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Original Message
D3a vs 417A
Posted by Tube_Maniac on March 17, 2017 at 07:07:23:
Hello!
What if this circuit replacing with D3a (wired in triode), I know the output impedance should be high without any buffer stage and line output transformer. What is the output impedance can you think of?
Should we adopt the 110 ohm cathode resistor value from Andrea Ciuffoli headphone amplifier design?
http://www.audiodesignguide.com/NewHeadphoneAmp/sch1.gif
What is the plate load resistor?? The B+ is 180v.