The Bookshelf (Sept. 1979)

Audio IC Op-Amp Applications, Second Edition by Walter G. Jung. Howard W. Sams, 1978, 208 pp., $7.95.

In the three years since the first edition of this book, there have been significant changes in the audio IC op amps available and their possible applications. Mr. Jung provides much new material that is of importance.

The first chapter is a general introduction, including right-to-the-point lists of IC op amps acceptable for various levels of audio performance. Chapter 2 is a fascinating 60 pages on the op amp parameters that are important for audio uses. There is the expected discussion on open-loop gain, the gain-bandwidth product and compensation. The coverage on slew rate and slew-induced distortion, however, is very extensive, and will tie together many loose ends for the reader. Included are correlation curves for TIM, two-tone IM and THD, complete descriptions for a THD test series, and the results for a number of op-amp types. The author also includes valuable coverage on noise and its measurement.

A short chapter discusses basic op amp configurations translated as necessary for audio applications. The last three chapters, totaling about 100 pages, provide information on many practical circuits. The first of these chapters has information on voltage amps, increasing power output, various types of preamps, power amps, and a headphone amplifier. The next chapter covers a number of equalizer types and many filter circuits, including those for rumble, notch, bi-quad, state-variable and multiple-feedback filters. The final applications chapter discusses summing amps, impedance matching, driving lines with and with out transformers, sine-wave oscillators, function generators, and other nice things.

The two appendices have a set of datasheets for the 5534 IC and ad dresses and device lists for a number of manufacturers, to aid in writing for the sheets you need. The index has good detail, and there is very good cross referencing. The book is very readable, not only because of the excellent writing, but because of a good type face and excellent illustrations.

The author includes extensive references for each chapter, an impressive total of 166 for the volume. This second edition is highly recommended to all audio engineers and technicians, including those who already have the first edition.

Howard A. Roberson--Noise Reduction Techniques in Electronic Systems by Henry W. Ott. John Wiley, 1976, 294 pp., $22.75.

The author states that this text has been written "for the practicing engineer for the design of electronic equipment ... with the emphasis on low and mid frequencies," and a very worthwhile is. The first chapter considers the general interference problem with a look at the methods of noise coupling.

Chapter 2 on the shielding of conductors and Chapter 3 on grounding detail many facets of capacitive and inductive coupling, shielding, cable construction, safety and signal grounds, isolation, and neutralization. The next chapter presents other techniques including power supply decoupling and controlling system bandwidth.

There is a close look at the possible contributions from passive components, capacitors, inductors, ferrite beads, even conductors. The 36-page chapter on shielding by metallic sheets will provide clarification for many in this area; other authors have touched the subject, but lightly. Next, Mr. Ott covers the protection of contacts to promote longer life, but also to reduce noise being radiated or introduced directly into circuits.

The final two chapters cover sources of intrinsic noise and the noise from active devices. This portion of the book gets across the essentials of thermal noise, equivalent noise bandwidth, measurement of random noise, noise factor, optimizing the source resistance, models for noise current and voltage, etc. Five appendices are included: (A) The decibel, including information on telephone industry weighting functions; (B) a summary of noise reduction approaches; (C) Reflections of magnetic fields in thin shields; (D) 50 problems, a good collection, and (E) the answers. The index has good detail with good cross referencing.

This text made a very favorable impression on this reviewer: The copy is lucid, accompanied by excellent illustrations. At the end of each chapter there is a bibliography and a helpful chapter summary, listing both the effects that might be encountered and the applicable approaches. The volume would be a worthwhile addition to the bookshelf of audio/electronic design engineers and technicians who need to keep noise under control, from small devices up to complete systems and studios.

Howard A. Roberson--Grounding and Shielding Techniques in Instrumentation, Second Edition by Ralph Morrison. John Wiley, 1977, 146 pp., $16.50.

The first two chapters cover electrostatics, capacitance and energy storage. There is discussion of the fundamentals of charges, fields, and self and mutual capacitance, which the author notes "exist physically, but are never on a parts list." Then, there is a brief chapter on the application of electro statics to practical processes. The particulars of electrostatic shielding are introduced, and the characteristics of the earth plane are examined.

