A question for you:
Using 10V zener diode in series with the main PS voltage for a single-ended amp, say a 6L6, and the current is 40ma.
Under this situation the zener would have an equivalent resistance of 250 ohms (10V/250ohms = 40ma)
Q: Does the zener have the same ripple reduction as a 250ohm resistor when there is another cap afterwards?
Using 10V zener diode in series with the main PS voltage for a single-ended amp, say a 6L6, and the current is 40ma.
Under this situation the zener would have an equivalent resistance of 250 ohms (10V/250ohms = 40ma)
Q: Does the zener have the same ripple reduction as a 250ohm resistor when there is another cap afterwards?
No, the ripple would be higher amplitude and less 'rounded', in other words more harmonic content... more triangular shaped.
10V, 1W Zener 1N4740 has a dynamic impedance of 7 Ohms at 25 mA - for 40 mA around the same - would give the ripple reduction of a 7 Ohm resistor.