In digital audio systems, the ΔΣ modulator has been widely used as a digital-to-analog convertor (DAC) for Class-D amplifiers. The ΔΣ modulator is generally evaluated in the frequency domain [1]. In this paper, we propose a novel system to evaluate the ΔΣ modulator in the time domain by observing its transient response. In our system, we use a field-programmable gate array in order to reduce cost. Our system enables the ΔΣ modulator to evaluate its transient response in the time domain in real time.