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Old 2nd January 2010, 12:39 PM   #1
Stee is offline Stee  Italy
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Default a complete accurate VAS with JFET and BJT

to have an accurate signal
in voltage amplification
you need a minimum Load in each step
so JFET also until +/-25V is a perfect sensor
see my idea from Hiagra schematic
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Last edited by Stee; 2nd January 2010 at 12:45 PM.
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Old 2nd January 2010, 01:38 PM   #2
Nrik is offline Nrik  Denmark
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I am currently experimenting with something like this. The sound is absolutely fantastic.
Check also Borbelys FET line stage - it is almost the same thing
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Last edited by Nrik; 2nd January 2010 at 01:43 PM.
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Old 2nd January 2010, 01:42 PM   #3
Nrik is offline Nrik  Denmark
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You need resistors in the sources of the second stage though.

Here is a working circuit:
http://www.borbelyaudio.com/adobe/borb502.pdf
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Old 2nd January 2010, 04:06 PM   #4
Stee is offline Stee  Italy
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Default Thanks a lot NriK

that is very intresting for me
Simplicity is the companion of beauty ...
so not like the cascode
do tou have a drawing of your best result?
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Old 2nd January 2010, 11:46 PM   #5
Nrik is offline Nrik  Denmark
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Quote:
Originally Posted by Stee View Post
do tou have a drawing of your best result?
I have not finished my experimenting, but until now it is very much like the second drawing in your first post, with 1k resistors in the sources of second stage.
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