Generated pulses, having random amplitudes relative to particle sizes which lie in an especially wide range, are fed into a plurality of parallel channels, at the input of each of which there is an amplifier. Each amplifier has a different amplification factor and saturates in response to a correspondingly related maximum input pulse magnitude, so as to define a subrange of acceptable pulses. Saturation of a particular amplifier disables its channel and enables the adjacent, lower amplification, higher channel to accept or be saturated by the same pulse. Each pulse, when accepted by a channel, is further processed for particle analysis purposes. During the processing, the pulse amplitude is reduced by the same amplification factor as that of the accepting channel, so as to return all pulses to their initial relative amplitudes.