Hitachi VT-F381A Owner's Manual page 20

Getting Started (Initial Setup)
dynamic range of over 90dB will record either stereo or monaural
broadcasts with the highest quality possible. Linear sound, on the other
hand, will record monaural sound using the same format as a non hi-fi
VCR. Stereo programs are recorded in hi-fi on both the left and right
channels and also recorded on the linear track as monaural.
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