[Amps] 811A's & Bias

[edw3nr@nexband.com (Ed)]

Is it really necessary to have operating bias on 811A's ? If so, is 4.5 
to 5 volts a good value ? Can a string of 2 to 3 amp rectifier diodes be 
used instead of a Zener ? I am currently using a 47 ohm resistor from 
grid to ground on each tube (4) and am not sure this the right way to go 
about it. Any ideas and/or comments. Thanks....73

Ed W3NR