The electrical driving‐point admittance of a linear transducer is linearly dependent on a sufficiently small impedance loading its mechanical port (a sufficiently small load impedance is one that is much smaller than the transducer's mechanical driving‐point impedance). This makes possible a method for measuring the mechanical impedance presented by a smooth surface to a sliding indenter. The indenter acts as the mechanical port of a transducer whose electrical admittance causes the output voltage of a linear active network to equal the surface impedance in amplitude and phase. Calibration of the system does not depend on a detailed knowledge of the transducer's dynamics, but does require that the transducer be operated at frequencies for which its mechanical impedance is much larger than the surface impedance. This method has been used to measure groove impedances of phonograph records.