In Reply to: Re: ? for MSL about PP "iron" for 12 W. pentodes. posted by MQracing on May 14, 2004 at 18:32:12:
EL821 = 6CH6 is a 12 W. pentode. The EL821 will work with EL84 "iron", but Ra is higher. The EL821 is more sensitive than the EL84 and max. Ua is 275 V.
What I've got in mind is PP "finals" employing Dennis Boyle's combination bias. The smallish unbypassed cathode resistor raises the O/P impedance. That's why I'm thinking in terms of a 10 KOhm CT primary.
BTW, a KEY virtue of the EL821 is price. A matched quad of NOS Mullard EL821s is about $100.