In the 1980s, Peter Gelb produced 25 Metropolitan Opera broadcasts for PBS. Now, as the Met’s general manager, he runs the red-carpeted center of the opera world. The first media guy to run the hallowed New York institution has begun an ambitious but carefully modulated makeover of the Met. He’s putting its operas on more media platforms than ever before but using electronic media to reproduce the gilded in-theater experience. He’s bringing in a new breed of directors for fresh staging but relying largely on the beloved music of the past.Hired two years ago, Gelb was off to a running start in August when he took charge.