Mark Wybierala wrote: There is no reason why a 25" scale archtop wouldn't work as long as you could find a way to employ a piezo pickup effectively.
You can even go with magnetic pickups if ou use thick shortscale strings like the GHS Brite Flats. These can be tuned down easily by three semitones which compensates for the difference in string length. Or ou try to get hands on one of the rare 5 string sets for shortscale basses and use the B-D strings as E-G on a guitar scale. Tensionwise that should roughly give the load of long scale strings. An (old, to be restored) archtop should be ideal for such instruments since suitable hardware is easily available as well.
BTW: one of my guitars is currently tuned in fifths. I am using Daddario Chromes with a maximum thickness of 0.08" tuned to the low F, just one semitone above the bass. On a 62.8 cm scale, ie, Gibson alike. Not nice but playable.
But that is not the scope of my project. I want to design an unconventional bass playing acustically better than my small SX (silent, but nice sound), but also electrically functional and build that from scratch. For the contest, for the fun of it and in order to learn a lot.
Today i learned about Tom Ribbecke's Diana bass and found that encouraging to try my idea. Very unconventional bracing - a bass bar combined with X bracing.