The launeddas are a simple reed instrument, constituted by three canes of different size, two of which are linked to form the croba and a third one called mancosedda which is free.
The croba is constituted by a “drone” called tumbu and from the mancosa. Tumbu and mancosa are tied up together in proximity to the mouthpiece and in correspondence with the inferior knot of the mancosa.
While the superior binding (crobadura de asuba) holds tightly the two united canes, the inferior binding (crobadura de asutta) includes a small 1-2 cm segment of cane that serves as a spacer so that an angle of 10-15 degrees is created between tumbu and mancosa. The binding is obtained with 4-5 curls of pitchy string to assure stability for a long time.
This is the instrument part that serves as “drone” and is tuned on the tonic note of the instrument. It is not provided with digitable holes, and can therefore produce only one note. If the instrument is tuned to FA, the tumbu produces a FA.
Its length varies from about 52 cm, which emits the acute RE note, to around 100 cms which gives the low RE. The distance of a semitone corresponds to a dimensional difference of about 4 cm. To better keep and transport the instrument, the tumbu is divided in two segments: the one not tied up to the mancosa is called anzetta. The two parts are provided with a joint that can be easily found thanks to a reinforcing binding on the anzetta.
Usually some decorations can be seen around the junction with the anzetta. They are there not only for decorative reasons but also as a reference point to correctly place the anzetta.
The mancosa owes its name to the fact that is grasped with the left hand (manca means left in Sardinian). It is provided with five holes (crais), but only four of them are digitable; the fifth hole (arrefinu) is the most distant from the reed, and plays autonomously when the other holes are covered by the fingers.
The holes are rectangular and are about 2x5 mm big. This form allows small modifications on the instrument, for instance in case of decreasing notes, the cut can be prolonged in the direction of the reed.
It is similar to the mancosa but, it has nearly always smaller dimensions and a smaller section (mancosedda = small mancosa). Because of these characteristics, it generally produces a more acute sound.
The segment of cane from which the reed (linguazzu) is cut is called cabitzina. This part is also separately prepared, one for every reed: tumbu, mancosa and mancosedda. On the mancosa and on the mancosedda the cabitzina is directly inserted because the section is almost equal and therefore a spontaneous joint is created. On the other hand, to be able to insert it in the tumbu, another cane segment (about 1 cm long) is necessary to reduce the inside section.
The instrument mouthpiece is modelled with virgin wax that fills the space between the cabitzinas of the croba and covers the extremity of the canes, to avoid the direct contact of the lips with the sharp surface of the cane and also to prevent the air from passing between the lips and the canes, since this would cause a diminution of the pressure of the air inside the mouth.
On the free surface of the reed a small wax quantity is placed to allow the tuning of the instrument. The wax quantity placed on the reed of the tumbu is much bigger than the one on the mancosa and mancosedda. Actually, it is necessary to make the reed heavier in order to obtain a two octave lower note in respect with the tonic note produced by the melodic canes.