The next pictures are from a Puerto-Rican Cuatro as 4-double strings instrument, with the previous tuning that makes it a guitar-lele.
We may utilize a E4 guitar string for the A4 of the A3:A4. We may utilize a D3 guitar string for the A3 of the A3:A4. We may utilize a A2 or better for lower tension a D3 guitar string for the E3 of the E3:E4. We may utilize a B3 guitar string for the E4 of the E3:E4. We may utilize a G3 guitar string for the C4 of the C3:C4. We may utilize a A2 guitar string for the C3 of the C3:C4. We may utilize a D3 guitar string for the G3 of the G3:G2. We may utilize a E2 guitar string for the G2 of the G3:G2. With the above choice of strings, and given that the scale length of this shorter guitar (baritone ukulele and the quatro with 48-52 cm scale length) is about at the A4 note of the e4 string of a normal guitar, the strings are either exactly at the intended tension given the scale length or one note above or below the normal tension!
Some advantages of this kind of tuning where in all the pairs the two strings are one octave apart are the next
1) it covers larger range of octaves than the tuning of an ordinary (tenor) ukulele!
2) It also gives the opportunity with sufficient skill in the right hand fingernails, to play only the higher strings of each pair or only the lower strings of each pair moving therefore in two different octaves the same melody or harp-ism.
3) Furthermore when singing, the instrument supports the voice in two octaves rather than one octave which makes singing more well supported by the instrument thus easier and more comfortable and accurate!
While a tenor ukulele is about the range of a human mezzo soprano, and a charango-ukulele, about the range of a soprano human voice, the above tuning for a baritone ukulele or a Quatro it is about the range Contralto human voice.
