These pages provide information on the designs developed by Jim Sugden in the 1960s and 1970s. In particular, they look at the details of the Class A power amplifiers he produced. The equipment covered has not been made or sold for many years. However Sugden Audio continue to exist and produce Class A audio amplifiers. If your interest is in modern Sugden amplifiers then you can click here to go to their company website.
In the UK ‘Sugden’ has become virtually a synonym for ‘Solid State Class A power amplifiers’. If you were a UK audio fan back in the 1960’s and 1970’s you will probably fondly remember various designs which appeared under the ‘J. E. Sugden’ brand name and ‘JES’ logo. Although some of the early designs lacked eye-appeal, their audio performance was exceptionally high. The amplifiers were also hand-made with care and attention. Jim Sugden can claim to be the person who introduced the first commercially available Class A solid state audio power amplifiers for Hi Fi use.
There has been a lot of controversy over who was the first to ‘invent’ - or more accurately - apply the use of Class A for high fidelity solid state audio power amplifiers. Back in the 1960s and early 1970s various people investigated the problems of the early transistor designs, and Class A was one solution that emerged. Although in one sense this was ‘back to the future’ as it reapplied older ideas, it was a break with the main trend in solid state amplifier design which used Class B or AB in various forms.
If you look back at the audio and electronics magazines of the period you can find articles on Class A amplifiers by various people. Also letters arguing the topic, and designs by well-known engineers like Linsley Hood. There was also apparently a claim by Hacker Radio that they were the first to introduce Class A solid state power amps. The truth is that many people and firms were involved in the process of identifying the problems and devising solutions. However, now that the dust has settled on the early arguments, it seems clear that the first Class A transistor power amps made and sold on a commercial basis for use in Hi Fi systems were those designed by Jim Sugden. The links below examine the evolution of the early designs.
1967. Jim Sugden, and the Si402.
1968. Richard Allen Class A amplifiers.
1968. The J. E. Sugden and Co A21.
1969. The A21 ‘Series 2’.
1969. The C41 and A41 pre/power amp combination.
Click here to see some photos of early versions of the JES A21 amplifier.
My thanks to Sugden Audio for their help, and for the information they kindly supplied to make these pages possible.
If you have any colour photos or other information on the early Sugden amplifiers, or the company that made them, please get in touch. I plan to add more pages to this website and more information would be welcome. You can contact me via the email address given at the bottom of my main AudioMisc website page which you can reach by clicking on the icon, below.