Hi there,
I have a kit of class a preamp/headamp. Good price. Good sound.
http://serwis.avt.pl/manuals/AVT2464.pdf
Questions - how to decrease gain? Short one 15ohm should give 2x gain instead of 3x, right?
How to replace first IRF530 with 2sk170? is there a sense?
I have a kit of class a preamp/headamp. Good price. Good sound.
http://serwis.avt.pl/manuals/AVT2464.pdf
Questions - how to decrease gain? Short one 15ohm should give 2x gain instead of 3x, right?
How to replace first IRF530 with 2sk170? is there a sense?
to decrease gain - increase R6 , rebias first stage
or , to preserve same Iq through input mosfet , increase value of R6 and decrease value of R3-R4-R5 group in same amount , then rebias
gain is roughly ratio of (R3+R4+R5)/R6
I wouldn't bother with JFet instead of mosfet , at least not with simple swap , simply because gain stage with simple JFet , without NFB , is pretty close to clipping state,when nowadays line level is on input
or , to preserve same Iq through input mosfet , increase value of R6 and decrease value of R3-R4-R5 group in same amount , then rebias
gain is roughly ratio of (R3+R4+R5)/R6
I wouldn't bother with JFet instead of mosfet , at least not with simple swap , simply because gain stage with simple JFet , without NFB , is pretty close to clipping state,when nowadays line level is on input
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