The Drums
Surdos
The pulsing sounds of the Surdos also called Marcação (time markers) are responsible to keep the band on tempo. These drums are the heartbeat of most samba based bands. Each Surdo named 1&2 is played in alternated beats and has a very low tuning close to E1 and D2 if you are using a piano scale.
Dobra
Played with to mallet, we can say that Dobras are the melody of a samba-reggae band. Its mid-range sound is used in between the surdos with rolls and off-beat patterns that creates the samba reggae rhythm. The Dobra is normally tuned by ear but its pitch should be higher than the Surdos 1&2.
Repique
The clave keeper and the calling drum are good ways to describe the Repique. Played with two flexible plastic sticks the repique are responsible for the samba clave and the calling of changes in the arrangement. This is instrument has a very high pitch tuning which sound cuts through the entire band.
Snare
This is instrument is used in a different way in samba based bands. Its white noise pitch provides the connection between Repiques, Dobras and Surdos rhythm and often matches the Repique clave pattern.