The 33 K in Nobukazu Shishido's DC amp....
Hi Everyone,
The 33K in the Shishido Loftin White "Rofton-White" amp ( apologies to Darius proponents, or... lets simply call it a two stage D-C triode amp !! ) acts as a one-part shunt regulator and it drops 4 or 5 mA. of current to ground.
It coincidentally also makes the Shishido 2A3 Rk a nice easy-to-obtain common / round number Ohmic value part. Do the math !
The 33 K shunt is "working" against the 1 mA. of current in the audio section ( both sections of the 12AX7, at 1/2 mA. each ).
A better implemention is to make the 33K higher in value, and make it a Mills MRA-12, shunting maybe 8 mA. to ground, against the B+ of the Shishido driver stage. Connect the R-Shunt Mills directly to ground and don't run the R-Shunt current through the 2A3 Rk !! Provides fabulous B+ stability. The new R-dropper value needs to be above 12K Ohms .
Cheers.
Jeff Medwin
Hi Everyone,
The 33K in the Shishido Loftin White "Rofton-White" amp ( apologies to Darius proponents, or... lets simply call it a two stage D-C triode amp !! ) acts as a one-part shunt regulator and it drops 4 or 5 mA. of current to ground.
It coincidentally also makes the Shishido 2A3 Rk a nice easy-to-obtain common / round number Ohmic value part. Do the math !
The 33 K shunt is "working" against the 1 mA. of current in the audio section ( both sections of the 12AX7, at 1/2 mA. each ).
A better implemention is to make the 33K higher in value, and make it a Mills MRA-12, shunting maybe 8 mA. to ground, against the B+ of the Shishido driver stage. Connect the R-Shunt Mills directly to ground and don't run the R-Shunt current through the 2A3 Rk !! Provides fabulous B+ stability. The new R-dropper value needs to be above 12K Ohms .
Cheers.
Jeff Medwin