The wooden dowels under the straps of the treble drum — its coarse tuning control.
Cylindrical wooden blocks wedged between shell and baddhi on the dayan. Driving a gatta downward increases strap tension and raises pitch; easing it up lowers it. They are the coarse control — hammer taps on the gajra do the fine work afterward.
Gattas are moved in opposite pairs to keep tension even around the head. The bayan traditionally has none; its lower, flexible pitch is set by lacing alone. Players check gatta positions on unfamiliar instruments first — badly seated blocks make a drum fight every tuning attempt.
Further reading
Rebecca Stewart, The Tabla in Perspective (PhD dissertation, University of California, Los Angeles, 1974).
