I saw an example of a bass with sympathetic strings seated under the fingerboard, but now I can't remember where or who the artist was that created and played it. I'd like to know more about it and about the music that was made on it. Please let me know if you have any information!! Thanks.
You are looking for Mark Deutsch's bass. He developed the multi-stringed unit to fit under the fingerboard and through the bridge. He calls it a Bazantar
