A digitalized two channel audio recording adapter which can be used in conjuction with the home type video tape recorder has been trially manufactured. This report describes the overall system design and the outline of its recording circuits. An adaptive delta modulator having a digital code detector and selector was used for a simple analog to digital conversion. The sampling rate of the modulator was selected as 1.1025 Mbits/s, considering the requirement to record the digitalized data on the home use VTR. Theoretically estimated signal to noise ratio was about 70 dB for low frequency input signal. The recording bit rate of 2.8665 Mbits/s was selected to record two channel serial data on the VTR.