Kingston
Well-known member
I have recently learned the basic usage of tube load lines when setting up a common cathode triode stage. I bumped into the fact that I must select plate resistor about 2-5 times the value of internal plate resistance of tube for desired gain and impedance.
http://www.aikenamps.com/CommonCathode.htm
With some tubes it's difficult to get low THD and low output impedance without ridiculously high B+, so one (expensive) choice is to use a plate choke to replace the plate resistor. As far as I understood plate now sits at B+ (or near) since there's no voltage drop from Rp.
How does this affect the usage of tube load lines, since they assume a plate resistor? Where do I fit the choke into the calculations in the link above, and how to bias the tube with it?
Thanks,
Mike
http://www.aikenamps.com/CommonCathode.htm
With some tubes it's difficult to get low THD and low output impedance without ridiculously high B+, so one (expensive) choice is to use a plate choke to replace the plate resistor. As far as I understood plate now sits at B+ (or near) since there's no voltage drop from Rp.
How does this affect the usage of tube load lines, since they assume a plate resistor? Where do I fit the choke into the calculations in the link above, and how to bias the tube with it?
Thanks,
Mike