JFET/MOSFET complementary-differential preamplifier

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PMA
I think your pre amp looks great.
Interestingly I just built a pre amp that is similar ( based generally upon the borbelly line amp ) using J fets in a symmetrical differential at the input and with 2 mosfets at the output connected to the input in a similar way to the one you have choosen.
My measurement equipment will a lot more basic than yours but I seem to get lower overall distortion when I cascode the front end jfets.
I had not adjusted R1 or R2 but I have been adjusting Re. Have you found that adjusting R1/R2 instead of Re gves lower distortion?
 
Have you found that adjusting R1/R2 instead of Re gves lower distortion?

Hi AMV8,

yes, because the key is to keep input JFETs in the most linear portion of the transfer characteristic, and R1/R2 serve only to set appropriate Vgs bias of the output MOSFETs. For more info, please visit

Distortion in JFET input stage circuits

Regards,
 
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