Printheads for jetting a print fluid. In one embodiment, a printhead includes a main body configured to attach to a stack of plates, where the stack of plates forms a row of jetting channels configured to jet droplets of a print fluid. The main body includes a supply manifold configured to provide a fluid path for the print fluid to the row of jetting channels. The supply manifold comprises a primary manifold duct and a secondary manifold duct that extend in parallel in alignment with the row of jetting channels. The primary manifold duct is fluidly isolated from the secondary manifold duct at end sections of the primary manifold duct, and is fluidly coupled to the secondary manifold duct toward a midsection of a length of the primary manifold duct. The secondary manifold duct is fluidly coupled to the row of jetting channels.