The Baroque orchestra is the type of large ensemble for mixed instruments that existed during the Baroque Era of Western Classical music, commonly identified as 1600-1750. Baroque orchestras are typically much smaller, in terms of the number of performers, than Romantic music era orchestras from the 1800s. Baroque orchestras originated in France where Jean-Baptiste Lully added the newly re-designed hautbois (oboe) and transverse flutes to his vingt-quatre violons du Roy (this translates as "The twenty-four violins of the King"). As well as violins and woodwinds, the baroque orchestra contained basso continuo instruments such as the theorbo, lute, harpsichord and/or pipe organ.
In the Baroque period, the orchestra was not standardised in size. There were large differences in size, instrumentation and playing styles - and therefore orchestral soundscapes and palettes - between the various European regions. The 'Baroque orchestra' ranged from smaller orchestras (or ensembles) with one player per part, to larger scale orchestras with many players per part. Examples of the smaller variety were Bach's orchestras, for example in Koethen where he had access to an ensemble of up to 18 players. Examples of large scale Baroque orchestras would include Corelli's orchestra in Rome which ranged between 35 and 80 players for day-to-day performances, being enlarged to 150 players for special occasions.
The term 'Baroque orchestra' is commonly used in the 2010s to refer to chamber orchestras giving historically informed performances of baroque or classical on period Baroque instruments or replica instruments. The period-instrument revival during the 1970s inspired the development of the first period-instrument baroque orchestras, led by Nikolaus Harnoncourt, Gustav Leonhardt, Frans Bruggen and Terrence Holford.
Since the 1970s many baroque orchestras have been formed across Europe, as well as some in North America. Baroque orchestras active in the 2010s include: