Loudspeaker Recipes Four Two Way Systems

"Directory of members" published as pt. 2 of Apr. 1954- issue.

Introduction to Loudspeaker Design is written for students, technicians, engineers and hobbyists seeking an overview of the technology of loudspeakers. Starting with a brief history of audio developments the book begins by introducing the concepts of frequency, pitch and loudness and proceeds to develop the idea of a loudspeaker as a system. The book covers such topics as loudspeaker design tradeoffs, spatial loading, diffraction loss, cavity effect and enclosure construction. A complete chapter is devoted to the subject of crossover design including design equations. The second edition adds a new chapter on simulation and analysis which includes design equations for closed and vented type speakers. The appendices contain technical references, design aids, glossaries and a chart depicting 18 different loudspeaker enclosure types. The author is a physicist/audio design engineer with over 35 years experience in the research and development of audio products spanning both hardware and software. His WinSpeakerz, TrueRTA and DATS software applications are widely used throughout the audio industry as tools for simulating and measuring loudspeaker performance. Captain Murphy served as a space systems analyst for NORAD during his military career. Changes for the Second Edition: The second edition brings new material and polishes the first edition with many new or improved illustrations. Chapter 2 was expanded with the second half split into a new Chapter 3 titled "Speaker Response Functions." The discussion of Thiele-Small parameters has been expanded and now covers small-signal parameters vs. large-signal parameters as it explores the role of the test signal level in parameter measurement. The crossover design chapter has been expanded to include formulas for calculating component values for the most popular crossover types. Equations have been added for calculating impedance compensation and attenuation networks. The old Chapter 7 FAQ material was integrated into other chapters as appropriate. A new Chapter 8 titled "Loudspeaker Simulation" has been added and introduces loudspeaker equivalent circuit analysis with equations for calculating the magnitude and phase responses of closed and vented loudspeaker systems. Additional design equations are introduced and then examples are given for calculating the responses of a closed box and a vented box loudspeaker. Detailed design equation summaries are given for closed and vented boxes. Appendix C was added to provide a glossary of symbols and a glossary of terms. The box type charts were moved to Appendix D.

The prospect of writing a book on loudspeakers is a daunting one, since only a multivolume encyclopedia could truly do justice to the subject. Authors writing about this subject have generally concentrated on their own areas of expertise, often covering their own specific topics in great detail. This book is no exception; the author's background is largely in professional loudspeaker application and specification, and the emphasis in this book is on basic component design, operation, measurement, and system concepts. The book falls largely into two sections; the first (Chapters 1-9) emphasizing the building blocks of the art and the second (Chapters 10-16) emphasizing applications, measurements, and modeling. While a thorough understanding of the book requires a basic knowledge of complex algebra, much of it is understandable through referring to the graphics. Every attempt has been made to keep graphics clear and intuitive. Chapter 1 deals with the basic electro-mechano-acoustical chain between input to the loudspeaker and its useful output, with emphasis on the governing equations and equivalent circuits. Chapter 2 is a survey of cone and dome drivers, the stock-in-trade of the industry. They are discussed in terms of type, design, performance, and perfor mance limits. Chapter 3 deals with magnetics. Once a source of difficulty in loudspeaker design, magnetics today yields easily to modeling techniques. Chapter 4 discusses low-frequency (LF) system performance, primarily from the viewpoint of Thiele-Small parameters. We also discuss some of the multi chamber LF systems that became popular during the eighties.

This volume seeks to lay the groundwork for readers who want to understand the general functions of loudspeaker enclosure systems and eventually experiment with their own designs. Written for design engineers and technicians, students, and intermediate-to-advanced acoustics enthusiasts, it presents a general theory of loudspeaker enclosure systems. Featuring illustrated and numerical examples, the book examines diverse developments in enclosure design, and studies the various types of enclosures as well as varying parameter values and performance optimisation. Topics examined include: the synthesis of vented systems; infinite-baffle and closed-box systems; electro-acoustical relations; and reflex response relationships.

This book is a study of the workings of dynamic loudspeakers and dynamically forced vibration. With its wealth of practical observations and real-life examples, this work will prove invaluable to the practicing motor design or loudspeaker design engineer, as well as researchers and students in electroacoustics. The book is based on a lifetime’s accumulated knowledge by acclaimed speaker designer William H. (Bill) Watkins. It differs from the usual tone of most technical books on this subject by initially presenting, and analyzing in full, the function of each key parameter of a reference dynamic loudspeaker. Each parameter’s value is then calculated and also confirmed via lab measurements to vividly illustrate all energy-transduction facets of loudspeaker operation and the forced vibration. This presentation style makes the analysis both more engaging, intuitive, and easier to comprehend compared to most previous works in the field. The principles of this book apply to all direct reciprocating motors, not just those in a dynamic loudspeaker. Unique to the book is an entire chapter dedicated to the discussion of back-EMF voltage, discussed from several technical points of view and analyzed in depth as related to the dynamic transfer of energy between the mechanical and electrical domains. Another unique feature is a detailed discussion of Watkins’ patented dual-motor concept to achieve high dynamic speaker performance in the region of its low-frequency resonance.