The future violist came to Australia as a child with his mother Margaret and aunt Jane in 1885. In 1887 Margaret married Charles Janssen. It is unclear if Stephen was adopted by him formally, but at least he took Charles' name. The family lived in Newcastle, New South Wales. From 1895 he was studying at the Sydney College of Music, among his teachers was H.G. Rivers Allpress. In 1903 at a SydneyCollege of Music examination he received a silver medal as first prize for an original piano composition. In April 1903 he departed for Europe. The farewell concert was held in Newcastle King's Hall and included some compositions of his own: the above-mentioned piano Romance and The Lifeboat. In May Vost Janssen arrived in London and attended the Handel Festival. He then studied violin, composition and orchestration at the Leipzig Conservatory Among other famous musicians he attended three concerts by 12-years old Mischa Elman. Though he contracted scarlet fever and was a patient in a hospital for two months, he received a flattering diploma. Returning to England, Vost Janssen became a member of the John Dunn's String Quartet. On 22 May 1905 he left England for Australia. On his voyages he had an opportunity to see a little of Naples and Genova. While in Europe he published two articles in his native Newcastle newspaper describing musical life in England and Leipzig. A vast review of his non-musical impressions was published a year later, after his return to the homeland.
After return to Australia
From September 1906 Vost Janssen gave invitation concerts. He had a prominent role in Sydney musical life of those years. One of his pupils from this period was David Burt, who on his insistence went to Germany in spring 1908 to study at the Leipzig Concervatorium. He subsequently won a three years' scholarship at that institute. In 1907 Vost Janssen was playing viola in Staell Quartet. Their first performance in Newcastle was on 13 March. By the middle of 1908 Staell left the ensemble and Francis Mowat Carter became the first violin. The second was given to Rudolph Brauer. The quartet was renamed to Sydney String Quartet. Around the same time was established the Sydney Madrigal Society. By summer 1909 Brauer left the ensemble, Vost Janssen replaced him as the second violin. The viola part was played by Nico Ornstein. Next summer Vost Janssen joined Cyril Monk's Austral String Quartet. With this and other combinations of prominent Sydney chamber players he participated in many concerts during next years. In November 1911 the violinist Francis Mowat-Carter went to Europe, what meant a loss of one of the most active musical life organizers. This was balanced by Alfred Hill's 1910 arrival to Sydney from New Zealand. For some time Vost Janssen was conductor of the Newcastle Operatic Society, but resigned this position during 1912-1913 season.
After NSW Conservatorium establishing
After the New South Wales Conservatorium was established in 1915 and Henri Verbrugghen came to Australia to be a director of it, the Austral String Quartet lost its importance, as Verbrugghen brought with himself a fine Verbrugghen String Quartet. Vost Janssen appeared in a quartet with James Hickey, Chas. Wentzel and Gladstone Bell, in which he played the first violin. Vost Janssen died suddenly at his residence in spring 1945.
