I've been asked to explore exotic lower end bass instruments and wanted to hear if anyone has a suggestion that produces an original tone for me to explore. For instance, the subcontrabass saxophone, the serpant, the octabass, are great examples. Any others? The instruments should be playable (for example, an instrument that only exists in a museum and no one can play it won't work).
Any other interesting, exotic, low instruments that produce an intense and interesting sound that is also playable?