G-C-F-Bb tuning?

[tannis_root]

Hello,
I'm thinking of working with a local acoustic stringed instrument maker (guitars, wood-topped banjos, mandolins) to make a no frills unamplified "bass" type practice instrument. Lower pitched than the low E on an acoustic guitar, but maybe not as low as a the low E on an acoustic bass. Scale length could be anywhere from 25" to about 29" and I don't care what note the lowest note is pitched to so long as it's right for the gauge and scale being used. Any thoughts or suggestions?

One easy way would be to use a baritone guitar scale length of approx. 27" and simply use the lowest 4 strings of a baritone guitar set for a BEAD tuning. That low B is like a .070 gauge. But I wonder if that low B is "low" enough?

A low G note would be more bassy - about halfway between a baritone guitar and an acoustic bass. Hmmm...that would be a GCFBb tuning.

 

[tannis_root]

I thought of a possible solution - single course Bajo Quinto strings and scale length! The Bajo Quinto has a 25.5" scale length - same as or similar to the scale used for an acoustic guitar or openback banjo. So the scale length would be 25.5" since that's a pretty common one. And the Bajo Quinto is tuned in all 4ths - ADGCF. The low A string in a bajo quinto set is an "A1" octave and the gauge is .078. That D string is a "D2" octave .062. The G string is "G2" .047, and the C string is "C3" .036. And there are string sets as well as individual GHS strings. (Just leave off the "F" string...making it a bajo cuatro I suppose! So the strings are already mapped out and easy to obtain. An ADGC tuning would be like EADG minus the low E.