I forget his name , but he was a good guy , i had sent him some schematics in the days when
the pultec schematics weren't common , hope he made out alright
passive as in , any pultec, where the eq " network " is a no gain loss type - passive -
[ which suffers about a 20db gain loss ] and needs an make up gain amplifier after the network
you might want to read up a little on the internet .
In the case of newer versions input transformer = balanced in , which becomes unbalanced feeding the network anyway
and unbalanced in = no transformer . Yes the transformer is passive , but passive in regards to pultec refers to the filter network
which has no gain or " Active " [ requiring power ] components .