Electronics for Vinyl

622 Pages·2017·16.97 MB·English

by  Douglas Self

Electronics for Vinyl
Electronics for Vinyl is the most comprehensive book ever produced on the electronic circuitry
needed to extract the best possible signal from grooves in vinyl. What is called the “vinyl revival”
is in full swing, and a clear and comprehensive account of the electronics you need is very timely.
Vinyl reproduction presents some unique technical challenges; the signal levels from moving-
magnet cartridges are low, and those from moving-coil cartridges lower still, so a good deal of
high-quality low-noise amplification is required.
Some of the features of Electronics for Vinyl include:
integrating phono amplifiers into a complete preamplifier;
differing phono amplifier technologies; covering active, passive, and semi-passive RIAA
equalisation and transconductance RIAA stages;
the tricky business of getting really accurate RIAA equalisation without spending a
fortune on expensive components, such as switched-gain MM/MC RIAA amplifiers that
retain great accuracy at all gains, the effects of finite open-loop gain, cartridge-
preamplifier interaction, and so on;
noise and distortion in phono amplifiers, covering BJTs, FETs, and opamps as input
devices, hybrid phono amplifiers, noise in balanced MM inputs, noise weighting, and
cartridge load synthesis for ultimately low noise;
archival and nonstandard equalisation for 78s etc.;
building phono amplifiers with discrete transistors;
subsonic filtering, covering all-pole filters, elliptical filters, and suppression of subsonics
by low-frequency crossfeed, including the unique Devinyliser concept;
ultrasonic and scratch filtering, including a variety of variable-slope scratch filters;
line output technology, including on zero-impedance outputs, on level indication for
optimal setup, and on specialised power supplies; and
description of six practical projects which range from the simple to the highly
sophisticated, but all give exceptional performance.
Electronics for Vinyl brings the welcome news that there is simply no need to spend huge sums of
money to get performance that is within a hair’s breadth of the best theoretically obtainable. But
you do need some specialised knowledge, and here it is.
Douglas Self studied engineering at Cambridge University, then psychoacoustics at Sussex
University. He has spent many years working at the top level of design in both the professional
audio and hi-fi industries, and has taken out a number of patents in the field of audio technology.
He currently acts as a consultant engineer in the field of audio design.
Electronics for Vinyl
Douglas Self
First published 2018
by Routledge
711 Third Avenue, New York, NY 10017
and by Routledge
2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN
Routledge is an imprint of the Taylor & Francis Group, an informa business
© 2018 Taylor & Francis
The right of Douglas Self to be identified as the author of this work has been asserted by him in
accordance with sections 77 and 78 of the Copyright, Designs and Patents Act 1988.
All rights reserved. No part of this book may be reprinted or reproduced or utilised in any form or
by any electronic, mechanical, or other means, now known or hereafter invented, including
photocopying and recording, or in any information storage or retrieval system, without
permission in writing from the publishers.
Trademark notice: Product or corporate names may be trademarks or registered trademarks, and
are used only for identification and explanation without intent to infringe.
Library of Congress Cataloging-in-Publication Data
Names: Self, Douglas, author.
Title: Electronics for vinyl / Douglas Self.
Description: New York ; London : Routledge, 2017.
Identifiers: LCCN 2017006870 | ISBN 9781138705449 (hardback) | ISBN 9781138705456 (pbk.)
Subjects: LCSH: Audio amplifiers. | Phonograph—High-fidelity systems.
Classification: LCC TK7871.58.A9 S45224 2017 | DDC 621.389/33—dc23
LC record available at https://lccn.loc.gov/2017006870
ISBN: 978-1-138-70544-9 (hbk)
ISBN: 978-1-138-70545-6 (pbk)
ISBN: 978-1-315-20217-4 (ebk)
Typeset in Times New Roman
by Apex CoVantage, LLC
To Julie, with all my love
Contents
Acknowledgements
Other Titles
Preface
Chapter 1 The Basics
Chapter 2 Passive Components
Chapter 3 Opamps and Their Properties
Chapter 4 Preamp Architecture
Chapter 5 Moving-Magnet Inputs: Phono Amp Architecture
Chapter 6 Signals From Vinyl: Levels and Limitations
Chapter 7 RIAA Equalisation
Chapter 8 Archival and Non-Standard Equalisation
Chapter 9 Moving-Magnet Inputs: Noise and Distortion
Chapter 10 Moving-Magnet Inputs: Discrete Circuitry
Chapter 11 Moving-Coil Head Amplifiers
Chapter 12 Subsonic Filtering
Chapter 13 Ultrasonic and Scratch Filtering
Chapter 14 Line Outputs
Chapter 15 Level Indication
Chapter 16 Power Supplies
Chapter 17 Moving-Magnet Inputs: Practical Designs
Appendix 1: Component Series E3–E96
Appendix 2: Phono Amplifier Articles in Linear Audio
Index
Acknowledgements
My heartfelt thanks to:
Gareth Connor of The Signal Transfer Company for unfailing encouragement, providing the
facilities with which some of the experiments in this book were done, and with much
appreciation of our long collaboration in the field of audio.
Other Titles
Self On Audio: The Collected Audio Design Articles of Douglas Self
Small Signal Audio Design
The Design of Active Crossovers
Audio Power Amplifier Design
Preface
“The End … is the Knowledge of Causes and secret motions of things, and the enlarging of the bounds of
human empire, to the effecting of all things possible.”
Francis Bacon, New Atlantis
“Another damned thick book! Always scribble, scribble, scribble! Eh, Mr. Gibbon?”
Attributed to Prince William Henry, Duke of Gloucester, in 1781 upon receiving the second volume of The
History of the Decline and Fall of the Roman Empire from its author.
This book aims to give a comprehensive account of the electronics needed to extract the best
possible signal from grooves in vinyl. This is timely, as what is called the “vinyl revival” is still in
full swing. Vinyl reproduction presents some fascinating technical challenges; the signal levels
from moving-magnet cartridges are low, and those from moving-coil cartridges lower still, so a
good deal of low-noise amplification is required. In the moving-magnet case this is much
complicated by the high inductance of the cartridge. RIAA equalisation is required for a flat
response, and achieving this both accurately and economically is a major study in itself. Vinyl
produces large amounts of subsonic noise, and this has to be filtered out both effectively and
unobtrusively to prevent bad things happening in amplifiers and loudspeakers.
Some of the basic material was published in my Small Signal Audio Design (2nd edition). When
the time came to consider updating the book, there was the problem that its length was already
pushing the limits for practical publishing. I have heard it said you should never write a book you
cannot pick up with one hand. This issue was solved by splitting off everything related to vinyl
reproduction and adding a great deal of new material to make a new and separate book focused
on vinyl electronics. Here it is, containing more than three times as much text and more than
three times as many illustrations; most of the content is new material. There are new chapters on
phono amplifier architectures and ultrasonic and scratch filtering. The new chapter on subsonic
filtering is, I think I can say without fear of successful contradiction, the most comprehensive
account of it ever published. I have tried to make it easy to dip into this book—not everyone will
want to read it straight through. A few important concepts are therefore explained more than
once, when they are particularly relevant. I hope you will not accuse me of hesitation, repetition,
or deviation.
The focus is on the analogue domain, where the processing is done with opamps or discrete
transistors, usually working at a nominal level of a volt or less. There are good reasons for this.
While you can do almost anything in the digital domain, you first have to get the signal into the
digital domain. Since the nominal signal level from a moving magnet is only 5 mV rms and the
output from a moving-coil cartridge generally much lower than that, clearly you are going to
have to quite a lot of analogue amplification before you can apply it to the input of an A-to-D