Doubling bass lines
In a lot of 17th- and 18th-century music, the instrumentation of the basso continuo group is not specified by the composer; The part is often just called 'basso'. This gives musicians a significant influence on the sound colour and character of the music but it also raises a lot of questions among musicians in the field of historically informed performance practise. Moreover, the variety of string bass instruments and their names in the 17th and early 18th century were far from standardized, which means that even if an instrument name is added, we can not be sure about the size, register, tuning or amount of strings.
8 foot pitch and 16 foot pitch
The register is something that violone players, double bassists and organ players have to make decisions about, since this is often not indicated in the music. The usual bass clef register is called the 8 foot pitch register. This is the written pitch and the register in which violoncellos, bassoons and harpsichords play. An octave lower is the 16 foot pitch register, in which double basses and contrabassoons play. It is nevertheless written in the same clef, which means that the players transpose to sound an octave lower than written. The violone is mainly an 8 foot pitch instrument but also has quite a few notes in the 16 foot pitch register, so a player can also decide to play some notes or passages an octave lower.
The concerto grosso
The instrumental repertoire from the early 18th century consists for a great part of of concertos for one or two soloists with string accompaniment. A variation on the solo concerto called the concerto grosso made became very popular. One or two soloists were joined by a bass instruments such as violoncello or bassoon, and a continuo instrument. They formed a small ensemble that we now call the concertino. The accompanying group, called the ripieno and now sometimes the concerto grosso, had more players per part and consisted usually of strings and one or more continuo instruments.1 In this way, composers created more possibilities to have big contrasts in the music. Famous examples of concerti grossi are the 12 Concerti Grossi Op. 6 by Arcangelo Corelli and the 6 Concerti Grossi Op. 3 by Georg Friedrich Händel. Concerning the role of the double bass in this style, there is a general consensus that historically informed performance practise asks for leaving out some notes and passages, if nothing is indicated by the composer. Usually, the double bass is supposed to play just the tutti passages and not during the solos,which are both often marked in the parts.2