The string length is 79/162cm, and a body depth of 16.2cm the original instrument is in 3 pieces in the Brussels Museum, the bridge has an unusual dolphin shaped bridge ending which may have replaced the original bridge in 1698 according to the museum. The original rose shown below needed some restoration before a new one was made. The original instrument currently exists in 3 pieces in the museum as seen below.
Theorbe de Pieces in d' (a=415Hz) (The Lesser French Theorbo) based on Vendelio Venere, Padua c1611 (Vienna KHM C47)
This small Theorbo has a comfortable flat back yet just a wide as other theorboes is also referred to as a Theorbe de Pieces in d' or Lesser French Theorbo, or even a 'Luth a Double Manche (according to B.Narvey). String length 75.7/121cm, or 75.7/160 with a longer Italian theorbo neck as may have been on the original. This instrument has extra holes and nut groves for being strung in single 7x7 or 6x8, or 6x double and 8 single basses (as on the original)
This instrument may have started off life as a Bass lute, the neck on this instrument is narrow for a theorbo so may be the original Bass lute neck. The extended neck is more likely to be a conversion by a French lute maker like DesMoulins hence it's strung as a Theorbe de Pieces. However some early short necked, large bodied 'small' theorboes survive that are said to be original short necks, possibly tuned at standard chitarrone tuning in a' but at Paduan/Venetian Pitch (466Hz or 456Hz, according to E.Segerman 2008) possible at that higher pitch due to the shorter string length of 75.7cm but still justifying a double re-entrant stringing. It's a shallow theorbo at 15.5cm deep as seen below:
Student Theorbo based on Sellas (Paris E.547)
This student Theorbo is the most popular the string length is 85.7cm with 168.7cm bass courses with 17 ribs to make the instrument cheaper. The folding version is also shown below. Here the famous Canarios for solo Chitarrone buy Kapsberger played here by Richard MacKenzie, and here playing Biagio Marini in Oxford.