A delightful surprise often awaits New York Philharmonic staff and musicians who climb the Avery Fisher Hall backstage stairwell: Principal Cello Carter Brey, sitting on the second-floor landing, practicing Bach. "That's when my colleagues come and give me those indulgent smiles," Brey jokes.

He has been practicing there in preparation for his March 27 and April 1 performances of Bach's complete Suites for Unaccompanied Cello at Holy Trinity Lutheran Church ("the stairwell is the closest I can get to the church's acoustic") during The Bach Variations: A Philharmonic Festival.

"I have to confide that, when the Philharmonic asked me if I'd like to do this Bach marathon, my first reaction was, 'Would I really buy a ticket to hear myself play these pieces in one sitting?'" Brey says. "As I thought about it more, I decided that I could justify it if I brought something to it that would challenge me."

That something, he decided, would be performing Bach in a historically informed manner. For the occasion he will play on a cello outfitted in the style of a Baroque instrument, complete with gut strings (yes, made out of animal intestine), a convex Baroque bow, a stubby wooden end-button (replacing the modern instrument's long metal endpin that balances the cello on the floor), and a special bridge, tailpiece, and sound-post.

Brey first began experimenting with a Baroque setup ten years ago after attending a production of Bach's St. Matthew Passion performed on period instruments at the Brooklyn Academy of Music. "By the end of the evening, I wanted to see if I could do that myself," he recalls. "I realized I could learn a tremendous amount by embracing the early-music movement instead of treating it derisively, as many do."

This cellist feels that the Fourth Suite in particular benefits from being played on a Baroque-style cello. He describes it as the "quirkiest" in the set: it's in E-fl at major, a key in which Brey says no cellist likes to play, and he describes the movements as "awkward," "ridiculous," and "un-cellistic." "I didn't arrive at an approach that satisfied me until I started playing it on a Baroque instrument, and then I realized that I could take a lute-like approach."

However, it is the suite's very awkwardness that charms Brey. "I'm always striving to put my finger on exactly what mind-set Bach was trying to project. He knew it was a perverse key to ask a cellist to play in : I think he was having a little fun at the cellist's expense."

Brey is synesthetic, and he intuitively associates colors with keys. The Fifth Suite is in C minor, which for Brey conjures up the color black, and his descriptions of the suite's movements are appropriately grim: "The first movement grabs you by the throat and doesn't let you go. There's high tragedy in the Allemande. The Sarabande is like tombstones, completely bereft of any comfort. And the Gigue is like a death-dance." The Sixth and final Suite is in D major, which Brey sees as golden yellow: "I think of sunshine pouring through the window."

Violinmaker James McKean has constructed two cellos that Brey will use in the concert: one with a Baroque setup, the other, a five-stringed cello for the Sixth Suite, as Bach originally intended. McKean clarifies that he did not make a Baroque cello, but rather worked to support Brey's musical goals by providing "a contemporary instrument for a musician who wants to incorporate Baroque practice," McKean explains. "I want to make what Carter hears in his head audible to the audience." William Monical, one of the world's foremost authorities on Baroque instruments, advised Brey and set up the cellos McKean made.

Carter Brey's fi rst musical heroes were pianists: his father was an amateur pianist with a musical ear and a substantial library of piano recordings. Carter first picked up the cello at age 12 and began private lessons at 16. It was then that he learned Bach's First Cello Suite. "It seemed supremely difficult, like climbing Mt. Everest," he says. Still, Brey believes that his early saturation with piano led him to approach cello as a pianist, hearing counterpoint and harmonies rather than focusing on melodies. This mind-set serves him well when performing Bach's music as the composer : a noted keyboardist : would have heard it. Because the Baroque bow makes it easy to highlight key notes in the underlying harmonies, Brey approaches the suites as though he's playing two instruments at once: one that plays a melody and the other, a bass line.

This will be the cellist's first time performing Bach's Unaccompanied Suites in one sitting : a two-plus-hour endeavor : and he says his preparations are not unlike how he trained for three New York City Marathons: "It's about extending your ability to do something extraordinary without hurting yourself." However, for the audience, he wants the experience to be as comfortable as possible. "I want them to look forward to it, like going to have a nice meal. "To sum up, I'm taking myself on a challenging trip and inviting people to come along. I hope they enjoy it half as much as I do."

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Elana Estrin, the Publications and Content Editor at the New York Philharmonic, has written on music in The Strad, The Huffington Post, The Jerusalem Post, and other publications.