Klaus Tennstedt's illuminating touch

Amid all the chatter about the ''sound'' of this or that orchestra, it's refreshing to hear a group that boasts no such brand-name identification. I am speaking of the London Philharmonic Orchestra, which, after a year under Klaus Tennstedt, has apparently been schooled to produce only the sounds required by the composer. At least, one heard precious little playing beyond the strict demands of the score during a recent concert at Symphony Hall here.

What one did hear was an almost transparently visionary Schubert Unfinished Symphony as well as a profoundly figured Mahler Fifth, for which Mr. Tennstedt has won a recording award.

The orchestra has just completed an extensive tour of the United States, and if the Boston stop was any indication, the performances brought convincing proof that Klaus Tennstedt knows how to shape an orchestra as well as how to lead one. Indications of the latter skills have come from numerous guest appearances with American orchestras, in which his depth and musical acumen have been much in evidence. This was the first time he could be heard with an orchestra that might rightfully be called his own, and the opportunity proved very illuminating, indeed.

The playing of the London Philharmonic demonstrated remarkable singleness of purpose and blending of sound. The sharp delineations and clear hues of the orchestra came across with remarkable clarity.

Tennstedt and his orchestra were also quite at home roaming through the large , complex metaphors of the Mahler Fifth. The piece held together with an inner rightness that can only come from mastering all the interlocking motions and complicated gestures of the piece. Detail is the name of that game, and Tennstedt played it like some fiendish chess master who knows all the moves in advance. In the meantime, the lengthy, discursive plot structure of the symphony was constantly before our eyes.

Tennstedt's stick technique, which seemed loose and understated in the Schubert, became positively riveting in the Mahler, cutting expertly through the choppiest and most troublesome passages. He followed the score like a Talmudic scholar observing every last punctuation of the law. But there was also a spaciousness here that all but took one's breath away.

This symphony, like many of Mahler's, offers many opportunities to go wrong and many more for the listener to lose interest. I not only never lost interest: I simply wanted them never to stop.