Unfortunately, TWA will not work with instruments with f-holes rather than a traditional acoustic guitar soundhole. The limitation is the size of the X-Brace mounted internally. This brace measures 3x3x1.25" and will not fit through an f-hole. I suppose one could temporarily affix their TWA using blue painters tape or an alternative mounting method, but we've not seen it done.
Josh Rosenbaum
Has anyone tried the ToneWood with other acoustic string instruments, e.g., upright bass, cello, violin?