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Old 27th May 2021, 3:38 pm   #24
Jez1234
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Join Date: Mar 2021
Location: Morpeth, Northumberland, UK.
Posts: 936
Default Re: Advice on this linestage build

Quote:
Originally Posted by Robert Gribnau View Post
Hello Jez,

I did not ask you for free R & D service. I asked you because I could not believe you can achieve a gain of 400 with an EF86 or an EF184 at line level.

From your reaction I now understand that additional circuitry is needed. But even than I still find it hard to believe. But hey, I am just an amateur.

About the distortion of an EF86 strapped as a triode: I find it hard to understand that an EE in audio and a Chief engineer at a (now defunct) hi fi company, like you wrote you are, needs to prove to himself that those claims were false. Furthermore I do not know of any Svetlana datasheet that claimes 0,1 % at 10 V output for an EF86 in triode mode but if you say so, it must be out there somewhere.
Well lookie here... seems I have my first troll on vintage radio.net

It is easy to achieve gain of 400 from many pentodes. No "additional circuitry" is needed. Just a high value anode resistor and no appreciable load on it.

The Svetlana web site seems to be defunct. They are now made by a different supplier and just branded Svetlana and it seems they have gone to quite some lengths to remove all links to original datasheets etc and the current datasheet I can find is different from the original one... however here is a link to the relevant information, originally on page two of the datasheet http://users.telenet.be/tony.de.lobelle/toon/

<0.05% @ 10V RMS actually claimed.
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