RE: John's cartoon voice, that voice that you ever-so-perceptively recognize
(although not from Hanna-Barbera cartoons) is the versatile Paul Frees.  You
would certainly remember him for his work on most of the Jay Ward cartoons,
particularly as Boris Badenov, and as many (and I mean MANY) characters in
all of the Fractured Fairy Tales and similar Ward cartoons.

Brioohs