J.S. Bach’s Invention 9 BWV 780 arranged electric guitar & bass guitar duo in its original key of F minor. A challenging invention to play particularly from the note reading point of view. The #sheetmusic video plays back at 58 bpm and the music is presented in both staff notation & TAB. The arrangement is based on the original piano score. There are many accidentals to read and it is easy to make music reading errors. A legato playing approach is required in the playing in what is a slow tempo and melancholy movement. In the sheet music score the ornaments are indicated but do not sound. The ornamentation in place is placed at the important cadence points in the movement. In the keyboard video score, which guitar players may wish to refer to on the PlentyMusic YouTube channel ornaments have been written out as they sound in the realisation to represent exactly what is being played. The full score is presented in staff notation and the parts with the option of staff notation and TAB. Bass guitar players may well want to experiment with the octave choices in the higher sounding sections bars 5-7 and elsewhere in the movement. Accompaniments are in place allowing guitarists to participate in ensemble activities as part of practice routines. The electric guitar sounds on one side of the stereo channel and the bass guitar on the other. The accompaniment tracks play back at 52, 54, 56, 58, 60, 62 & 64 quarter note (crotchet) beats per minute. There is a two bar count in /click track at the beginning of the accompaniment tracks. Playing the music of Bach is challenging and his style is demanding and uncompromising in the consistency required to perform it accurately. As a composer Bach is not so much an innovator but one of those who brings all the musical elements of his time together and takes them to an altogether much higher artistic and technical level. The Bach Inventions are generally considered to be intermediate level movements when played on a keyboard instrument. The principle behind J. S. Bach’s two part inventions is to take a musical idea or motive and then process it following the rules of good contrapuntal writing using the compositional processes of the baroque and at the same time referencing the closely related keys in the key system. Inversion, repetition, sequence, transposition, rhythmic augmentation & diminution amongst processes are evident in Bach’s inventions as most other music of the baroque period. J. S. Bach composed 15 Inventions in a collection dating from 1723 intended to introduce keyboard players to composition techniques of the baroque. They are excellent ensemble movements.