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Richard's Stuff


AUDIO HANDBOOK No.1 AMPLIFIERS (Adobe Acrobat Reader required to view.)

Authored by the well known Norman H. Crowhurst.  This book is excellent for "newbies" as well as for those who have been away from tube audio to brush up on the fundamentals.  It taught me the basic principles of loadlines, coupling, transformers and a whole lot more when I was a teenager.....  Click below for PDF files  WARNING!  The file sizes are large, despite conversion to .pdf format which reduced the jpeg scan files by a factor of more than 2.  This prompted me to break the book into sections.

Chapter 1 (1.6MB):  On distortion, load lines for triodes and pentodes, bias conditions, reactive loads and push-pull.

Chapters 2, 3, 4, 5 (1.5MB):  On instability, supply regulation, gain & resistor values (out-of-date!)

Chapters 6, 7, 8 (1.3MB):  On, hum, screening, noise & intermodulation.

Chapters 9,10 (2.2MB):  On input/output matching, damping, current & voltage feedback and impedance and output stage negative feedback.

Knowledge of the underlying principles is needed to make best use of the information,
especially basic AC theory and the concept of the equivalent circuit (Thevenin - voltage & Norton - current).
The best primer I have read on theory is Morgan Jones' Valve Amplifiers, pub. Newnes available from Amazon et al.  You can take or leave his actual designs but the presentation of the theoretical background is invaluable.

A series of articles by Norman Crowhurst were published by Glass Audio under
the Title "Audio Classroom".

Edward Dell has kindly granted me permission to publish these articles here.  It will be a lot of work so if you are interested, please be patient with me over the coming weeks and months.
V11 No6  Pt1,    Voltage amplifier stages on gain, frequency response, triode vs pentode characteristics and distortion.
V12 No1  Pt2,    The power stage
V12 No2  Pt3,     Phase inverters
V12 No3  Pt4a,   PP power stages
V12 No4  Pt4b    PP power stages
V12 No6  Pt5,     Feedback amplifiers
Jan 2001 Pt6a,   Special output circuits  (now Audio Express magazine)
Feb 2001 Pt6b   Special output circuits (also Audio Express)

These were published by Audio Amateur or E-mail
Audio Amateur is the best "one-stop" resource for literature.

The "Bible" is Langford Smith's Radiotron Designer's Handbook 4th Ed
available on CD rom.  However to start with Ed3 is much more readily
assimilated.  You will have to search for a copy of this though.

Another terrific resource for a tremendous bandwidth of audio related information is the Audio Cyclopedia by Howard M. Tremaine, Pub. Howard W. Sams.  The 2nd edition contains tube information.