ASO Season to open with superstar pianist Andre Watts: concert also marks debut of new concert shell at Symphony Hall.

Patrons are in for a surprise when they arrive.

Over the summer, the company has quietly constructed a new, $500,000 stage shell, which will significantly affect the look and the sound of Symphony Hall. Anonymous donors picked up the tab. Concert stages routinely have some sort of box structure around and behind the stage, serving to project the sound out into the hall and make it easier for musicians to hear each other. The old shell was 45 years old.

The new shell, designed by a team of acoustic professionals, will change the looks of things, surrounding the orchestra with natural wood finishes instead of the former white paint. Whether this enhances Symphony Hall’s classic modernist decor is something we’ll all have to decide once we get a peek, but it should definitely improve the room’s notoriously dicey acoustics, especially in the lower frequencies.

There’s also a new piano in town. The orchestra recently accepted delivery of a Steinway Model D grand piano. The nine-foot piano, the largest Steinway makes, will join three other concert grands the orchestra owns. Like all pianists playing with the orchestra, Watts will be able to choose which one he prefers, so we might not hear the new piano this week.

Beethoven’s C-minor Concerto was first performed in 1803 with the composer playing the piano and conducting, and with only one day’s rehearsal for a program that also included the premiere of his Symphony No. 2 and of a major oratorio, with a reprise of his Symphony No. 1 thrown in for good measure. The program, which began at 6:30, continued for about two and one-half hours. Audiences liked to get their money’s worth back then. Some of the work looks back to the composer’s early, Haydn-influenced period, but it also foreshadows what was to come, including the dramatic intensity of his Symphony No. 5.

The first known review of the concerto included a statement that the work requires “a capable soloist who, in addition to everything one associates with virtuosity, has understanding in his head and a heart in his breast.” That seems an apt description of Watts. A regular guest here, he burst onto the music scene in 1963 when he was 16, propelled by Leonard Bernstein, who put him on a national telecast. He then substituted for ailing superstar Glenn Gould on short notice, and has performed internationally ever since. Of a recent performance, the New York Times said: “Even his quietest playing has a kind of swagger to it.”

The Bach suite is one of four by Johann Sebastian Bach. The term “suite” here refers to a type of dance piece with a prominent overture quite popular in the eighteenth century, and this one has five movements. The second of these, “Air,” is among the best known Baroque pieces in the repertoire today, and is often performed in transcriptions.

Brahms wrote four symphonies, and by the time he wrote his third, he was “50, and at the height of his powers,” as the ASO’s program annotator Ken Meltzer points out, adding that he was “very much his own man … creating music of extraordinary unity, concentration, and beauty.” Like the other two “B’s,” Brahms never seems to fall from favor. Still, this is the first time the ASO has performed the Third Symphony since 2008.

The new ASO season is an ambitious one. We’ll hear world premieres from four composers, beginning with a work from Atlanta’s Richard Prior, whose “…of shadow and light… (incantations for orchestra)” will be featured on Oct. 3-5. Guest artists include Yo-Yo Ma and Garrick Ohlsson.

Also new this season will be a series of five “First Friday” concerts. Like Beethoven’s concert featuring the concerto, these begin at 6:30. Unlike Beethoven’s, these will be kept to an hour including intermission, for those who like things early and short. The first of these is Nov. 1.