In article ,
Patrick Turner wrote:
Quad-II used a kind of floating paraphase. Nobody much understands
exactly how it works but fact is that the output of one EF86 is
reduced
by resistance divider and fed to the grid of another EF86 and both
thus have a stage which effectively has 6dB of local positive FB. Both
EF86 have to make up to about 40Vrms for each KT66 grid, ( depending
on the load ).
It's not really that hard to figure out how it works, a lot of the quirkiness is
due to the acrobatics needed to apply negative feedback to the common cathode of
the voltage amplifier and phase splitter. This was probably a bean counter
thing to eliminate a couple of electrolytic capacitors.
--
Regards,
John Byrns
Surf my web pages at,
http://fmamradios.com/