Foundation instruments
Historical term for instruments that realized the bass part harmonically in the age of figured bass, such as organ, harpsichord, or theorbo.
What it means
Fundamentinstrumente (foundation instruments) is a historical term for instruments that realized the bass part harmonically in the age of figured bass. They include keyboard instruments such as organ and harpsichord and plucked instruments such as lute, theorbo, and harp, which could play complete chords to a bass.
Musical use
In the Baroque the basso continuo ensemble formed the foundation of the music: a foundation instrument played the chords according to the figures while a bass melody instrument, such as cello, viol, or bassoon, held the bass line. The term was used especially in the 17th century, for instance by Michael Praetorius, and sets these instruments against the melody instruments.
Foundation instruments should be distinguished from pure melody instruments such as violin or flute, which can play only one line, and from the fundamental bass, which is a theoretical model of chord roots. The foundation instruments, by contrast, are the actually playing instruments of the continuo.
Performance practice
If you play continuo, listen to the solo parts and support them rather than covering them. Choose chord positions and volume so that the harmony stays clear, and ornament carefully in the style of the period.