New experimental microwave dielectric relaxation, electrical conductance and ultrasonic relaxation kinetic data are reported for solutions of sodium tetraphenylborate (NaB phi(4)) dissolved in 1,2-dimethoxyethane (1,2-DME) and tetrahydrofuran (THF). 1,2-DME is a bidentate ether solvent, whereas THF is monodentate. NaB phi(4) is strongly associated to ion pairs, and these ion pairs are dimerized to a considerable extent in both ether solvents.