Author Topic: Tube based Audio amplifiers - web page  (Read 553 times)

Offline Mars

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Tube based Audio amplifiers - web page
« on: May 24, 2018, 10:09:38 AM »
Hi All
I enjoyed this article. Do you find it informative?

http://www.gammaelectronics.xyz/vtaa_6.html
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Offline Family_Dog

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Re: Tube based Audio amplifiers - web page
« Reply #1 on: May 24, 2018, 01:08:24 PM »
Indeed, nice article!

Only briefly glanced through it, will read it later.

-F_D



-Eric

That Guy in South Africa...
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Offline Ampdog

Re: Tube based Audio amplifiers - web page
« Reply #2 on: May 25, 2018, 05:48:19 PM »
Ah - Yes!!

An excellent overview of the many designs hatching forth in the 50s - NOSTALGIA!

The main thing not mentioned (unless I missed it) is that the writer is Mr John Linsley-Hood, himself an eminent audio designer from England, from the previous century. Pleasant and informative reading and an eye-opener regarding what could be considered the start of high-fidelity equipment. Mr Linsley-Hood also pioneered a few simple transistor designs, some of which are still in use some 60 years later (obviously now with more modern transistors).

Apart from a few errors* this article is an authoritive piece of history, setting straight many misconceptions even in its brief coverage.

Note from me: The important British article "Amplifiers and Superlatives" by Williamson and Walker; Wireless World, Sept. 1952; is worth looking up by those wishing to be set straight regarding the U.L. debate.
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* Mainly, certain erroneous connections of the screen bypass capacitor from screen to earth, not cathode, of pentode stages (e.g. the Leak TL12 circuit and others).

Secondly: The detailed description of the Sonab amplifier more follows fig.17 than fig.16, particularly regarding the input circuit (some component values in fig. 16 are wrong).
Audio must be the only branch of engineering where lack of basics' knowledge is considered a superior form of wisdom. (Anon)

Offline Mars

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Offline Ampdog

Re: Tube based Audio amplifiers - web page
« Reply #4 on: May 31, 2018, 02:44:51 AM »
Yes thanks, Karel, that is it!

I advise all interested in hi-fi design to read it, if only to re-establish the basics of high fidelity design as very well stated by D.T.N. Williamson in the first part of the article. (Younger members will perhaps recall the writers as two of the few - the great men of hi-fi design and equipment.)

(and for academics, there are some nice, simple maths at the end!  ;D ;D ;D )
Audio must be the only branch of engineering where lack of basics' knowledge is considered a superior form of wisdom. (Anon)

Offline fredeb

Re: Tube based Audio amplifiers - web page
« Reply #5 on: June 01, 2018, 07:31:28 AM »
Thanks Karel and Ampdog !

Also good to hear a mention of JL Hood's name , here's a link to some of his SS work : http://www.angelfire.com/sd/paulkemble/sound3.html
...evolution is the gradual development and stratification of progressive series of wholes, stretching from the inorganic beginnings to the highest level of spiritual creation.
Jan Smuts

Offline Ampdog

Re: Tube based Audio amplifiers - web page
« Reply #6 on: June 05, 2018, 05:47:43 PM »
Mr Mars!

What are you setting in motion every now and then? 
;D ;D ;D ;D ;D

Rereading the reference you initially posted  .... How nice it would have been if us oldies (including you for the purpose of this post) could gather round a campfire with the necessary food and liquid substance and share friendly views of the days of excitement, when one's first one-valve radio (frequently oscillating job with tickler winding)  actually worked, from there progressing to something more risky (a full-fledged Mullard 5-20 and having touched the 450Vdc rail at least once)  >:(

Thanks for raising these bits of read from yesteryear, even if only to 'relocate' as it were, to what basics of good amplification was all about and times when one could not even spell 'trasnitser'.

'Good old days'? At least the necessary components were available from Hamrad and whatever stores featured in other centres. (I still have a tall 6L6G in a Ken-rad box marked '12/-')

Best wishes to all still dabbling in the winter-friendly glowing lamps!
Audio must be the only branch of engineering where lack of basics' knowledge is considered a superior form of wisdom. (Anon)

Offline John.Perry

Re: Tube based Audio amplifiers - web page
« Reply #7 on: June 05, 2018, 10:41:15 PM »
Those articles should be framed and appreciated as art!?