F6 Amplifier

Official Court Jester
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small signal xformers aren't made , usually , for passing any sort of DC ......... if they are , they aren't small no more :rofl:

so - regarding needs of biasing those bloody gates , xformer would see between 2V5-3V (depending what value of Rs Papa chose ) so ......... you can freely expect some cap in series with each secondary

that was the case always and always will be

we all know that Papa like Silmics and their sonic signature ;) , so prepare ..... ok - you tell me which value is cunnin' to have there ?

as example of olde times - lookielookie (also as confirmation of Papa's words that amp is pure classic ) - so two pics of pure golden classics

on one of them you'll see clever way of avoiding caps ...... but that's also having some other penalties , so my - as always humble - thinking is that using cap is still most prominent way of doing it
 

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Official Court Jester
Joined 2003
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don't look at that , as example worth here too much - currents are way too high for our case ...... due to less demanding control electrode ( base vs. gate ) we can make it more elegant

everything is , say , double duty there - small resistors are shunting secondary and biasing base of bjt in same time ; 400R is creeping current through small resistors , shunting secondary too

I posted that schm as example , where even feedback path is of same logic as in F6 (you can ignore Q13 in series with primary)

betchya that we'll find few more caps in F6, across pots in bias nets ; Papa seeded way too much simple machines around , and each of them is containing trick or two

puzzles , puzzles everywhere ........
 
Official Court Jester
Joined 2003
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well - I had impression previously - when he first time mentioned F6 - that he'll share that .

dunno - now , when you wrote that , I'm not sure - didn't asked ....... :confused:

whatever - enough info is here , along with already shown bits and pieces how to bias SJEP in simple way

I'm excluded from game , too much of insider info , tnx to my resident spy in PL cousine :mad:
 
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Official Court Jester
Joined 2003
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luckily , his quirks are heading to simplest possible solutions , lately

after deciding how to bias outputs , all one needs is to play with few variations for Rs , and few possible feedback amounts

I wouldn't choose M2-J2 biasing arrangement here ; it's possible with highish Rs , which I'll try to avoid

(just my opinion , not result of spy cam capture , situated in FW facility :devily: )