Sound and sound systems - an informal perambulation

This project is not intended as an encyclopaedic or complete rendition of the subject, but a condensation of more than 30 years in the field for the benefit of students, constructors, hobbyists, amateurs and professionals who, just as I have in the past, failed to source the specific information that they seek. Originally intended as an introduction to hardware for a student already adequately equipped with maths and to fit on one 3½" floppy using the most rudimentary and common-place software, interest continues to expand it. As always, comments and additions are welcomed.

Sound, speakers (some of their design considerations), some thoughts on working with them and some tips that may prove useful.

Further thoughts, on more than 70 individual power amplifier designs covering in excess of 60 years, include;

'valves vs transistors' Dinsdale MkII ICs and modules
PE Gemini & Orion Leak Stereo / Delta PW Texan & PE Rondo
compact RCA 120W Radford HD250 / ZD22
Yamaha B-1 Sony TA-8650 Cambridge Audio 'P' series
Lecson AP3 MkII symmetrical Loudmouth (12V class C)
Beomaster 4400 Elektor 200W 'raw' RSD 800b / Phase Linear 400
Maplin (discrete) Hitachi FETs Technics SU-V6 & SE-A7
Miloslavskij class A Elektor ULP Carver M-400 (MFA)
NAD 3020 Curtis ETI System A Elektor 100W Darlington
Kuroda FET Albarry M408 / 1008     Sugden A48 MkII
TOA VP-1240 Mission Cyrus 1 PMI SSM-2131 fast FET
Giesberts HEXFET, IGBT     Stochino fast FET Arjol
Reider class G class D

Linsley Hood simple class A (1969, 1996), some MOSFET and preamp designs,

and other practical aspects such as

amplifier protection power supplies soft-starts
layouts and heat-sinking       distortion dimensioning a design
setting up an amplifier offsetting an amplifier       feedback
preamps sundry styli interfaces sound pickups
battery operation noise measurements electronic switching
Bessel arrays equalisation width
recording / mixing recycling mistakes
'paranormal audio'

The suggestion that a "crystal combination... can probably also amplify" which "will quickly relegate valve..." was made by W. T. Ditcham in the Wireless World of May 15, 1920. An excellent reading list covering early solid-state is given in Early Transistors Bibliography by Andrew Wylie. For another insight into the 1950's developments, there's an interview with Paul Penfield Jr. Another 'journalistic' view is given by The Versatile Midgets - TIME. The first solid-state hi-fi component was the Fisher TR-1 phono and microphone preamp. Steve Reyer's excellent page on the first commercial transistor radio, the Regency TR-1 is interesting also.

A good source for datasheets can be found here, less obsolete types, and for those daunted by math, the liberty has been taken to create a zipped Excel file that includes useful conversions and formulae, which can be found here. Any functional errors, as with those in these pages and any correspondence, are entirely mine as I am human too.

All the designs featured have been built and tested, if not by the author, then by others whose experience is attested. This has been a very interesting but, by necessity, specialist project ('audiophools' beware) that has grown beyond expectation (some 8 years later to 6 floppies with 674 files, some 608 of these being gifs, and 69 web pages - more than 500 printed ones) as the first index page shows. A zip-file of all the above is available for those who require no banner ads, glitches or faster access to the files offered.

The feedback has been excellent and I am grateful for it. If any philosophical point can be raised by the exercise it is probably that there is more than one way of achieving the same goal, the simplest and most succinct solutions usually being the most successful, as there is with other subjects and most of life. The sheer diversity of means by which it is possible to fulfill a function, each with it's own attendant miriads of details, impresses.

In keeping with the original concept, some designs suggested for inclusion have been omitted since it was felt that sufficient online resource already existed that in effect would have been duplicated, although it has been noted that when and where there was previously little, now a resurgence in interest and additional material is evident. On a personal level, it has been satisfying and encouraging to see the hundreds of links that have been made to these pages and the many e-mails (estimated 100:1 visitor / e-mail). If it has been at all possible to encourage others to 'spread the wealth' by providing a much needed source for particular information that couldn't be found elsewhere then I will have achieved what I intended to do when I first dipped my toe into the 'interweb' in the mid '90s. A newer and excellent site has been set up by some techs and is well worth a visit. Thank you all, especially to Peter Edwards who planted the original seed. Is there another area I should cover?

Copyright Notice. These articles, including but not limited to all text, images and diagrams, are the intellectual property of Paul Kemble, and is Copyright 1996. Reproduction or re-publication by any means whatsoever, whether electronic, mechanical or electro-mechanical, is strictly prohibited under International Copyright laws. The author (Paul Kemble) grants the reader the right to use this information for personal use only, and further allows that one (1) copy may be made for reference while constructing any project described. Commercial use is prohibited without express written authorisation from Paul Kemble.

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