Ronroco fret calculator
The ronroco is the big brother of the charango, and Aquila's string chart lists two sizes: the Argentine ronroco, or charangón, at 42 cm, tuned a fourth below the charango, and the Bolivian ronroco at 50 cm, tuned an octave below. The calculator opens at 420 mm with 18 frets: the 1st fret sits 23.57 mm from the nut, the 5th 105.36 mm, the 7th 139.68 mm and the 12th 210.00 mm.
Ronroco fret positions, 420 mm scale
Distance of each fret from the nut, from the previous fret and to the saddle on an Argentine ronroco.
| Fret | From nut (mm) | From previous (mm) | To saddle (mm) |
|---|---|---|---|
| 1 | 23.57 | 23.57 | 396.43 |
| 2 | 45.82 | 22.25 | 374.18 |
| 3 | 66.82 | 21.00 | 353.18 |
| 4 | 86.65 | 19.82 | 333.35 |
| 5 | 105.36 | 18.71 | 314.64 |
| 6 | 123.02 | 17.66 | 296.98 |
| 7 | 139.68 | 16.67 | 280.32 |
| 8 | 155.42 | 15.73 | 264.58 |
| 9 | 170.27 | 14.85 | 249.73 |
| 10 | 184.28 | 14.02 | 235.72 |
| 11 | 197.51 | 13.23 | 222.49 |
| 12 | 210.00 | 12.49 | 210.00 |
| 13 | 221.79 | 11.79 | 198.21 |
| 14 | 232.91 | 11.12 | 187.09 |
| 15 | 243.41 | 10.50 | 176.59 |
| 16 | 253.32 | 9.91 | 166.68 |
| 17 | 262.68 | 9.35 | 157.32 |
| 18 | 271.51 | 8.83 | 148.49 |
How to use it
- Tap Ronroco 420 mm for an Argentine ronroco, or type 500 mm for a Bolivian one.
- The fret count starts at 18 as a placeholder, since no reliable source gives a standard count: change it to the number on your neck.
- Keep the Ukulele compensation, the closest match for nylon strings on a short scale.
- Print at 100%, measure the 100 mm bar and tape the sheets on the splice line.
Help and explanations
For a Bolivian ronroco, type 500 mm: the 1st fret moves to 28.06 mm and the 12th to 250.00 mm. Then print the template at full size on Letter or A4. Everything runs in your browser, free, with no sign-up.
Two instruments called ronroco
Aquila separates them clearly. The charangón or Argentine ronroco measures 40 to 42 cm and is tuned a fourth below the charango, D4 G4 B3/B4 E4 B4 from the 5th course. The Bolivian ronroco runs 45 to 50 cm and is tuned an octave below the charango, G3 C4 E3/E4 A3 E4. Wikipedia gives 44 to 50 cm overall.
That's a difference of 80 mm in scale, so presets matter less than your tape measure: double the distance from the nut to the 12th fret and type that in.
Ronroco vs charango
Both have five double courses of nylon strings and the same re-entrant layout, with an octave pair in the middle course. A 370 mm charango puts its 12th fret at 185.00 mm; an Argentine ronroco at 210.00 mm and a Bolivian one at 250.00 mm. The deeper sound is the one Gustavo Santaolalla made famous on his album Ronroco and on film soundtracks.
The calculator suggests 1 to 2 mm of saddle compensation, labeled as an estimate. Finish by checking the octave of each string with the intonation checker.
Tips
- Mark every slot from the nut, never fret to fret, so ruler errors don't add up.
- Check the printed 100 mm bar before you cut: a printer that rescales by 2 % moves the 12th fret by 4 to 5 mm.
- Tune a fourth or an octave below the charango with the ronroco tuner.
Frequently asked questions
What is the scale length of a ronroco?
About 40 to 42 cm for the Argentine ronroco (charangón) and 45 to 50 cm for the Bolivian ronroco, according to Aquila's string chart. Measure yours from the nut to the 12th fret and double it.
Where is the 12th fret on a ronroco?
At half the scale: 210.00 mm on a 420 mm Argentine ronroco and 250.00 mm on a 500 mm Bolivian ronroco. The 5th fret is at 105.36 mm and 125.42 mm respectively.
What's the difference between a ronroco and a charango?
The ronroco is larger and lower: an Argentine ronroco is tuned a fourth below the charango on about 42 cm, a Bolivian ronroco an octave below on up to 50 cm, against about 37 cm for the charango.
How is a ronroco tuned?
Argentine ronroco: D4 G4 B3/B4 E4 B4 from the 5th course to the 1st. Bolivian ronroco: G3 C4 E3/E4 A3 E4, an octave below the charango.