2. "You don't try to make the concert be just like the last rehearsal," says Donald Weilerstein. "It's something more. Rehearsing gives you the security to do something different in the actual concert."

Above Don and Martha Katz, meditating moments before a Cleveland Quartet concert, are as seperate as they can be. Quartet members seem to fascinate people, who watch avidly for signs of a rift, and the Clevelanders are a little defensive on this point, especially since Martha the violist and Paul Katz the cellist are married to each other.ST"There's all this thing about the Budapest Quartet not knowing each other," comments Paul. "But it's pretty relative. When you rehearse together eight, nine hours a day and do 100 concerts a year, and when you all live in (See QUARTET 2, F2, Col. 1) Rochester as we do, and teach at the Eastman School of Music, and when you add in the business meetings and recording sessions and receptions and all, well, when you come down to breakfast in the hotel coffee shop, maybe you'd rather sit by yourself and not see one another till we land. That doesn't mean we're not geting along."

All four are married, but there are no children. They're all in their mid - 30s, and music has dominated their lives from childhood. Even before their debut in 1969 at the Marlboro, Vt., festival, their paths had crossed at Juilliard and Aspen and other places, and the Katses had played in two university quartets.

After Marlboro they moved immediately into residence at the Cleveland Institute for two years, then shifted to Buffalo for five years with the state university before settling into the Eastman residency.

"There was none of this freelancing in New York and oracticing nights," Paul says. "A residency gives you a chance to get in some solid work."

The first year in Cleveland they practiced together six hours a day, plus of course the three or four hours of solitary practice, which gave them little time for concerts but developed them quickly as a group.

Lately they have got the group rehearsals down to three hours a day, but now there are the tours of Europe and South America to worry about.And the recording sessions, which go nine hours at a crack : one movement of one quartet played over and over for maybe three hours.

From the beginning there was a sense of excitement and personal fufillment. The very first thing they played together was a Haydh quartet, and the sound of it thrilled them all.

Paul : "A member of a famous quartet came up tp us after Marlboro and said we were going to be great. I was shocked. I said it'd be fine to be okay. But he said, no, you're going to be great. I was quite taken aback."