Thumb Position - On Double Bass

On Double Bass

For the double bass, thumb position is used when playing above high G (on the third ledger line in bass clef notation for the double bass). To play passages in this register, the player shifts his hand out from behind the neck and flattens it out, using the side of the thumb to press down the string. When playing in thumb position, the use of the fourth finger is replaced by the third finger, as the fourth finger becomes too short to produce a reliable tone. Bass instruction books often teach thumb position by having the player place the left-hand thumb on the high G note (on the third leger line in bass clef notation), so that the 1st, 2nd, and 3rd finger can then play the Ab, A, and Bb. Once in this position, other notes can be accessed with slight modifications; the B or C (above the G) can be played by making a larger space between the thumb and the first finger; a player with a large hand may even be able to play a high D with their thumb still holding down the G, if they stretch their hand fully open.

In this same position, notes below the G can also be played. By barring the thumb across the G and D strings, the G and D notes can be played in quick succession. Alternatively, notes on the D string can be performed in quick alternation with notes on the G string. While traditional methods rarely discuss playing on the A or E string in thumb position, French pedagogue Francois Rabbath (and his disciples such as Paul Ellison) advocate the performance of notes on the A and E strings. While introductory manuals start teaching thumb position by stopping the G string on the high G, any of the notes on the upper part of the fingerboard can be stopped and held by the thumb.

One issue with the use of thumb position is that it is harder to produce vibrato with the thumb than with the fingers, because fingers have much fleshier pads than the side of the thumb. While the difference between the vibrato sound produced by the fingers and the thumb may not be noticeable in a passage of moving notes, if there is a held note which is stopped by the thumb, which is vibrated, the difference may be noticeable. As such, some players use finger substitution to replace the thumb with one of the fingers.