YOUNG Simon Rattle, all of 27 by now, has not been a conductor to bother with trifles in building up his discography. Following a stunning Mahler Tenth, a somewhat less persuasive but still impressive account of "The Planets" and a Sibelius Fifth which some of my colleagues liked more than I did (seemed pokey and self-conscious to me), Rattle has tackled Janacek's unique and magnificent Glagolitic Mass, which, like the other items mentioned here, has been recorded digitally by EMI/Angel (DS-37847).

Rattle's full understanding of the idiom is beyond question. The City of Birmingham Symphony Orchestra and Chorus, the quartet of British soloists (Felicity Palmer, soprano; Ameral Gunson, contralto; John Mitchinson, tenor; Malcolm King, bass) and organist Jane Parker-Smith all respond to his galvanic direction with both fervor and polish. The convincing, handsomely recorded performance comes with splendid annotation by Robin Golding as well as the full old Slavonic text.

Fine as Rattle's performance is in its own right, though, it strikes me as just a bit "homogenized" in comparison with the two other recordings of the work available now. The greater excitement in the one conducted by Rafael Kubelik (DG 138954) may be offset by its rather dated sonics, but the recent Supraphon issue, recorded in Janacek's own city of Brno under Frantisek Jilek (1112.26998G), not only gives us an earthier, more exultant realization of the score but is a quite vivid analog recording, perhaps even a little more full-bodied than the new Angel.

On a new Supraphon disc (1110.2840G), Jilek and his Brno State Philharmonic offer a most welcome collection of four Janacek works that have not been available for some time. Side 1 is taken up by the unaccountably neglected "Lachian Dances"; on side 2 are the tone poems "The Fiddler's Child" and "Ballad of Blanik" and the overture "Jealously."

This collection supersedes an identical one available a few years ago in performances by the same orchestra under Jiri Waldhans. The new performances compare favorably with those, the sound is much more realistic and, most important, it is simply good to have this music available again.

Another Janacek disc not listed in Schwann is an eminently serviceable Musical Heritage Society issue on which Karl Ludwig Nicol conducts the Baden Chamber Orchestra in two very early works for string orchestra, the Suite of 1877 and the "Idyll" of 1878 (MHS 3165). It comes up for reconsideration now against Nonesuch's new digital release of the "Idyll" and the wind sextet called "Mladi" ("Youth"), both played by members of the Los Angeles Chamber Orchestra under Gerard Schwarz (D-79033).

While a conductor has not been considered necessary in earlier presentations of "Mladi," it must be said that both of these performances are first rate--surely among the very finest things we've had from this source. If the coupling looks attractive, this is a very safe bet; and since the Suite is available on Neville Marriner's Argo disc of the Suk String Serenade (ZRG 792) Schwarz should get the nod for the "Idyll" over Nicol on MHS.

It should be pointed out, though, that Marriner's performance of the adorable Serenade composed by Suk at the age of 18 is marred by his rushing of the final movement. Many collectors may have the more satisfying recording by Karl Muenchinger on a recently deleted London disc or may prefer to wait hopefully for its reappearance in the Stereo Treasury Series. (Copies might still be around in cut-out bins--London CS-6737). Those who do opt for Muenchinger in the Suk will want to avoid duplication by choosing Nicol on MHS for the Suite and the "Idyll" and will enjoy the Prague Wind Quintet's performance of "Mladi" on Supraphon 1.11.1177, with wind sextets by Bohuslav Martinu and Miloslav Kabelac.