MUSIC

Nikolaus Lehnhoff, who created and produced the San Francisco Opera’s “Ring of the Nibelung” four years ago, has pulled out of the company’s planned 1990 revival of the Wagner cycle because of what he termed an unworkable rehearsal schedule. Lehnhoff, in a letter to company general director Lofti Mansouri, said the schedule made it impossible to achieve “even a blueprint” of the 1985 original production. The San Francisco Opera has booked four presentations of the four operas that make up the “Ring” next June and July. Mansouri said he would personally supervise the production team to mount the revival.