These notes include all of Bach's concertos that have come down to us, except for concertos for a keyboard instrument without accompaniment and surviving fragments of concertos.

By Bach's time, coffee was so well established as a popular vice that it had spawned coffeehouses all over Europe.  Leipzig had several, but the proprietor of Zimmermann's Coffeehouse on the Catherinenstraße deserves our special gratitude for having had good taste not only in coffee but also in music.  From 1720 until his death in 1741, he hosted concerts of the Collegium Musicum, an ensemble of professional and university musicians, in his coffeehouse on Friday evenings during the winter and in his coffee garden on Wednesday afternoons during the summer.  Bach took over direction of the Collegium in 1729 and provided music for the ensemble and directed its concerts for over a decade. 

For his Collegium programs, which were the closest he ever came to giving public concerts, Bach created, among other works, nearly all of his harpsichord concertos.  In doing so, he essentially invented the idea of the solo keyboard concerto, the harpsichord having traditionally been an accompanist when playing with other instruments.  (Only in the fifth Brandenburg Concerto had he experimented with the harpsichord as a soloist.)  But the works themselves were not original compositions.  All of Bach's solo and multiple harpsichord concertos, except for one double concerto in C major, are thought to be transcriptions of earlier works that were originally written for violin, oboe or other instruments.  Of these earlier concertos, only three have survived, two concertos for violin and one for two violins, all of which have also come down to us in harpsichord transcriptions.  But Bach undoubtedly wrote more concertos during that earlier time that are now lost.  A good number of those are known only through their later transcriptions into harpsichord concertos.  In a few cases, Bach would also use a concerto movement in a sinfonia or aria in a cantata, giving us what is presumably an intermediate version, as well. 

In making a harpsichord version of a concerto for violin or some other single-line instrument, Bach altered many details, some of them in order to fit the new solo instrument, but some of them may also reflect his later thoughts about an earlier work.  Among other things, he needed to provide parts for the left hand, and for this, he sometimes doubled the continuo bass, but he also frequently added new material.  In certain passages, he changed idiomatic violin writing into passage work that would fit better under the hands of a keyboard player.  He also often added ornamentation in the harpsichord version.  And typically, he would transpose a violin concerto down a whole step to bring the solo part into the compass of a keyboard.

Harpsichord Concerto in D minor, BWV 1052

This concerto, Bach's best known harpsichord concerto, is thought to be a transcription by him of a lost concerto from his years in Cöthen (1717-1723).  The original was probably for violin, and there have been several hypothetical reconstructions made of a violin version.  The earliest version that has actually survived, however, appears in two cantatas that date from later in the 1720's: Cantata 146 for the first two movements and Cantata 188 for the third.  These cantata versions are for organ solo accompanied by an ensemble that is expanded to include oboes.  The concerto then reappears as a harpsichord concerto in the mid-1730's in a manuscript written out in part by Carl Philipp Emanuel Bach.  In that form, it was probably played by either Philipp Emanuel or by his father in concerts with the Collegium Musicum that Johann Sebastian was directing.  Finally, there is a copy of this concerto in Bach's own hand in a collection of all of his solo harpsichord concertos that he copied out in the late 1730's. 

The concerto opens with a powerful, jagged theme played as a ritornello by all the instruments in octaves.  In this virtuosic movement, the harpsichord's driving sixteenth notes culminate in a dramatic cadenza leading to the return of that opening ritornello to end the movement.  The slow movement is an Adagio in G minor.  It begins with a twelve-bar ground bass that continues throughout, as the soloist plays a florid melody over it.  With the third movement, the concerto returns to the forceful driving rhythmic character of the opening.  Here too the solo harpsichord part builds climactically to a brief cadenza before the closing ritornello.

This D minor concerto was performed a number of times (on the piano) during the nineteenth century, including by Mendelssohn, and it attracted the interest of many musicians.  After its publication in the mid-nineteenth century, Brahms wrote a cadenza for the last movement. 

Harpsichord Concerto in E Major, BWV 1053

Like the D minor concerto, this concerto in E major is thought to stem from a lost original from Bach's Cöthen years, and it too then appears in cantatas as a piece for solo organ with ensemble before being turned into a harpsichord concerto.  The lost original is thought probably to have been for violin or oboe -- unless, as has been suggested, the cantata version might actually be its original form.  In its organ version, the first movement is the opening sinfonia of Cantata 169, and the second movement is an organ obbligato in an alto aria in that same cantata.  The third movement is the opening sinfonia of Cantata 49.  Both cantatas date from 1726.  The harpsichord version, like Bach's other harpsichord concertos, dates from the 1730's and would presumably have been created for the composer or one of his sons to play with the Collegium Musicum in Leipzig.

This sparkling work is one of the biggest and most difficult of Bach's harpsichord concertos.  In its outer movements, he elaborates on the organ part to make the most of the brilliant sound of the harpsichord.  This is particularly true in the last movement, where he fills out the simple eighth-note motive at the beginning with fast arpeggios on the harpsichord.  Also in that movement, he speeds up and elaborates the sixteenth notes of the organ version with triplets for the harpsichord.  The middle movement is a beautiful, pulsing Siciliano in C# minor.  Here he elaborates on the organ version, adding ornamentation and dotted rhythms for the harpsichord and giving it gently flowing arpeggios to support the string ritornello at the beginning and end.

