Timotheus in Harpers Dictionary of Classical Antiquities (1898)
A celebrated musician and poet of the later Athenian dithyramb. He was a native of Miletus, and the son of Thersander. He was born B.C. 446, and died in 357, in the ninetieth year of his age. He was at first unfortunate in his professional efforts. Even the Athenians, fond as they were of novelty, were offended at the bold innovations of Timotheus, and hissed his performance. On this occasion it is said that Euripides encouraged Timotheus by the prediction that he would soon have the theatres at his feet. This prediction appears to have been accomplished in the vast popularity which Timotheus afterwards enjoyed. He delighted in the most artificial and intricate forms of musical expression, and he used instrumental music, without a vocal accompaniment, to a greater extent than any previous composer. Perhaps the most important of his innovations, as the means of introducing all the others, was his addition to the number of the strings of the cithara, which he seems to have increased to eleven.
Timotheus of Miletus in Wikipedia
Timotheus of Miletus (c. 446-357 B.C.) was a Greek musician and dithyrambic poet. He added one or more strings to the lyre, whereby he incurred the displeasure of the Spartans and Athenians (E. Curtius, Hist of Greece, bk. v. ch. 2). He composed musical works of a mythological and historical character.
He spent some years in the court of Archelaus I of Macedon
Fragments in T. Bergk, Poetae lyriei graeci. A papyrus-fragment of his Persians (possibly the oldest Greek papyrus in existence), discovered at Abusir has been edited by U. von Wilamowitz-Mollendorff (1903), with discussion of the nome, metre, the number of strings of the lyre, date of the poet and fragment. See V. Strazzulla, Persiani di Eschilo ed il nomo di Timoteo (1904); S. Sudhaus in Rhein. Mus., iviii. (1903), p. 481; and T. Reinach and M. Croiset in Revue des etudes grecques, xvi. (1903), pp. 62, 323.