The modern instrumental format for the son, consisting of guitar, tres (in rural ensembles) or piano (in urban ensembles), marímbula (in rural ensembles) or double bass (in urban ensembles), bongos, trumpet and two singers who play claves and maracas. It is an outgrowth of the sexteto ensembles, which began adding a trumpet to the standard lineup around 1930 to increase overall volume in outdoor venues.