The Concerto Grosso is a type of orchestra or chamber music that pits a small group of soloists, known as soli or concertino (Italian), against a larger group of players called tutti or ripieno. The tutti consists mainly of strings and basso continuo but may contain woodwinds and brass in larger ensembles. The concertino or soli are set apart by their smaller numbers and virtuosic style of playing. Terraced dynamics, i.e., sudden changes from forte to piano, result as musical materials are passed between the soli and tutti.
Michel de la Barre and Other Musicians, c. 1710 | André Bouys (1656-1740) | The National Gallery
The concerto grosso typically has multiple movements that contrast in tempo and character, usually three movements in a fast-slow-fast tempo format. A movement is a self-contained section of a larger musical composition. It usually sounds complete enough to stand alone but is normally performed in a sequence of three or four movements.
The outer two movements of the concerto grosso are normally in ritornello form. The ritornello is the principle theme and is played by the tutti after each soli episode, often in abbreviated form and contrasting keys. In other words, the ritnornello behaves like a chorus or refrain, returning with the same theme each time. Here's a typical organization of the ritnornello form:
tutti | soli | tutti | soli | tutti | soli | tutti
The form of the concerto grosso's second movement varies but is usually slow and lyrical, often in ternary or binary form.
Academia Musical de los instrumento | Pablo Minguet | Madrid c. 1754
Brandenburg Concerto No. 5
Johann Sebastian Bach (1685-1750) is recognized as one of the world's greatest composers due to the unprecedented perfection he brought to most musical genres of the time. His Brandenburg Concerto No. 5 is one of the finest examples of a concerto grosso, and at twenty-five minutes, also one of the longest! This work was written in 1721 for the Margrave of Brandenburg while Bach was employed by the Prince of Anhalt.
The first movement, at ten minutes, is lengthy compared to concerto grosso by Vivaldi and Corelli. It's in ritornello form and has a concertino (soli) consisting of flute, violin and harpsichord. The ritnornello is introduced straight away by the string section. Listen to the ritnornello carefully so you can recognize reappearances after soli sections:
After the ritornello (tutti) statement, the first soli section ensues and the two groups, tutti and soli, alternate back and forth. Towards the last third of the movement soloists begin dropping out, leaving a solitary harpsichord to play a rollicking solo before the final forte ritnornello kicks in. A virtuosic solo in a concerto is called a cadenza. Cadenzas can be written out but they were often improvised on the spot, especially if the player was also the composer.
Brandenburg Concerto No. 5 BWV 1050 | Johann Sebastian Bach (1685-1750) | First Movement: Allegro | Listening Outline