Microphones in Action
by Vivian Capel
Published by Fountain Press
Price £5.00 in softback
It is always hard to write a book about a continuously changing field, in this case microphones. The writer may play safe and keep to the theory ignoring all the 'real' items, thus leaving the reader no wiser about what to use for an application, or include up to the minute technology that quickly becomes dated. Vivian Capel succeeds admirably in the first part of his book, illustrating the theory with plenty of photographs of actual microphones showing commercial application of the theory. Indeed, the whole theory section (which occupies the first 7 chapters) is excellent. It is clearly laid out and for the most part the text is easy to read, although the small size of some of the data tables will require a careful eye.
With the theory out of the way, methods of connecting up microphones are considered. Again the explanation is lucid and accompanied by diagrams that illustrate the text well. I would have preferred to have seen more circuit diagrams at this stage since most of the explanation stops at the block diagram stage leaving the reader to search elsewhere for suitable circuits.
The second part of the book deals with actually using a microphone to make a recording, and opens with a description of reverberation and room styles leading to some of the problems which occur. A chapter entitled 'Choosing The Right Microphone' may well lead the reader to believe that suggestions of the best microphone for certain jobs will be made, and to a limited extent this is true. The type of microphone required is suggested, leaving the reader to thumb through the first half of the book for an example. It is also a pity that 'pop groups' are dismissed in 8 lines. Moving on to actually using the microphones and interesting points start to emerge, but not much mention is made to tricks of the trade, such as rolling off the bass when recording acoustic guitars to obtain a 'clean' sound. Most sort of applications are covered with several pictures to demonstrate the technique involved. 'Pop groups' are again glossed over and a few words, for example, about the miking up of a drum kit would not be out of place since the methods are very interesting.
All in all however, this is a good book for the beginner, and the experienced user who wishes to become more acquainted with the theory. Provided that the main interest is not with 'pop groups' (which are hardly mentioned) the book is worth reading.
Newnes Book of Audio
Edited by K. G. Jackson
Published by Newnes Technical Books
When a book comprises a compendium of manuscripts written by different authors, there is a real danger that the outcome will be simply a collection of disjointed articles that just happen to reside between two covers.
In no way does the Newnes Book of Audio fall within this category, being well presented and with good continuity throughout. Each author compliments his literary 'bed-mates', referring freely to other sections but avoiding duplication.
The seven authors, each established experts in their own fields, have managed to paint a comprehensive picture of the audio scene both from an equipment and application viewpoint. Although written in easy-to-understand language, suitable for beginners, the book still holds some areas of interest for the enthusiast.
Divided into ten sections, with six additional items of background interest, the whole field of audio, with particular reference to hi-fi, is explored both in general and technical terms. Line diagrams and photographs are liberally used and complement the text.
Each section of the book covers a distinct area of the world of audio taking one through recorders, disc reproduction, tuners, aerials, amplifiers, microphones and loudspeakers. Of special interest are sections on the making of recordings (a neglected art), mobile audio systems and a synopsis of hi-fi generally.
I found the book to be well written and illustrated, easy to read and interesting although it is probably of more use to the newcomer and raw amateur than to the established enthusiast. Certainly valuable to a buyer considering a new set-up and who is confused by the abundance of equipment now available.
International Transistor Equivalents Guide
by Adrian Michaels
Published by B. Babani Ltd.
Ever since the transistor became generally available at an economic price the problem of finding substitutes has been with us. Today, with equipment being supplied from world wide sources, the vast array of semi-conductors presented to one is, to say the least, daunting. The chances of a particular transistor being readily at hand is not good and the search for substitutes difficult.
The International Transistor Equivalents Guide goes a long way to solving this problem with equivalent and near-equivalent devices being listed for over one hundred manufacturers. Using alpha-numeric sequence, the identification of a particular device is quick and easy. Included are a selection of substitutes for most of the popular, user-orientated modern transistors likely to be encountered.
The tables list concisely type number, material type, polarity, manufacturer and an indication of the application the device is most suited to. Equivalents are sub-divided into European, American and Japanese types.
It must be realised that direct equivalents are not always possible and that electrical and mechanical characteristics might differ somewhat between manufacturers. Indeed, there is occasionally slight variation between devices having the same type number. With this in mind and where circuits having critical parameters are involved, it would be wise to consult manufacturers' specifications before making a substitute.
I do feel that this book will be a valuable addition to the bookshelf of all those taking an active interest in electronics and will augment the various transistor data books that are available.
Electronic Synthesiser Projects
by M. K. Berry
Published by B. Babani Ltd.
This book contains about ten separate building-brick type projects, discounting power supplies. The accompanying circuit descriptions are reasonably informative but certainly not over-detailed. I would prefer to see just a bit more detail, particularly as there are one or two configurations which might cause problems if taken at face value, the key trigger switches on the 'Keyboard and Sample and Hold' being a particular example.
On the plus side these projects are all cheap to build and readily available components have been used wherever possible without sacrificing circuit simplicity.
Subjects covered include a single chip synthesiser based on the Texas SN76477N I.C. Various analogue delay line applications utilising the TDA1022 bucket brigade I.C. plus assorted, active, low-pass filters. The effects available from the delay circuits include phasing, flanging-vibrato, reverberation and echo.
One chapter of the book is devoted to sequences including construction details of an analogue sequencer and a description of its application. Although digital sequencers are mentioned in some detail there is no accompanying project which I feel is a unfortunate omission.
Two voltage controlled oscillator circuits are covered in reasonable detail and a keyboard interface is also included.
The final project in the book is an ADSR type envelope generator for amplitude control. With these building bricks connected together, the constructor should end up with a fairly good synthesiser. I am very surprised that there is no voltage control filter circuit in the book. Although it is obviously impossible to cover all aspects of the subject, this really is a curious omission.
With so few books on this subject it is impossible to make comparative judgement. However, overall this is a well balanced book with sufficient detail for the majority of home constructors.
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