5. Can you shed some light on the relationship/ differences between the following 4 allied instruments: rudraveena (been), surbahar, kachhuva & sitar?

Can you shed some light on the relationship/ differences between the following 4 allied instruments: rudraveena (been), surbahar, kachhuva & sitar?

Kachhuva is known as kachhuva sitar and not kachhuva been (rudraveena). From historical record, it appears that kachhuva sitar is somewhere in between the instruments surbahar and normal sitar. The name comes from kachhuva or a tortoise, as the lower part of the tumba is akin to the upper surface of a tortoise. To my mind, there is no other similarity, though the name kachhuva sitar has continued over the centuries. I have heard kachhuva sitar only once in my life. I was too young to discern the differences of sound and plucking technique of a kachhuva sitar as compared to a surbahar. It is evident therefore that, the instrument seems to have disappeared, as it had no worthwhile and unique characteristic, which could add in any substantial manner to the existing Indian instruments like surbahar and sitar.