This paper reports on the implementation of a multi-channel electronic stethoscope designed to isolate the heart sound from the interfering sounds of the lungs and blood vessels. The multi-channel stethoscope comprises four piezo contact microphones arranged in rectangular and linear arrays. Beamforming and channel equalisation techniques are applied to the multi-channel recordings made in the aortic, pulmonary, tricuspid, and mitral valve areas. The proposed channel equaliser cancels out the distorting effect of the chest and rib cage on the heart sound frequency spectrum. It is shown that the applied beamforming methods effectively suppress the interfering lung noise and improve the signal to interference and noise ratio by 16 dB. The results confirm the superior performance of the implemented multi-channel stethoscope compared with commercially available single-channel electronic stethoscopes.