Abstract: A biological amplifier system is disclosed for displaying the cardiac conduction system activity, particularly the His bundle activity on a beat-to-beat basis by a non-invasive technique. Plural sets of bipolar leads are connected by electrodes to the body surface so as to obtain the same biological signal on each set. The leads are connected in parallel to plural low noise amplifiers which provide simultaneous but separate amplification of the same signal. The amplified signals are added together in a summing circuit with the effect of noise reduction by averaging the random noise components. Noise reduction is further enhanced by use of negative feedback to a reference electrode and by use of a low pass filter and notch filter.