I have a new JFET/MOSFET complementary-differential preamplifier, please visit
PRE complementary-differential preamplifier
and see the attached images.
PRE complementary-differential preamplifier
and see the attached images.
Attachments
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?
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?
picture in 1st post shows 2sk389/2sj109.
more info on his website.
mlloyd1
more info on his website.
mlloyd1
Do you use monolithic JFET or matching by hand?
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,
Do you use monolithic JFET or matching by hand?
Both. The 2SK389/2SJ109 are very difficult to purchase, in fact almost impossible. For this reason, there is a PCB design for 2SK170/2SJ74, and the devices are hand-matched.
Regards,
Both. The 2SK389/2SJ109 are very difficult to purchase, in fact almost impossible.
Why do not you, constructs from inaccessible parts?
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