The choice of musical instruments is an important part of the principle of historically informed performance. Musical instruments have evolved over time, and instruments that were in use in earlier periods of history were often quite different from their modern equivalents. Many other instruments have fallen out of use, having been replaced by newer tools for creating music. For example, prior to the emergence of the modern violin, other bowed stringed instruments such as the rebec or the viol were in common use. The existence of ancient instruments in museum collections has helped musicologists to understand how the different design, tuning and tone of instruments may have affected earlier performance practice. As well as a research tool, historic instruments have an active role in the practice of historically informed performance. Modern instrumentalists who aim to recreate a historic sound often use modern reproductions of period instruments (and occasionally original instruments) on the basis that this will deliver a musical performance that is thought to be historically faithful to the original work, as the original composer would have heard it. For example, a modern music ensemble staging a performance of music by Johann Sebastian Bach may play reproduction Baroque violins instead of modern instruments in an attempt to create the sound of a 17th-century Baroque orchestra. This has led to the revival of musical instruments that had entirely fallen out of use, and to a reconsideration of the role and structure of instruments also used in current practice. Orchestras and ensembles who are noted for their use of period instruments in performances include the Taverner Consort and Players (directed by Andrew Parrott), the Academy of Ancient Music (Christopher Hogwood), The English Concert (Trevor Pinnock), the Hanover Band, the English Baroque Soloists (Sir John Eliot Gardiner), Musica Antiqua Köln (Reinhard Goebel), La Chapelle Royale (Philippe Herreweghe), the Australian Brandenburg Orchestra, and the Freiburger Barockorchester. As the scope of historically informed performance has expanded to encompass the works of the Romantic era, the specific sound of 19th-century instruments has increasingly been recognised in the HIP movement, and period instruments orchestras such as Gardiner's Orchestre Révolutionnaire et Romantique have emerged. A variety of once obsolete keyboard instruments such as the clavichord and the harpsichord have been revived, as they have particular importance in the performance of Early music. Before the evolution of the symphony orchestra led by a conductor, Renaissance and Baroque orchestras were commonly directed from the harpsichord; the director would lead by playing continuo, which would provide a steady, harmonic structure upon which the other instrumentalists would embellish their parts.