WITH THE OBVIOUS exception of Joseph Haydn, Antonin Dvorak is probably the major well-known composer who has been most thoroughly "rediscovered" in the last 20 or 30 years. His tone poems and piano music were virtually unknown until as recently as that, and, while he was one of the most beloved composers, he was represented in general by less than a handful of major works - the one symphony, one concerto and one string quartet he composed in this country - and of course the Slavonic Dances. Now there is so much more Dvorak to love, and his string quartets constitute a major area of discovery.

Dvorak's quartets, like his symphonies, have been renumbered to accommodate the early works he left unpublished; while the six quartets thus added to the series are nice to have, at least an equal number of the previously published ones remain little-known to most listeners. All have been made available on records in a variety of performances by now, but the new cycle of the complete quartets being recorded by the Prague String Quartet for Deutsche Grammophon commands special attention: there have never been such incredibly persuasive performances of these works (or, for that matter, of many others, irrespective of category or composer).

This marvelous series began two years ago with the release of what is probably the greatest and is surely the most original of the Dvorak quartets, the magnificent G-major, Op. 106, formerly labeled No. 8, now No. 11 (DG 253.480). From the very opening phrase, the performance exudes a freshness and intensity that bring the work to life in a way that can only be called revelatory; the magic continues through all four movements, without a single prosaic bar.

Last year there was a similary glorious installment, pairing the familiar "American" Quartet in F, Op. 96 with the glowing Op. 105 in A-flat that brought Dvorak's sequence of 14 quartets to its close in 1895 (Op. 106 actually preceded it). Now we have two more gems, the early E-major, Op. 27 (sebsequently relabeled Op. 80 by Dvorak's publisher, who liked to do that sort of thing to make old works appear brand-new), and the mature Op. 51 in E-flat (2530.719).

The opening of Op. 51 is so beautifully realized in this performance that a reviewer can only be grateful for the limitation of space that saves him the embarrassment of demonstrating all too pointedly that is literally beyond words. Since both quartets are so rarely heard, this disc calls for an especially hearty recommendation.

The recorded sound on all three discs is more than first-rate; it is both rich and extremely well-balanced, a genuine enhancement to the magnificent performances. Now one only hopes DG will speed up its release schedule for the rest of this distinguished series and not stretch it out at the rate of only one disc a year.