In its heyday, the Budapest String Quartet, sensitive to the critical charge that its performances were just too perfect, had a policy to avoid too much practice. In order to keep a work fresh and an individual performance spontaneous, the four musicians consistently left a little something for the actual event.

When the subject was the late quartets of Beethoven, however, there was a sea change. No matter how many times they rehearsed these masterworks, there were always revelations for their highly trained ears, with nuances emerging from the shadows, beauty, power, heartbreak, and heroism born anew. Beethoven’s work assured the spontaneity of the concert; the trick was to try to communicate music that, increasingly, was written for the deaf man’s own cerebral and emotional development, the individual sonic moment almost an afterthought in an inner world of excruciatingly lovely and disturbing dumb show.

This week at the Mostly Mozart Festival, the St. Lawrence String Quartet is traversing these pieces in three installments, the first of which occurred late into Wednesday night at Lincoln Center’s Kaplan Penthouse. The quartet’s realization of the B flat major Quartet No. 13 was a noble effort.

The group (Geoff Nuttall and Scott St. John, violins; Daniel Panner, viola, and Christopher Costanza, cello) conceived of the work as somewhat brisker than the norm, setting right out in the Adagio ma non troppo-Allegro to establish a crisp, no-nonsense tempo. Especially considering that Mr. Panner is a substitute for regular violist Lesley Robertson, who is away on maternity leave, the foursome was exceptionally coordinated, with phrasing decisions that were well thought-out and rehearsed to a fine degree of precision.

The Presto was presto indeed; the quartet demonstrated fine dexterity and sophisticated yet humorous interplay. Except for some flatness in the first violin, the Alla danza movement was suitably charming.

The lack of a burnished or beautiful ensemble tone, however, kept the Cavatina — and, for that matter, this performance as a whole — from being top notch. Although the individual members have achieved an enviable blending, the resultant aggregate sound is far from the polished level necessary to communicate what is arguably the deepest movement in all of Beethoven. Still, the dedication of the fiddlers was palpable, and they made the most of what they had, employing vibrato sparingly but judiciously.

While making some pre-concert comments, one of the members of the group — I won’t identify him by name for fear that he might be shunned by the powerful local contemporary music establishment—mentioned that the Grosse Fuge that ends this quartet is much more modern sounding than Azul, the Osvaldo Golijov piece that was performed on opening night of this festival. Beethoven was cautioned against employing this last movement and eventually acquiesced to the pleadings of his friends to write a more pleasant, if much less meaty, finale. But the St. Lawrence really wanted to play this masterpiece, 740 measures of maniacal intensity, and did so thrillingly. Again the quartet’s tone was an issue — this time, not as a totality but as four rather strained voices. But their ardor compensated for a lot.