Classical Bass #10 incorporates a ‘triple reflex’ design in which the back is divided at the waist into two reflex panels, braced and tuned to fundamental frequencies which couple reflexively with the top fundamental mode through the enclosed air volume. The result is a spread of the lower range peaks into a ‘resonance plateau’ which provides a strong response to low-mid frequency string excitation and so a rich low range, valuable for a bass instrument.
At higher frequencies the back panels can be excited by complex modes of vibration of the internal air volume, but generally less than the string-driven top. But this bass certainly poses challenges for music-acoustic research and has implications for double bass design as well.
It has been sent to a leading guitar ensemble for playing trials on which I shall report hopefully soon.