Understanding Hi-Fi Circuits

Norman Crowhurst was the nearest thing to a perfect audio author audiophiles have ever had and was also marvelously understandable by all levels of readers. Fortunately, he wrote on a wide variety of audio topics. His untimely death in 1992 was a major loss to audiophiles everywhere.

This volume (first published in 1957) is vintage Crowhurst, amazingly insightful but also down-to-earth. The underlying theme of the book is the fact that absolute perfection in audio circuitry is impossible. Therefore in each chapter, Crowhurst discusses all the relevant design choices involved in a selected class of audio components and how to reach a balance of design compromises.

The book's title, Understanding Hi-Fi Circuits, clearly states his theme which he discusses in his introductory section. From there he goes on to what he considers the single most important audio ingredient, the power amplifier's output stage. In chapter three he looks at feedback which continues to be a highly controversial, complex question. He moves back through amplification to the inverter and driver stages in chapter four, covering the choices with his usual practical thoroughness. Input stages come next in chapter five, where noise, hum, and all the tough related low-level questions are considered.

Matching is the theme in chapter six, an arcane and difficult concept which Crowhurst explains with ease and confidence. He takes on equalization issues next, explaining the choices for phono and tape hardware and the required standards for accurate reproduction.

Chapter eight tackles the thorny issue of loudspeakers and their crossovers, along with channel separation methods. What to do about human hearing's quirky characteristics related to loudness is his next topic. Chapter nine is a comprehensive discussion of the variety of attenuator types.

His penultimate chapter ten explores tone controls all the way from single step types to variable slope versions. His final chapter sums up the field and the many topics his book is unable to cover. This book will help you to get a full grasp of audio issues that matter and make informed decisions

• Tone controls
• Loudness
• Equalisation
• Load matching
• Diagrams throughout