The JLH Gateway

Professori

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Apr 15, 2018
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Location
Trivandrum, Kerala, India
Good morning friends,

John Linsley Hood is a name that needs no introduction in this Forum, and the mention of the 'JLH amp' is likely to trigger sweet memories in the hearts of old timers, as well as enthuse quite a few newbies who had built and enjoyed the iconic Class-A amplifier designed by the master.

The original design, published in the April, 1969, issue of the UK magazine Wireless World, has been a hot topic of discussion in forums like DIYAUDIO and today one of the oldest threads there is approaching 10,000 posts! The fact is that the timeless design by JLH is able to hold its own despite the passage of more than 50 years, and that too in the face of technical advancements made in the last half century. Even today the JLH Class-A amp maintains its popularity among audiophiles who prize subjective quality more than anything else, and today the Gen-Z too (whose keen ears do not belong to the last century!) have developed a love for the classic design.

Unfortunately the discussion threads in various Forums have become humongous, and trawling them for relevant information has become a truly uphill task. Not only that, many sites that offered handholding for the JLH enthusiast and hosted rare archival information are dead now. This leaves the DIYer pretty high and dry.

For some time I have been planning a Golden Jubilee Tribute to the master designer JLH. But the pandemic and other engagements stole my free time. Thankfully I have been able to cull most of the necessary information from my own PC backups as well as from various sources, online and otherwise. My intent is to offer a tribute to the Master, while at the same time offer a "single window" experience for the JLH enthusiast and the ardent DIYer. I have gathered the information in a series of Blog posts, which I am sure would be of interest to most of our members. Here is the first post in the series:


Kindly read, follow, comment and share... more than that, do build and enjoy!

Warm regards
-- UKP
 
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The JLH Gateway Part-3:


Do follow and share and comment ... and enjoy!
PS:
Kindly note that the research and the writing and editing is somewhat time and effort intensive, if we are to be authoritative and factual. Part-4 draft is not yet complete. Will post as soon as it is ready. Do comment about anything ...positive or otherwise... ;-) Do also feel free to point out any errors or omissions.
Thank you for your patience and love.
 
The JLH Gateway Part-4:


Here is the update on the JLH Gateway, with the 1996 version of the Classic 1969 amplifier. Do read and plan your build.
Your love and support makes me love the labour!
 
Thank you sir @Professori for the links. Along with JLH, Jean Hiraga and of recent times, Nelson Pass, Dr. Bora Jagodic come to mind. Am sure many more such illustrious sorts have made their mark/ contribution in some way or the other, over the decades. All in the pursuit of sonic bliss! Regards
 
Certainly true... I haven't forgotten those greats!
In a future post I am planning to include those class-A designs that are similar to the JLH Classic, but by other designers like Nelson-Jones, Dr Jagodic, Mr Diego (The DLH) etc and a few other not so well known designers. Your suggestions and contributions for inclusion are most welcome.

Jean Hiraga already is well-documented elsewhere, and for the PLH amplifier one needs to point the browser at the Passdiy site.
Thanks and regards.
 
I have taken a minor decision regarding the huge number of articles published by JLH in his lifetime. In order to avoid confusion, ALL the material related to the 'Simple Class-A Amplifier' (Wireless World, April 1969), updates by JLH, other updates and mods by Geoff Moss and others, build notes and mods, Forum notes etc will be posted in the JLH Gateway. (Linked above)

As for the rest of the voluminous stuff, not easily accessible on the Web, I am planning to create a new Blog with commentary and links to virtually the entire corpus of material published by JLH in his lifetime on various technical journals. Unfortunately a small number of papers remain inaccessible, which might be remedied in the future with the help of Forum members here or elsewhere. Permit me to post the first link here. As you can guess, it is a not a simple work, and surely "work in progress". Please make maximum use of the authentic archives presented there.


Do read and enjoy, share and comment!
Warm regards
 
Dear Members,
I have some happy news to share with you. Mr Elliot of ESP has very kindly included a link to my blog JLH Gateway in the Class-A amplifier page (re-hosting of the material originally hosted by Geoff Moss ).


Warm regards,
-- UKP
 
Hi,
I too am a HUGE Fan of JLH and had avidly read all his original articles, as soon as they were published.
I still have with me, most of the Original Wireless World magazines containing JLH's and other audio articles.
Happy to share, good quality scanned pdf files of the JLH Class A amplifier & subsequent article for its regulated power supply. Any one interested, please DM Me your E-Mail.
Also available here.

Incidentally, JLH did visit India, and I'm told holidayed with friends at Malabar Hill, Mumbai... :)
 
Dear Members,
I have some happy news to share with you. Mr Elliot of ESP has very kindly included a link to my blog JLH Gateway in the Class-A amplifier page (re-hosting of the material originally hosted by Geoff Moss ).


Warm regards,
-- UKP
This is an EXCELLENT Site... Have been using it for years
 
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JLH Memorabilia Part-3:


A really looong post ... and I haven't covered even half of the 1980s ...
Do read and enjoy, and embark on a few new builds -- frankly, there are few current designs to match those by JLH in real-world sound quality!
Warm regards.
-- UKP
 
The DLH amplifier is REALLY a FLEA Power amplifier: (Unlike the JHL from which it has taken 'inspiration' )
"The output power in pure class A operation is 15.52 W at 2 ohms (@ 1 KHz), or 7.76 W at 4 ohms, or 3.88 W at 8 ohms. "

The ESP amp, Also 'inspired' by the JLH, despite several years of hindsight, apparently does not match up the JLH, as the author confirms "I dare say that in sound signature too the DoZ is very near to the JLH Classic."
 
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