What distinguishes the Violin Concerto in D minor from its sister works is the decidedly virtuoso flavour of the solo part, which has to resolve such exacting violin techniques as arpeggios spreading over two octaves, bariolage figures (changing from open strings and stopped tones), broken intervals in semiqtuavers and rapidly changing double-stopping. In addition to indications construed from the autograph of the harpsichord version, it was primarily these violin performance practice figures which gave a clear idea of the original design of the work. The first movement is particularly conspicuous for its outstanding unisonal theme which, because of its thrice repeated syncopation accumulation and varied immanent harmony, was regarded as a bold invention for that period. The close interlinking of tutti passages (ritornellos) and solo parts - this is specifically achieved by the tutti parts (ripieno parts) accompanying the soloist in the solo episodes with segments of the ritornello theme - makes the movement a text book example of Bach`s art of motif work.
The second movement (Adagio) is to a large extent marked by the ritornello theme in G minor, which again is performed unisono. It is present in every bar of the movement as "basso quasi ostinato” (entirely within the meaning of the centre movements of the violin concertos in A minor and E major), thus lending it an elegiac basic mood only occasionally brightened by the arioso counter part of the solo violin. As opposed to this, the final movement with its insistent ritornello theme, the driving force of which is even enhanced by a dynamic contrast resulting from thin-textured sequences. develops lively contrapuntal play. The alternation from dialogue-style and extensive soloist passages makes it seem like the essence of “concert playing", encompassing in equal degree both collaboration and competition.
As with the D minor concerto, the keyboard (harpsichord) concerto in F minor leaves no doubts about its original existence as a violin concerto, and what is more, in G minor. The fact that only the violin can be regarded as the original solo instrument is evident from typical violin passages in the harpsichord descant, which to start with was designed with the open G string in mind, as well as from other violinistic performance figures which cannot be reproduced on the harpsichord with the same effect. That G minor instead of F minor was the original key of the concerto is apparent, among other things, from unusual voice leading, which can only be explained by transposition from G minor to F minor. Bach evidently saw himself compelled to transpose the keyboard version due to the fact that the original violin part (tonal range g to e-fllat"’) exceeded the tonal range of the harpsichord (highest note normally d"). The three movements of the work, which greatly differ with regard to manner and content, could be interpreted as the musical representation of different temperaments. The first movement in the main draws its effect from the contrast between the sedate ritornello theme (with its insistent repetition of rhythmic and melodic flourishes) and the lively triplet motion of the solo part. The Largo on the other hand with its wideranging melodic arcs is more inclined to display romantic traits. As opposed to this, the concluding movement marked "Presto" is markedly ill-humoured in temperament. expressing itself in the spirited ritornello theme, in an almost complementary rhythmic semiquaver movement, in the playful imitation of pithy motifs, in sweeping alternating figures and dramatic question and answer passages. There is every indication that Bach did not insert the centre movement until arranging the harpsichord version; the original centre movement has therefore been lost. Thus, in the interest of musical practice the New Bach Edition has taken over the Largo of the keyboard version transposed to B-flat major and transcribed for violin in the reconstructed form.
It can be concluded from various pointers that a Concerto for Oboe d'amore must have been the model for the Keyboard Concerto in A major. To start with the only keyboard alternating figures. i. e. arpeggios in the ritornellos of the first movement, were not supplemented until the rearrangement was carried out. according to clues in the autograph. Similarly the richly ornamented form of the solo part was incorporated only in the source of work on the keyboard version. Originally Bach had written a comparatively simple melodic line which, evidently because of its many sustained notes, seemed to him to be unsuitable for the harpsichord, and which he therefore replaced with an ornamental variant. There is even more evidence that the first version of the Larghetto was a melody instrument, and in fact an oboe d’amore, namely on account of the tonal range from a to b" (as is revealed when eliminating all the other ingredients of the arrangement). Also in support of this instrument is the cantabile style and the technique of the solo episodes, which frequently hint at cantata arias with soloist oboe d`amore. The A major Concerto draws its especial flair not only from the seldom played solo instrument, but also the alternating shape of the themes. Of Bach's mainly linear conceived themes, the ritornello theme of the first movement is distinguished by its triad broken chords, each of which leads in the third bar to gradual melodic continuation. Just as unusual as the wide-ranging leaping melody of the centre movement, which represents an effective counterpoint to the chromatic downward bass line, is the ritornello theme of the final movement, whose demisemiquaver runs extend over a tonal range of two octaves. In this case, what points to Bach is less the themes than the manner of the arrangement which, especially in the first and third movements, is essentially characterised by the motif connection between tutti sections and accompanying parts within the solo parts.
The music world has long since been aware of the fact that, in addition to the famous violin concertos in A minor and E major, as well as the double concerto in D minor, Johann Sebastian Bach composed further violin concertos and at least one oboe concerto. Some of the missing concertos were preserved in the form of harpsichord concertos as arranged by Bach himself. For this reason not only enthusiastic Bach virtuosos, but lately also Bach researchers (Siegele 1957, Fischer 1971 and Breig 1976) have gone into the question of whether and to what extent it is possible approximately to recover the lost originals by means of reconstruction.
Musicological investigations concentrated in particular on the autograph (written by Bach himself) scores of the harpsichord versions, since these reflect the process of rearrangement in many details (violin effects in the harpsichord descant, corrective processes, insertions, melody turns, basic changes or octave transpositions taking into account the restricted tonal range of the harpsichord, unusual part leading, among other things). Evaluation of such characteristics was considerably eased by the fact that also the violin concertos in A minor and E major and the 4th Brandenburg concerto (actually also a violin concerto) have come down to us as autograph arrangements for harpsichord providing important clues to Bach’s working techniques. The method of critical examination of the sources is also the basis of reconstructions of the Violin Concertos in D minor (according to the Harpsichord Concerto in D minor, BWV 1052) and in G minor (according to the Harpsichord Concerto in F minor, BWV 1056), as well as the Concerto for Oboe d'amore (according to the Harpsichord Concerto in A major, BWV 1055).