About the Author
Dr. Richard Honeycutt bought a Popular Electronics magazine from the rack at a bus station in 1960. It contained an article on building a transistorized audio amplifier, which captured his interest. He followed up by subscribing to several electronics magazines. To avoid the cost of parts, he built up a "junk box" by disassembling trade-in TVs from his uncle's furniture store. His dad bought him the Van Valkenburg, Neville, and Nooger Basic Electronics book set, so he learned about tube circuits as well as transistors. He started repairing electronic devices about 1965, earning his First-Class Commercial FCC license in 1969. He has worked part-time in broadcast radio engineering and audio electronics repair since 1968, in addition to full-time work in acoustical and audio system design, plus a 20-year stint teaching electronics at the college level.
Hollow-state power amplifiers have gone through a series of stages since they first escaped the confines of home radio receivers. The first state stage focused on the early triode-based single-ended (SE) power amplifiers for cinema use (Photo 1). Then came triode-based push-pull (PP) power amplifiers using input transformer and transformer phase splitters. (The Western Electric Model 92 is such an amplifier, and visually resembles the Model 91A.) Next, we have push-pull power amplifiers using RC-coupled inputs and transformerless phase splitters. These mainly used pentodes or beam power tetrodes. And then, Williamson-type power amps with overall feedback including the output transformer in the feedback loop followed by ultra-linear amplifiers. Now let's recap those findings from my previous two articles and compare them to the last two families of amplifiers.
Early Triode Single-Ended Amps
This story is from the October 2022 edition of audioXpress.
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This story is from the October 2022 edition of audioXpress.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 9,000+ magazines and newspapers.
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