A short review of Ray Aldenâ
€™s Speaker Building 201.
I’ve looked forward to the release of Ray’s new book for some
time now. His previous book Advanced Speaker Systems, now out of
print, was something of an alma mater to my then neophytic speaker
building skills. I fondly recall many happily spent hours solving the worldâ
€™s speaker building mysteries with his book and the aid of a scientific
calculator. Consequently, when I heard Ray was writing a new book, I
corresponded with Ed Dell of AudioXpress and asked if I could obtain an
advanced copy of Ray’s second offering for the purposes of writing a
review. Ed graciously complied, and last week a copy of Ray’s book
was delivered.
Ray was a math teacher at Stuyvesant High School for 28 years and offered a speaker building class to
the seniors as a practical application to a course normally taught in the abstract. Ray is something of an
antithesis to every math teacher I’ve ever known in that his instructional style is very clear and easy to
understand. The formulae in the book, -and yes, there are a lot of them, are clearly explained as to
purpose and function. His book includes Math Tips sections at strategic points for those of us who’s
skills may have entropied or for whatever reason need a little brushing up in basic algebra. For those
wishing to learn the basic to intermediate levels of speaker building but are intimidated by all those
incomprehensible equations, this is the book for you! Ray has written this book for everyone, not only
covering the speaker design arena, but he also addresses woodworking and cabinetry methods, examples
of utilization of some of the on line calculators, and enough information to build eleven different speaker

Chapter 1, aptly titled “The Adventure Begins� starts out with an overview on how the book may
be utilized. One does not need to read every chapter to gain benefit from this book. Some will likely just
skip to Chapter 11 and avail themselves to one of the eleven speaker designs documented there. Others,
who may be woodworking challenged, will enjoy his construction suggestions in Chapter 12. Chapter 1
includes a short history of sound reproduction, and also covers the basics of speaker design, including
driver construction, explaining the Theil/Small parameters, the physics of sound, driver selection and
enclosure selection. Chapters 2 and 3 discuss the parameters of Vas, fs, and Qts in relation to closed and
vented box design. Driver and box compliance is discussed as well as the total Q of the speaker. There
are numerous formulae and math tips in these chapters, as well as many informative figures. The vented
chapter covers Helmholtz resonators in a very intuitive fashion and a section is included on the differences
between closed and vented boxes.

Chapter 4, “Opening Pandora’s Box� gives everyone a break from the formulae introduced in
the first three chapters. Instead it focuses on downloadable and on-line calculators, and walks you
through how they may be used. He also provides some handy formulae for calculating the volumes of the
frustrums of cones, pyramids, and trapezoids, which are quite useful in calculating the volume displaced
by drivers and in enclosure design. In Chapter 5, “Special Applications, Ray discusses multiple driver
formats, dual voice coil drivers, and the resultant changes to the T/S parameters. A brief discussing of
vertical lobing is included, explaining the differences of  various filter orders on both MT and MTM
designs. For you analytical types, there is an abundance of formulae in this chapter as well. Chapter 6
covers various subwoofer designs including sealed, vented, bandpass, and isobaric. He also illustrates the
various methods to connect a DVC isobaric system, as well as the T/S changes that result.

Chapter 7 is entitled “Two-way Crossovers� For the fledgling speakerbuilder, this chapter is a
must read. A very informative introduction to inductors and capacitors is provided, explaining their
function and their respective phase characteristics. Constant Power Configuration (CPC) and All Pass
Configuration (APC) crossovers are discussed, as well as first, second and third order topologies.
Crossover component formulae abound in this section, as well as references to web resources. A
summation of Robert Bullock’s and Ralph Gonzalez’s modifications to the classic ‘textbookâ
€™ formulae is provided. This section may be of particular interest to some, as these modifications in
part address diffraction losses and response peaking, and more closely emulate ‘real world’
conditions. In addition, impedance compensation, attenuation, and series notch filter formulae are also
provided. Chapter 8, “Three-way Crossoversâ€� opens with Dante’s very apt quote: â
€œAbandon all hope ye who enter here.â€� And Ray quickly points out that 3 way networks are not
just simple derivatives of 2 way designs. A textbook second order APC crossover is discussed, as well
as using design ratios to compensate for the reactive components in the midrange network. He also
presents Dr. Bullock’s modifications to the standard APC crossovers, which also compensate for the
bandpass gain of the midrange section. The relative strengths of transformation and cascade bandpass
topologies are discussed. The formulae for a third order APC is also provided. In both Chapters 7 and 8,
numerous examples of the utilization of the formulae are provided as an aid in understanding..

Chapter 9 “Hardware and Software� describes the hardware product Woofer Tester and
examines software offering BassBox and X-over Pro by Harris Technologies, demonstrating how them
may be utilized with many figures and examples. Data importation is covered as well as the effects of
variations in enclosure size on maximum power, cone travel, and vent velocity. The importance of
impedance phase is discussed. An example of a three-way design using X-over Pro is shown. Chapter
10 “Crossover Optimization and Measurement techniques� takes us back into the world of
abstract thought, with a short history lesson on mathematics, discussions on real and imaginary numbers,
Nyquist plots and Heyser spirals. He provides an interesting scenario of 3 crossover designs done by
individuals of differing skill levels and compares their results using the actual driver responses. Using the
same drivers, he also details the derivation of an optimized crossover using a professional crossover
program. He finishes up the chapter with an excellent introduction on Fourier analysis, and the Fast
Fourier Transform.

Chapter 11’s title is self-explanatory. “Eleven Speaker Systems� provides documentation for
building a sub, three 2-way designs (one of which is a horn), two MTM’s, a 2.5-way or TMM
design, three 3-ways, and a complete home theater system. Drivers are all well known and among
others¸ representatives from Vifa, Focal, Eton, Raven, Morel, Peerless and Usher are in attendance.
The costs of the designs range the full gambit from pedestrian to aristocratic. Dr. D’Appolito
authored several of these designs, and sufficient data is provided for completion of all the designs sans
one, whose enclosure plans can be found on the Internet. Independent listening impressions are also
provided for each of the designs. These designs cover a wide area of interests and I have no doubt that
most everyone will find at least one design to spark their fancy. Chapter 12 “Construction� rounds
out this excellent speaker building tome with several sections concerning enclosure planning, materials,
cutting jigs, cabinet joinery, and crossover construction. He also includes construction tips for the speaker
cabinets presented in chapter 11.