The Issue 3, 1975 edition of The Audio Amateur is a technical powerhouse that bridges the gap between classic craftsmanship and the digital future. Here are the highlights of this issue:
- A Bilateral Clipping Indicator: Stop guessing if your amplifier is struggling with transients. Build this real-time indicator that provides a visible warning whenever your system is driven to clipping—saving your speakers from damage and your ears from fatigue.
- Audio Research: A Profile: Go behind the scenes with a legend. In this extensive interview, William Z. Johnson reveals the uncompromising design philosophy and rigorous testing that have made Audio Research a world leader in "state-of-the-art" linearity and music reproduction.
- The Compact Tower: Achieve "exceptional clarity and spaciousness" without sacrificing your living room floor. These high-performance, omni-directional towers provide an open, airy character and deep bass response that rivals far larger, more expensive conventional designs.
- Two Out of One: Master your home’s audio distribution. This clever control system allows you to manage two separate audio programs and multiple speaker sets across different rooms simultaneously, ensuring everyone in the house hears what they want.
- Audio Basics: What is PCM?: Peer into the "undisputed" future of audio. Reg Williamson explains the ground-breaking technology of Pulse Code Modulation (PCM) and how it promises to deliver absolute fidelity in broadcasting and recording.
- Showcase: Electrostatic Monitoring: Explore a high-performance solution for on-location mastering. Roger Sanders shares his custom-built 20-watt Class A amplifier designed specifically to drive electrostatic headphones with stunning, "veil-lifting" transparency.
- In Defense of the Ear: Join the debate on how we truly evaluate sound. This provocative article challenges traditional loudspeaker measurement theories, arguing that trained human hearing remains the ultimate tool for judging high-fidelity performance.
- Classic Circuitry: The Heathkit XO-1: Reference a vintage pioneer. This issue features the complete, detailed schematic for the Heathkit Electronic Crossover, a valuable resource for restorers and tube enthusiasts alike.
Table of Contents
- A Bilateral Clipping Indicator: by C.W. Russell ..................................................................... 3
- Audio Research: A Profile: Interview with William Z. Johnson ............................................. 6
- The Compact Tower: by Lynn B. Neal .................................................................................... 12
- Two Out of One: by Eric West ................................................................................................. 18
- Audio Basics: What is PCM? Part I: by Reg Williamson ...................................................... 22
- Audio Aids: by readers Williams, Sommerwerck, Gunderson, Boyd, and Thoroman ...... 26
- Book Talk: by R.H. Miller and Brent Gabrielsen .................................................................... 30
- Showcase: Roger R. Sanders' electrostatic headphone system ........................................ 34
- In Defense of the Ear: by James S. Upton ............................................................................ 36
- Classic Circuitry: The Heathkit Electronic Crossover Model XO-1 ...................................... 40
- LETTERS .................................................................................................................................... 41
- CORRECTIONS .......................................................................................................................... 42
- CLASSIFIED ................................................................................................................................ 45
- AD INDEX ................................................................................................................................... 45