This work focuses on a eddy current system based on a new inversion principle requiring the processing of low frequency measurements of the matrix of self and mutual impedances among coils of an array of coils. Numerical simulations presented in another work have proven that this algorithm is suitable for fast inversion of ECT data. This work is focused on a first experimental prototype tailored for the particular inversion algorithm. Specifically, we show that measurements of the impedance matrix can distinguish between volumetric defects of different lengths and we discuss the main issues to be solved in view of the inversion of the experimental data.