Loudspeaker Modeling and Design: A Practical Introduction
346 pp., hardbound, $US170
In writing Loudspeaker Modelling and Design: A Practical Introduction, Geoff Hill intended to offer a realistic and worldly approach to loudspeaker design to an audience already initiated into the world of audio theory. The book aims to ignore the tropes of typical theory laden textbooks in favor of clear and concise language. As an acoustician by trade and a lifelong musician, the details behind varying loudspeaker designs have been in my peripheral for some time. Having a surface level understanding of loudspeaker anatomy, I found the book to be an introduction to the strategic planning, design, and implementation of loudspeaker testing. The book is primarily aimed at those with a background in physics or acoustics eager to explore the world of loudspeaker design but unsure where to look for a practical application of loudspeaker theory.
The book is divided into eight parts. Hill begins by addressing the theory behind loudspeaker functionality, maintaining a ﬂuid pace by peppering more intensive theory only when it is necessary for the reader to grasp the larger concept, but leaving the proofs for many statements for the reader to investigate. Hill then describes his practical approach to modeling the performance of a loudspeaker. These explanations take place in parts 1 and 2. In parts 3 and 4, Hill explains many of the common methods for modeling the performance of loudspeakers such as polynomial models and the small signal model. While the explanations of a wide variety of loudspeaker modeling techniques are helpful, Hill acknowledges that these methods are not one-size-ﬁts-all and describes the importance of understanding the goals of the loudspeaker being designed and how these goals will determine the most useful modeling process. Hill also maintains this practical approach by describing to the reader how different materials may impact the budget of the loudspeaker’s design and how certain design criteria may save on cost but will limit the performance of the loudspeaker in loudness, frequency, performance, or durability.
In the later parts of the book, Hill describes methods of gauging the performance of loudspeakers after they have been built. These include general methods of acoustical testing in anechoic chambers and, more speciﬁcally, testing methods for the accurate measurement of loudspeaker components such as the drive units. The ﬁnal section of the book also contains Hill’s white paper on tetrahedral test chambers. This white paper makes comparisons between loudspeaker measurements made using a traditional IEC bafﬂe and those made using tetrahedral test chamber. The measurements from the tetrahedral test chamber are found to be clearer than those using a traditional IEC bafﬂe, and Hill postulates that the simpliﬁed setup of the tetrahedral test chamber offers increased repeatability over more complicated methods. After this white paper, Hill has an appendix that includes detailed instructions for loudspeaker modeling using software such as ABEC (Acoustic Boundary Element Calculator), VACS (Visualizing Acoustics), FEMM (Finite Element Methods Magnetics, an FEA magnetics program by David Meeker), Fusion360, and more. These tutorials offer the reader many different ways to begin digitally modeling a loudspeaker design, and Hill provides the reader with lines of code to aide those unfamiliar with the software.
The book also includes a short biography of the author. Geoff Hill has been a contributing member to the Audio Engineering Society for many years and has worked with multiple consultancies in the UK throughout his career, as well as with technology companies such as Motorola and Bowers & Wilkins. He is a graduate of Greater Brighton Metropolitan College and now consults on loudspeaker design privately through his latest venture, Hill Acoustics, located in Cambridgeshire, UK.