CONTENTS
1. One digit at a time. Digital electronics. Digital signals. Paying the price.
2. Digital devices. Gates. Sequential circuits. Registers. CMOS ICs. Memory ICs. Microprocessors. Obtaining clock pulses.
3. Analog to digital conversions. Conversion and modulation. Conversion. Sampling rate. The sampling process. Conversion. Negative numbers. Error checking.
4. Digital to analog. Simple systems. Current addition. Conversion problems. Before conversion. Oversampling. Bitstream methods.
5. Studio digital methods. Digital tape. The tape bandwidth problem. Rotary head techniques. Consoles and editing. Tailpiece. The MASH system.
6. The CD system. Introduction . The optical system. EFM modulation system. Error correction. Control bytes. Summary. Bitstream tail piece .
7. Consumer digital tape systems. The systems. The DASH system. The S-DAT system. The R-DAT system. The DCC system. The digital Mini Disc. The Denon DTR-2000.
8. Sound synthesis. New sounds. Synthesis methods . MIDI action.
Appendix 1: Further reading
Appendix 2: Glossary of terms
Appendix 3: Polarization of light Index
PREFACE:
The impact of digital methods on domestic sound reproduction has been as delayed in reaching us as it has been inevitable . Digital recording methods have existed for many years and have been familiar to the professional recording engineer, but the compact disc (CD) was the first device to succeed in bringing digital audio methods into the home, though Laservision (using analog methods along with the optical disc recording system) had previously tried to break into the video market with limited success. Compact discs are now well established, to the extent that newspaper reviews of new issues concentrate more on CD releases than on releases on other media such as tape or LP (now referred to as 'black-disc' ). In addition, several manufacturers are releasing new issues on CD only.
All this development has involved methods and circuits that are totally alien to the technician or keen amateur who has previously worked with audio circuits . The principles and practices of digital audio owe little or nothing to the traditional linear circuits of the past, and are much more comprehensible to the computer engineer than to the older generation of audio engineers . This situation has not been helped by the appearance of books that make the assumption that the reader has already mastered digital circuitry and also the mathematics of signal encoding. Since even the basics of digital circuitry are so totally unlike anything in linear circuits, the first two sections of this guide are devoted to digital principles and circuit devices rather than directly to digital audio . This guide is intended to bridge the gap of understanding for the technician and the keen amateur rather than for the professional audio engineer . In other words, the principles and methods will be explained, but the mathematical background and theory will be avoided other than to state the end-product. My aim is to show what is involved in the digital part of audio signals, particularly in the newer devices such as CD and DAT, rather than to go into details of sampling, error-correction and other esoteric points. It is important to note that digital audio methods at present account mainly for the CD player or the DAT player in the home, and at the time of writing the remainder of the audio chain of preamp and main amplifier remain firmly analog with a few exceptions.
I am most grateful to all who have helped in this effort, particularly to Philips and Sony who have supplied vital information. I owe a special debt of gratitude to Warren Taylor who first suggested this guide and has published it online.
-KH
Preface to the second edition
Since the first edition was published, many important developments have taken place in digital audio, and much more information is available . In particular, this guide now deals with techniques such as oversampling and bitstream methods which were neglected earlier, and also looks at the Digital Compact Cassette, the Sony Mini Disc and the new domestic DAT players which are just appearing on the market.
* For enthusiasts, technicians and students *
* Digital techniques explained non-mathematically *
* Covers CD and DAT *
* New sections on oversampling and bitstream methods *
* Glossary of terms
* Digital audio involves methods and circuits that are totally alien to the technician or keen amateur who has previously worked with audio circuits. This guide is intended to bridge the gap of understanding for the technician and enthusiast . The principles and methods are explained, but the mathematical background and theory are avoided other than to state the end product . This second edition has been updated to include sections on oversampling methods and bitstream techniques . The opportunity has also been taken to add a glossary of technical terms.
Reviews of first edition
'Readable and informative' Home & Studio Recording
'Well worth a read ... the writing is clear and unambiguous'
Also see: