On this page you will find theorbos (also called chitarrone), archlutes (arciliuto) and liuto attiorbatos. All of which have always interchangeably been called by any one of these terms -and especially 'theorbo'- by the uninitiated. This is also a field of nomenclature further confused by regional varieties. Historically, all of these instruments were born out of wanting lower bass notes but being limited by string making technology of the time. The only solution was to make the bass strings longer.
I make necks and long extensions with carbon fiber reinforcement hidden under veneers and a small upper pegbox to reduce weight where it matters the most.
Typically a large lute with an extension that carries long bass strings typically twice as long as the fingerboard strings, characterized by re-entrant tuning where the two first strings or courses are an octave lower than in renaissance lute tuning: gdafcGF EDCB'A'G'F'. Can be tuned with first string in g or a. Smaller versions exist: The French theorbo or théorbe des pièces is tuned in d, while the tiny tiorbino is tuned in g' or a', so a whole octave higher than the normal size. Larger theorbos are mostly for continuo playing while the smaller ones are for solo repertoire.
All theorbos can be built with single or double fingerboard strings and in any case I make enough pegs for 7+7 or 6+8 stringing. Both ways are historically accurate, I would recommend single strings. An extra 15th bass string tuned in F# slightly spaced apart from the 14th can also be added.
Renaissance tuning with a long extension and single bass courses. The archlute differs from the theorbo in that it does not have re-entrant tuning, so you can play from all renaissance lute tablature. The repertoire for this type of lute greatly benefits from having nine or ten frets on the neck.
String lengths around ~59cm & 93cm, 1+6x2 + 7x2. An instrument similar to the German swan neck baroque lute in having a short extension and diapasons with octave strings. The tuning of this instrument is the same as a renaissance lute, but with the added bass courses.