The Class-A Amplifier Site

This site was last updated on 18 January 2007





The Class-A Amplifier Site



This site is primarily dedicated to the Class-A amplifier designed by John Linsley Hood, which was originally published in Wireless World in April 1969 (with a postscript in December 1970) and later updated in Electronics World in September 1996.  However, other Class-A design articles by Jean Hiraga, James Sugden, Stan Curtis and L Nelson-Jones have been added, along with some more JLH circuits. Schematics for other Class-A amplifiers and for three classic Class-B commercial amplifiers, the NAD3020, the Cyrus 1 and the Sugden A48-II, have been included for reference.





Last Updated

The JLH Class-A Amplifier


1 May 2004

Other JLH Amplifier Designs


12 January 2002

Other Class-A Amplifiers


19 July 2004

Classic Class-B Schematics


17 August 2003

JLH Power Amp Schematics


18 January 2007

The Published Articles of John Linsley Hood


18 January 2007


New pages and significant revisions will be indicated by having the ‘Last Updated’ column entry coloured red. This identification will remain for a period of about one month. Minor amendments to a page will be simply indicated by a change to the ‘Last Updated’ column. A summary of content changes, where appropriate, can be found in the ‘History’ at the bottom of each page.


All material that has been reproduced from the original articles is the copyright of the appropriate author and/or publisher.


This website is maintained by Geoff Moss. I can be contacted at:



01/05/2001 Site created

04/07/2003 Site closed

17/08/2003 Site re-opened with new URL

04/04/2004 Indexing revised

18/01/2007 JLH Power Amp Schematics added