CLASSICAL MUSIC.

ORPHEUS CHAMBER ORCHESTRA -- Virtuosos from the conductorless chamber ensemble offer music by two friends--Brahms (the First Serenade) and Dvorak (the Notturno)--in a lunchtime concert at Trinity Church. (Broadway at Wall St. Sept. 1 at 1. No tickets required.)

BARGEMUSIC -- The young Swedish pianist Niklas Sivelov is in residence at the barge this weekend. Sept. 1-2 at 7:30: A solo recital of music by Haydn (the Sonata No. 47 in B Minor), Schumann (the Sonata No. 2 in G Minor), Scriabin, and Ginastera. Sept. 3 at 7:30 and Sept. 4 at 4: Beethoven's two Op. 70 piano trios (including the "Ghost," in D Major) surround Sivelov's "New York Trio," in a program given with the violinist Mark Peskanov and the cellist Sophie Shao. (Fulton Ferry Landing, Brooklyn. 718-624-2083.)

MUSIC AT ST. PATRICK'S CATHEDRAL -- Ross Wood, the associate organist of Boston's Episcopal Church of the Advent, continues the cathedral's long tradition of free organ recitals with a program of music by Bach (the Prelude and Fugue in A Major, BWV 536), Louis Vierne (movements from the Second and Fourth Symphonies), and Louis Marchland. (Fifth Ave. at 50th St. Sept. 4 at 4:30. No tickets required.)

OUT OF TOWN

BERKSHIRE OPERA -- Sari Gruber, the first-prize winner of this year's Naumburg International Vocal Competition, leads the cast of Donizetti's "L'Elisir d'Amore," the company's final production of the season. Kathleen Kelly conducts. (Koussevitzky Arts Center, Berkshire Community College, Pittsfield, Mass. 413-442-0099. Aug. 31 and Sept. 2 at 8.)

SKANEATELES FESTIVAL -- Twenty-five years ago, David and Louise Robinson decided that the Finger Lakes region needed some first-rate summer chamber music. Their festival, named for the lake on which their house sits (concerts are occasionally offered on the spacious porch), has maintained a small-town feel even while attracting world-class talent. Sept. 1 at 8: The violinist Hilary Hahn, a beloved figure at the festival who has played there since the age of twelve, joins several esteemed colleagues (including the violist Lesley Robertson and the pianist Natalie Zhu) in works by Piazzolla, Debussy ("Danse Sacree et Danse Profane," for harp and strings), Beethoven, and Enescu (the Violin Sonata No. 3). Sept. 2 at 8: Robertson joins with the pianist Elinor Freer, the cellist David Ying, and other musicians for chamber music by Lutoslawski, Bizet (a suite from "Carmen"), and Brahms (the Piano Quintet in F Minor). Sept. 3 at 8: In the final concert of the summer, Hahn joins the festival orchestra in Sibelius's Violin Concerto; Peter Bay, the conductor, also leads music by Ravel ("Le Tombeau de Couperin") and Dvorak (the "Czech Suite"). (Skaneateles, N.Y. 315-685-7418. For more information, see www.skanfest.org.)

CONCERTS AT TANNERY POND -- Christian Steiner's musical fiefdom, ensconced in an acoustically splendid Shaker tannery, continues ...