(b London, 15 May 1778; d London, 24 Aug 1829). English organist, pianist and conductor. He was taught the rudiments of music by his father, an amateur violinist. When seven years old he had lessons in singing from Robert Willoughby, a well-known chorus singer, and became a chorister at Portland Chapel. At eight he learned to play the harpsichord, which he then studied, together with the organ, under William Shrubsole, organist of Spa Fields Chapel, and Matthew Cooke, organist of St George's, Bloomsbury. In 1788 he became organist of Salem Chapel, Soho, and just over a year later he was appointed organist of Carlisle Chapel, Kennington Lane. Towards the end of 1790 he moved to Bentinck Chapel, Lisson Green, where he remained until December 1794, when the Rev. Rowland Hill invited him to become organist at Surrey Chapel. In 1796 he studied harmony under Samuel Arnold and he became a member of the Royal Society of Musicians in 1799. In 1800 he conducted a series of oratorios given under the direction of Bartleman in Cross Street, Hatton Garden. Jacob's compositions comprise songs, canzonets and glees; he also published two collections of sacred music (A Collection of Hymn Tunes … composed for the use of the Surrey Chapel, 2 vols. (London, ) and National Psalmody (London, c1815) as well as arrangements.
Jacob achieved a distinguished reputation as an organist, and from 1808, in association with Samuel Wesley and Crotch, he gave a series of organ recitals at Surrey Chapel. The programmes included airs, choruses and fugues by J.S. Bach, without any interspersion of vocal pieces. During 1808–9 Samuel Wesley addressed to him, as to a kindred spirit and a member (together with Vincent Novello) of the ‘Sebastian Squad’, a remarkable series of letters concerning Bach.
In 1825 Jacob left Surrey Chapel for the newly erected church of St John's, Waterloo Road. This led to a dispute between him and Hill, resulting in A Statement of Facts relating to the Expulsion of Mr Jacob from the Organ of Surrey Chapel (London, 1825), in which the musician triumphed over the divine.