Three-wave turbulent interactions and the role of eddy size on the turbulent electromotive force are studied in a spherical liquid-sodium dynamo experiment. A symmetric, equatorial baffle reduces the amplitude of the largest-scale turbulent eddies, which is inferred from the magnetic fluctuations spectrum (measured by a 2D array of surface probes). Differential rotation in the mean flow is times more effective in generating mean toroidal magnetic fields from the applied poloidal field (via the effect) when the largest-scale eddies are eliminated, thus demonstrating that the global turbulent resistivity <?format ?>(the effect from the largest-scale eddies) is reduced by a similar amount.