The bazantar is a custom made string instrument invented by musician Mark Deutsch, who worked on the design between 1993 and 1997 (US patent 5883318 issued March 16, 1999).
The bazantar is a five string double bass with 29 sympathetic and 4 drone strings and has a melodic range of five octaves. It is designed as a separate housing for sympathetic strings (to deal with the increased string tension) mountable on a double bass or cello, modified to hold drone strings.
Here is a 10 min video by Mark Deutsch himself.