Harpsichord Concerto in D Major, BWV 1054

This Concerto in D Major is a reworking of Bach's Concerto in E Major for violin (BWV 1042).  As was his habit in adapting violin concertos for the harpsichord, he transposed the work down a step, adapted the continuo bass of the strings for the left hand of the harpsichord, and rewrote some of the figuration and ornaments to achieve the kind of brilliance on the harpsichord that the original has on the violin.  In the first movement, Bach adds a surprising thirty-second-note scale for the harpsichord to swoop down into its first solo passage.  In the third movement rondo, one middle section with virtuosic sixteenth-note double stops for the violin is translated into sixteenth-note triplets to give the harpsichord an equally brilliant sound. 

Some changes may raise questions for performers.  In measures 23 and 24 of the slow movement, for example, the slurred sixteenth notes of the violin are altered to dotted Lombardic rhythms for the harpsichord.  Did Bach feel here that he needed to enliven the decaying sound of the harpsichord with a sharper rhythm, or did he add this rhythmic ornament because he was rethinking the music as he revisited it a decade later?  Some violinists adopt this dotted rhythm from the harpsichord version, along with a few other minor alterations, while some play the passages as originally written.

Harpsichord Concerto in A Major, BWV 1055

This happy work, one of Bach's shorter concertos, is believed to be based on an earlier concerto that has been lost.  A reconstruction of a hypothetical original version for oboe d'amore in the same key of A major has been performed and recorded, although other possible solo instruments have also been suggested.  In addition to adding new material in the left hand of the harpsichord, Bach has presumably also elaborated some of the figuration in the solo part to suit the harpsichord.  Conspicuous among these adaptations are the bright harpsichord arpeggios added to the opening ritornello of the first movement and some of the fast figuration in the final Allegro.  The middle movement is a Larghetto in 12/8 with a flowing, lyrical line in the  right hand of the harpsichord.           

Harpsichord Concerto in F minor, BWV 1056

This short concerto is believed to be a transcription of a lost original concerto in G minor for violin or oboe.  The extraordinarily beautiful second movement appears as the introductory sinfonia to Cantata 156, where it is for oboe solo with strings and continuo.  In this harpsichord version, that movement has considerably more ornamentation in its melodic line, and it has the strings playing pizzicato, which better balances the plucked sound of the harpsichord.

Harpsichord Concerto in G minor, BWV 1058

This is Bach's later reworking of his Violin Concerto in A minor, BWV 1041.  As with all his transcriptions of violin concertos, the work is transposed down a step for the harpsichord.  Here a good deal of independent material is added in the left hand of the harpsichord, and some of the violin figuration is altered to lie more comfortably on the keyboard.  The latter is particularly noticeable toward the end of the third movement, where the harpsichord figuration lacks some of the virtuosic flair of the violin's string crossings.  In the middle movement, where the opening motive is in the bass, the harpsichord has a written-out continuo part that doubles the chords in the string accompaniment.

Triple Concerto in A minor for Harpsichord, Flute, and Violin, BWV 1044

Unlike Bach's other concertos, this triple concerto is a pastiche of music from two of his earlier works, neither of which is a concerto.  The first and third movements are adaptations of an early harpsichord prelude and fugue in A minor (BWV 894), a piece that Bach wrote sometime before 1717, during his years in Weimar.  The middle movement, an Adagio, adapts material from the slow movement of an organ sonata in D minor (BWV 527), which itself is thought possibly to be based on a lost trio sonata. 

The concerto is believed to date from sometime after 1729, when Bach was providing music for the concerts of his Collegium Musicum in Leipzig.  But with the outer movements based on such an early work, it feels somewhat less concise and focused than his other concertos that are based on more mature works.  The score calls for the same three soloists as the fifth Brandenburg Concerto, and the accompanying ensemble differs from that work only in that the ripieno ensemble of the Brandenburg Concerto has no second violin.

Concerto in F Major for harpsichord and two recorders, BWV 1057

This Concerto in F Major is Bach's later reworking of his Brandenburg Concerto No. 4.  The original Brandenburg being a concerto in G major for violin and two recorders, Bach has here substituted a harpsichord for the violin soloist and transposed the piece down a step to F, a key that not only fits the range of the keyboard but that also is more comfortable for the recorders.  In writing this harpsichord part, Bach has added interesting new material to the Brandenburg original, such as the long trill and waltz-like continuo chords at the beginning.  In the second movement, most of the material from the original violin and recorder parts is played by the harpsichord alone, as the recorders simply become part of the tutti ensemble.  The new chromatic ending to this movement is a fascinating example of how Bach was constantly rethinking old material.  In the fast passagework of the last movement, he converts the notoriously tricky violin figuration to equivalently tricky but equally effective harpsichord figuration.  Like his other harpsichord concertos, this adaptation of Brandenburg Concerto No. 4 dates from the 1730's and would have been written for the concerts of Bach's Collegium Musicum.