The cellist Martin Lovett, who has died aged 93 after contracting Covid-19, acted as the musical conscience of the Amadeus String Quartet. When the playing of his three colleagues – all of whom were Austrian exiles – threatened to become too sweet, Lovett could be relied on to bring them back to the right side of good taste with a finely drawn phrase from his Stradivarius instrument.

Like Herman Busch, a player he deeply admired, of the Busch Quartet, Lovett displayed qualities that could be overlooked when set against the wayward genius of the leader, Norbert Brainin, the virtuosity of the violist, Peter Schidlof, and the solid accomplishment of the second violinist, Siegmund Nissel. And yet his very dependability, his quintessentially British avoidance of anything that smacked of showiness or gloss, made their own contributions to the quartet’s four decades of success.

One remembers how perfectly he could place even the most exposed of entries – the little questioning motif at the start of the Menuetto of Schubert’s A minor Quartet, or the opening phrase of Mozart’s D major Quintet, K593. Immediately, the scene was set for the more brilliant higher instruments to make their mark. He was partnered in Schubert’s C major Quintet by some illustrious fellow cellists – William Pleeth most often, but also Mstislav Rostropovich and Robert Cohen – without ever sounding second best.

Born in Stoke Newington, north London, Martin was the son of Sam Lovett, a professional cellist, and his wife, Leah (nee Rothenberg), both of whose Ukrainian parents had arrived from Russia in the 1890s. Sam’s father introduced his grandson to the violin, but from the age of 11 Martin was determined to follow Sam’s choice of instrument.

He was educated at schools in London, Leeds and Liverpool. In 1942, after several years of lessons with his father, he won a scholarship to the Royal College of Music in London. There he met his future wife Susi (Suzanne) Rozsa, a Hungarian-born violinist, and studied with Ivor James, a renown- ed authority on Beethoven.

After graduating in 1945, Lovett began to freelance, sometimes playing alongside Sam in the Hallé Orchestra in Manchester. He often participated in Max Rostal’s chamber orchestra – with not only Rozsa but the other future Amadeus members, and she introduced them to him. He heard Pablo Casals’ last concerts in Britain, played at Glyndebourne and – still in his teens – became principal cellist of the Sadler’s Wells Orchestra.

When what started as the Brainin Quartet first met to rehearse, early in 1947, “I was the baby of the group,” Lovett told the Jewish Chronicle. “They used to call me ‘the Benjamin’. I had to learn German quickly.” But he soon grew into his role and even by the time of the group’s London debut as the Amadeus Quartet in January 1948 the four or five years’ age difference had become immaterial. The programme consisted of Mozart, Beethoven and, at Lovett’s suggestion, the quartet by Verdi, a Busch speciality.

There was a great appetite for chamber music, encouraged by the new BBC Third Programme. The hitherto leading ensemble, the Griller Quartet, left Britain for a university residency in California, and the Amadeus’s extraordinary success soon made it possible for the four men to live on what they earned as a quartet. Teaching posts followed: they were resident at York University (1966-68); from 1978 they taught at the Musikhochschule in Cologne; and from 1986 at the Royal Academy in London. They recorded around 200 works, and the eventual Deutsche Grammophon collected set, starting from 1949 with early releases on the Westminster and Decca labels, runs to 70 CDs.

Lovett recalled their most remarkable concert as one that took place in Vienna in the late 1950s. “We were just coming on stage. The entire audience gave us a standing ovation. I thought, this is the town that threw out my Viennese colleagues when they were boys. Now this. It only happened once in our lives.”

Their repertoire was essentially Viennese, from Haydn to Brahms, but they found that they did not empathise with Schoenberg. Though they made occasional ventures into the 20th century, including quartets by Bartók, Britten and Tippett, Lovett told the New York Times that promoters were not interested in taking contemporary works from them.

In private life he displayed an almost military air that hid a personality of great warmth, modesty and integrity. He had a good sense of humour – essential for survival in the claustrophobic life of a quartet player – and liked going to the cinema. His fascination with gadgets and new technology combined with his love of jokes in some brief appearances on YouTube.

He had a keen analytical mind and could recall details of performances he had heard up to half a century before. Along with his fellow quartet members he was appointed OBE (1970) and received honours from Germany and Austria, and doctorates from the universities of York (1968) and London (1983).

Visitors to the Lovetts’ house in Hampstead saw some of his efforts as an amateur painter; his portrait of Schidlof was much admired. He and Susi were avid collectors of miniature violins.

After the dissolution of the Amadeus in 1987 on the death of Schidlof – Brainin died in 2005 and Nissel in 2008 – Lovett played in two piano trios and took part in various ad hoc ensembles for special occasions. He also taught, although even in his most frequent role, as a chamber coach – at the annual Cambridge symposium for young quartets or the Amadeus’s own summer schools – he was sometimes hampered by his lack of sympathy with much modern music.

Susi died in 2005 and in 2015 Lovett married the writer Dorinde van Oort. She survives him, along with Sonia and Peter, the children of his first marriage, five grandchildren and eight great-grandchildren.

• Martin Lovett, cellist, born 3 March 1927; died 29 April 2020