cheshirecats

Hi everyone. A few questions: (1) Regarding the input JFET (lsk389), what will be the best Idss (for reducing THD)? i.e. Shall we use lsk389a or b or c. I remember reading somewhere that larger Idss = less distortion, but then it's a bit strange that lsk389a is more expensive than lsk389b/c. (2) Can we use BF862 (lower noise, more available, higher gfs, lower ciss, higher idss) instead? Currently the gate resistor is 100ohm, so probably one shall increase it to 470ohm for BF862? (3) Can we reduce the gain of the amplifier? (since my DAC can output quite high levels (+24dBu), and I usually listen at low volume). Moreover, will this leads to lower THD? It will be great if someone can do a LTSpice simulation... Thanks.

Hi everyone. A few questions: (1) How shall Servo1 and Servo2 be used / connected? In particular, it seems the 5K ohm next to Servo1 is not connected. (2) Regarding the input JFET (lsk389), what will be the best Idss (for reducing THD)? i.e. Shall we use lsk389a or b or c. I remember reading somewhere that larger Idss = less distortion, but then it's strange that lsk389a is more expensive than lsk389b/c. Sorry if this is a silly question, as my analog circuits knowledge is quite poor. (3) Can we reduce the gain of the amplifier? (since my DAC can output quite high levels (+24dBu), and I usually listen at low volume) Moreover, will this leads to lower THD? It will be great if someone can do a LTSpice simulation... Thanks.