Crowns M600 mono block. In 1975 Crown introduced Junction Temperature Simulation (JTS) first used in Crown's PSA-s Self Analyzing and their CTS Series amplifiers. In 1986 Crown introduced their Class H bi-level amplifier for bridged amplifiers under the trade name "VZ". Crown's MA5000 was the first to implement GB, JTS and VZ in one. In 1993 Crown introduced Poly-phase PWM tracking supply for grounded bridge with their BCA Class I .
Scott then went on to describe their IQ System for signal processing and networking. In the early '80's Crown successfully integrated several measurement devices and PC technology. into a single portable computer based electroaccoustic audio system - the TEF Analyzer. In 1986 Crown developed some of the first network controlled audio systems - the IQ Controlled amplifier. The product line is a platform of products made up of System Controllers, Network Media Interfaces and Audio Components.
Scott finished up the lecture with a discussion of Microphones Technologies, Signal Processing and Networking Microphone Technologies and a peak into the future.
Next Dr. Vanderkooy of the University of Waterloo continued the discussion with an overview of Class D or Digital Amplifiers. He explained that with Class D amplifiers there are a number of schemes whereby they derive the feedback. He explained that bandwidth, shielding and RF is no longer a concern with the introduction of. He went on to describe Half Bridging. He went on to discuss the concerns with regard to filtering and Class D. For more information I suggest that you contact Dr. Vanderkooy directly at the next section meeting as this reviewer does not contain the technical knowledge to do his presentation justice.
Many thanks for their efforts and wonderful presentations to Dr. Vanderkooy and Scott Potosky.
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