[Amps] stereo to mono

[Φραγκιαδάκης Παναγιώτης]

first i am sory for my bad english
second i am very huppy to find a nice place like that
fine
HELLO TO ALL
for sort you can call me frank
there are 2 problems
1) i want to bridge a stereo amplifier (solid state ) 2 apsoloutley seperrate chanels to one 
2) this one chanel i want to drive a modoulator transformer for anode modulation
QUESTIONS
a) eny schiematic for the bridge? (input and output) 
b) what way to modulate in order to protect the transistor ampifier 
c) eny schiematic for an audio (finall) amlifier with tubes push pull perhups??
 
DATA
1. stereo amplifier is 2x500 watts with to no cirquit of face shifting at the input
2. trnsmiter 2x 4-400 paralell at plate dc voltage 2,8 kv at 600 to700 ma
regards frank