I just completed a 5 string mandocaster for Will Fly. The original Fenders which inspired it were Strat style instruments with 4 single strings, and were made between 1956 and 1976. A 5 string version was made in Korea between 2000 and 2002.
I made mine with a mandolin scale length of 355mm. The obvious tuning is in fifths, C G D A E (or rather: c g d’ a” e”), a mandolin with an extra low C. Or a mandola with an extra top E. But this instrument has single strings so perhaps it should really be thought of as a short scale tenor guitar with an extra top E – a “mandotenor” which is what Will has christened it. Whatever you call it this tuning works out pretty well for an electric instrument. However you’re not going to see many acoustic instruments tuned like this. It’s no accident that instruments tuned in 5ths – violin and mandolin family instruments – tend to have four strings or courses (string pairs). Instruments like guitars with 6 strings/courses are more likely to be tuned in 4ths. More strings and you not only find trouble with breaking top strings or rattling bottom strings but also you’re asking the sound box to operate over a wider frequency range. 7 string guitars are almost always solid electrics. I’ve played a five string fiddle, a very nice instrument from a very good maker. I did my grades on viola and very much enjoy the sound of that low C string but to me this instrument felt compromised at both ends of the register, lacking both “bite” on the top E string compared with a violin and “growl” on the bottom C compared with a viola. But perhaps I should add that my ability as a bowed instrument player is pretty modest, perhaps a good player could make more of it.
Of course 5 strings or courses offer other possibilities. Cittern players often use C G C G C or D G D G D. For more key versatility there are tunings like C G D A D as used – an octave lower – on the baritone cittern I made for Doc Rossi.
And of course it could always be tuned like Keef’s 5 string Tele, G D G B D. Play them old mandocaster blues!
Here’s the mandocaster / mandotenor in action, played by Will: