@Doggy79:
for what it's worth, 30" scale 5- and 6- string basses, while rare, do exist; TB member @khutch tunes his Squier VI in fifths starting from C1; even more to the point, another TBer,
@AV8R, has converted his Ibanez SRC6 to BEADGC tuning. Read all about it (including needed drillages):
Ibanez SRC6 Successful Conversion
IMO the main problem is finding suitable strings: in the same thread I mentioned the DR short(actually medium, ~34"-long winding before taper)-scale .125" available at Bass Strings Online. If you're interested, grab one or four of them before BSO closes shop, which is about to happen unfortunately:
Here's a post
Alternatives by Warwick:
Ibanez SRC6 Successful Conversion
Here's a post
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Full (5-string) set options by Warwick and other brands (DR, Dunlop, I may have missed others) here - page-search for "medium scale" and take note when they're 5-string sets - where you also can find single strings for the high D:
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Invalid Link Removed by @Aidil with minimum and maximum string lengh requirements for the SRC6. It looks like this set by Pyramid should also fit, if only by a hair:
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(Could other short scale options also work? Yes, if their full winding is ≥32.5" long. That's definitely a yes for DR as said, a yes for GHS, a no for Dunlop and most others, a "no idea" for Warwick. Unfortunately short-scale strings fatter than .11" are hard to come by anyway.)
Finally, you could have either
Pyramid or
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