The next three chapters cover subjects of interest to the users and designers of audio equipment: amplifier shielding, signal entrances, transformer shielding, differential amplifiers, and common mode and its rejection.

Of particular interest is the material on single and balanced inputs, on floating and grounded systems, and the best choice between them. There is a short chapter on the shielding of a resistance-bridge system. A longer chapter on magnetic elements and applications includes the essential instruction, "minimize the loop areas." The final two chapters are on r.f. processes in instrumentation and the earth plane.

There is discussion of problems in these areas and the possible solutions.

The index is fairly good with adequate cross-referencing. The emphasis in the book is on grounding/shielding for instrumentation, but there is helpful information for audio equipment/system design. This second edition is more of a refinement of the first edition, with relatively little new material.

Howard A. Roberson--The Complete Handbook of Public Address Systems by F. Alton Everest. Tab Books, 1978, $7.95.

The author states that the text is directed to non-technical persons who must understand PA/SR systems, but its usefulness is broader than that. The first three chapters cover elements of basic acoustics, including room effects, propagation, and hearing.

Some confusion was generated by figures 3-3 and 3-4 being interchanged and in non-standard orientation. The next chapter on types of SR systems has good coverage of some facets too often ignored, but it seemed odd to find emphasis on special mike usage, with little on what is more likely, tells how to evaluate an existing system and provides specific in formation on conducting articulation tests in a church--one of the best features of the book.

The next four chapters are on equipment characteristics and usage, micro phones, amplifiers and signal processing, loudspeakers, and the elements of audio control. There is a great deal of information contained, perhaps too detailed for some non-technical readers. The discussions of criteria for multiple-mike usage and loudspeaker lo cation and pointing are particularly noteworthy. More information would have been desirable on control, mixers, and system interconnections.

Chapters 10 to 12 concern room acoustics and EQ, fold-back systems for platform/choir areas, and the problems in multipurpose halls. There is a lot of good information, though 70-V systems are not even mentioned, a curious omission. The next chapter gives examples of relatively advanced SR systems. More applicable would be the detailing of simpler installations, complete with interconnection diagrams. The brief final two chapters contain essential points on dealing with a sound contractor and suggestions for new construction.

The appendix contains instructions for articulation tests. The glossary has well-chosen entries with good definitions. The index is quite abbreviated, especially when compared to the amount of material in the preceding 260 pages. By the author's own definition, this text is really more of a hand book for sound reinforcement than for public address. It's filled with helpful and pertinent up-to-date discussion of most areas, although systems considerations are not covered to the same level.

Howard A. Roberson--The Face of Rock & Roll by Bruce Pollock & John Wagman. Holt, Rinehart & Winston, 1978, paperback, $12.95.

This newest collection of album cover art takes the form of a retrospective of rock & roll trends with a text that takes the vantage point of a fan who grew up in the '60s.

There are serious problems with this volume all down the line. Wagman's design is static. Most right-hand pages have full-page reproductions while the left have one of four different layouts which range from the rare full-page illustration to six illustrations of one-ninth page each and a column of text.

Most curiously, nowhere in the book does a single gatefold cover appear folded out even when the design obviously cries out for such treatment, as with the cover of the first King Crimson album. Additionally, without explanation, Wagman sees fit to duplicate himself by repeating some covers several times, sometimes to good effect (facing full-page covers of Debbie Reynolds and Olivia Newton-John looking for all the world like time-warped clones), but more often purely gratuitously (including Kiss' Love Gun cover as a full page twice and only 35 pages apart).

On a technical level, the reproduction quality is erratic at best. The full pagers are, for the most part, embarrassingly grainy. The color reproduction is wildly uneven. The repeated Kiss covers' color varies almost to the point of being unrecognizable.

Pollock's text is breathlessly auto biographical and sketchy. To be sure, he makes his occasional points, but slogging through the cuteness to find them is a large bother. Better to leave the fan's fantasies aside and observe the art.

On top of it all is a steep $12.95 list price, $2.00 more than The Album Cover Album edited by Roger Dean and Hipgnosis. That one, released over a year ago, was one of the first books of album cover art and, after about a half-dozen challengers, is still the definitive one. Get it instead.

-Michael Tearson

(adapted from Audio magazine, Sept. 1979)

Also see:

Bookshelf, The (Sept. 1987)

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