On 27 September 1983, Sri Chinmoy began playing the cello in Puerto Rico.
The cello became one of Sri Chinmoy's favourite instruments and he would often play the cello in Peace Concerts, both as instrumental and accompanied with voice. These two recordings are for the Paris Peace Concert in 1984.
Cello with Singing
Cello with vocal accompaniment, recorded at the same concert.
Cello Performance
Cello instrumental, recorded at the Paris Peace Concert, Espace Balard, 13 October 1984.
Pablo Cassals

It was also in Puerto Rico that Sri Chinmoy met the renowned cellist Pablo Casals. See: Meeting at Sri Chinmoy Library
Sri Chinmoy recounts the meeting
I met Maestro Pablo Casals in Puerto Rico. He was on the wrong side of ninety, and I had perhaps scarcely crossed the barrier of forty. I was quite young. I still had a considerable amount of hair!...
At that time I had never thought of playing the cello. He said, “Do you want to hear a piece? I will play a piece by Bach.”
He was an expert, a real expert — a maestro of the highest order. He started playing, and I was listening most devotedly, with deep feeling. He wanted to play another piece, so he played and I appreciated him....
One or two years after his departure from the earth-scene, Pablo Casals started coming from the soul’s world when I gave Peace Concerts. He would sit always facing me, about a metre away, when I was playing. He would meditate very deeply.
(excerpts) Sri Chinmoy, My Golden Children, Agni Press, New York, 2013.
Early experiments
Despite not taking the cello as a serious instrument until 1983, Sri Chinmoy recorded an album in 1975. "Sri Chinmoy Plays the Cello: 1"

Recorded in 1975. It was re-released in 1993 and 2006. See: Radio Sri Chinmoy
Cello in Peace Concerts
Sri Chinmoy playing the cello, 26 May 2005.
Sri Chinmoy playing the cello, Milan, 28 May 2005.
Sri Chinmoy plays the Cello at Borobodur, 25 December 2005.
Listen to Cello performance from Borobudur.
Cello Albums

Cello - Victory's Dance-Smile. Improvisations on the cello (1985)

Sri Chinmoy Plays the Cello (1975. Re-released 1993, 2006)

Maestro Sri Chinmoy - Cello and Sanskrit chants (2005)
Writings on the Cello
Question: I wanted to ask if there is a certain spiritual quality that the cello embodies. Recently you gave two concerts on Long Island and I felt a lot of power and intensity when you were playing the cello.
Sri Chinmoy: Truth to tell, I am not satisfied with my cello performance. If your consciousness goes high while I am playing the cello, I give all the credit to you, all the credit! When your consciousness goes high, anything that you see in front of you will give you tremendous joy. I give full credit to you, not to the player in me. The higher we go, the better we experience the reality. Do you understand? As a cellist I am not satisfied with my standard. But if you like my cello performance, it is because of your consciousness. I am serious when I say this.
In the cello world, the maestro of maestros is Pablo Casals. In the very evening of his life we met together in Puerto Rico. As soon as he saw me, tears started rolling down his cheeks. They fell on my shoulder. With such joy he was telling me, "You have come at the very evening of my life." Then he played two pieces for me from Bach. His cello playing was sublime.
Another experience I am telling you about my cello. I gave a performance at the Royal Albert Hall in England. Among my disciples, there was someone who could not appreciate my cello performance. As good luck would have it, a member of the audience came up to that person after the concert and said, "How long has Sri Chinmoy been playing?"
The disciple answered, "Three years."
"Three years? I have been playing for seventeen years," that musician said, "but he plays better than I do!"
To that particular disciple who could not appreciate my cello performance, a real cellist came. And he was saying I played better than he did!
Last year I lifted a very famous cellist. His comment was that if I learnt the proper technique, I would enjoy the cello better. To be frank, I only like my cello at one time and that is when I sing my song for Lord Buddha. If my voice is in good condition, that is the only time I like my cello.
The cellist
We have a new disciple who plays the cello with the Puerto Rico Symphony. She also has about 50 students and teaches five or six hours daily. One by one her students come and play in front of her. When her good students come, she gives them five minutes. When the bad students come, after a minute she says, “Oh, you are playing very well. I am pleased with you.” Then she sends them away immediately.
I wanted to practise the cello while I was in Puerto Rico, but this new disciple did not want to let me play on her cello. But after she refused, then for the whole day she felt totally miserable. So on her own she brought me her cello the next day. She said her cello cost $5,000. It was good, but mine is better. She herself was supposed to play that day, so she borrowed a cello from somebody else.
When I tried her cello she flattered me, saying that my intonation was good. That is why she allowed me to use it.
The day I was supposed to return the cello, I told her to come at twelve o’clock and take it back. She came exactly at twelve. I had brought her a trophy, and she said, “Can I not also have a plaque to put on this trophy that says you gave it to me?”
After I returned the cello, she told Alo that she felt some higher power was guiding her hand when she played it. When she played she felt that it sounded as if Pablo Casals were playing. So she was very happy that she had let me use it.
— 19 February 1984
Sri Chinmoy, The World-Experience-Tree-Climber, Part 3, Agni Press, New York, 1993