Abstract A miniature automated spherical acoustic resonator (50 mm dia) assembly has been developed to measure sonic speeds in liquids and stock tank oils (petroleum). The resonator is being used to determine sonic speeds and equilibrium phase boundaries. Comparison of experimental sonic speeds in liquid n-heptane with earlier measurements by different methods (J.W. Boelhower (1967) and M.J.P. Muringer, et al., (1985)) show good agreement. Results on the sonic speed and the location of wax drop out in two stock tank oils (filtered and unfiltered) are also presented.