Rudolf Serkin is on another concert tour of the country. That of itself is not exactly newsworthy, perhaps, even though the esteemed pianist has already passed his 80th birthday season and is still going strong. The program he is exploring this year (heard at Carnegie Hall last Wednesday) features a work with which he has long been identified - Beethoven's ''Diabelli Variations.'' In fact, for some aficionados, no one else has managed to plumb the depths of this profound work quite as probingly as Serkin.
Encountering the ''Diabelli'' in a Serkin concert has not exactly been hard to manage this past decade. For now, when he chooses to tour, a few works that particularly engage the artistic explorer in him are always bound to show up, hence the ''Diabelli'' again this season, the Reger Variations two seasons back, etc.
So why does one keep going back to Serkin? Surely it is not for the thrill of superior virtuosics: Even when he was in fullest command of his fingers, Serkin was never acclaimed for his note-perfect playing. Does he conjure astounding tones from the keyboard - limpid, melting lyricism, thunderous resonances, gossamer filigree? Well, yes. But he does such things only when the music demands. Serkin never does something beautiful just for beauty's sake: Every aspect of his playing is at the service of the piece at hand.
The ''Thirty-three Variations on a Waltz by Anton Diabelli'' begins innocently enough, yet in Serkin's vision, the waltz is already something more like a peasant Landler - propulsively put forth with clog-stomping vigor. From there, Serkin slips us into Beethoven's ever more engrossing, visionary world of the last piano sonatas and string quartets. There are pages, as played by Serkin , that clearly hint at things to come - Schubert, Schumann, Chopin. All of this is communicated as theme-and-variations, a form that - not too long before Beethoven stretched it to such dimensions - had existed principally as an enchanting device to showcase a fleet technique, as well as a gift for improvisation and an engaging ability to entertain an audience.
Serkin's all-Beethoven program also included a somewhat tenuous account of the 24th sonata, Op. 78, and a more-than-usually imprecise, yet often beguiling, ''Les Adieux'' (No. 26, Op. 81a). One could argue that one goes to hear moments from Serkin nowadays, but his ''Diabelli'' disproved that notion.
If you can't hear him this season, you might want to sample the Beethoven piano concerto cycle he has now completed for Telarc records (with Seiji Ozawa and the Boston Symphony, in sumptuous recorded sound). Or else you might want to wait for the CBS Masterworks release of his new recording of the aforementioned Reger Variations. And one of the finest performances of the Schubert opus-posthumous B-flat major sonata on records is the one included in his 75th Birthday recital (CBS M2-34596), recorded live at Carnegie Hall.
Grant Johannesen is celebrating the 40th anniversary of his New York debut this season. In matters of programming, his Alice Tully Hall recital last October was both a Johannesen sampler and a darned good program as well. Forty years of experience and living with the music flooded out of his account of the Schumann Fantasy in C major, Op. 17. Clarity of voicings, sensitivity to the various lines, and a firm sense of restraint pervaded his Bach Fantasy and Fugue in A minor, demonstrating that, in the right sort of hands, Bach on a modern piano is perfectly valid.
Roy Harris's Sonata amply satisfied the American-music factor (how few American artists ever bother with our music on their programs). Delectable Poulenc (''Theme Varie'') and surprisingly uninteresting Roussel (''Trois Pieces''), as well as Liszt's transcriptions of six of Beethoven's ''Goethe Lieder,'' completed the shrewd, captivating program. Overall, one could savor the ardent simplicity of his playing, the deft way he handled long lyric lines, and throughout, the ear acutely attuned to subtle color changes.
All the marks of a master craftsman in full control of his craft were on display, which is as it should be for such a landmark event.
Alicia de Larrocha
Alicia de Larrocha has carved a special niche for herself in the later part of her career. For years, she doggedly kept at a career that was noticed only by aficionados, and then, mostly for her definitive performances in her native Spanish music. But suddenly, first in New York, then around the world, others began to take notice, and she began to show her rapidly swelling audiences that she was as equally at home in Chopin and Schumann as in Falla or Granados.
At the New York Philharmonic, she decided to perform two pieces she has recorded to great success, yet ones that oh-so-rarely appear on a live program: Falla's ''Nights in the Gardens of Spain'' and Franck's ''Symphonic Variations.''
With a more sympathetic conductor, Miss de Larrocha would have had a triumphant time with the Falla. Her new London recording (410 289-1) with Rafael Fruhbeck de Burgos and the London Philharmonic is a particularly bewitching performance.
At the Philharmonic, Andrew Davis seemed to think he was conducting Brahms or Mahler, rather than an evocative, soft-grained tone poem. Thus Miss de Larrocha had to devote all her energies to merely being heard.
But the Franck found her in top form, in a piece where the conductor is forced to take a subservient role. Here, the passage work flashed out brilliantly, the lines were spun with haunting effectiveness, the colors and blends were refined and superbly gauged.
It takes a great artist to make the Franck really take wing, and Miss de Larrocha offered about as fine a performance of it as one is ever apt to encounter in a concert hall.