The CD-1's maximum output level was 2.08V from the unbalanced jacks, 4.15V from the balanced. Output impedance measured a moderate 330 ohms (balanced) and 165 ohms (unbalanced). DC levels were unmeasurable, and the CD-1 doesn't invert absolute polarity.
Fig.1 is the CD-1's frequency response and de-emphasis error. The 0.8dB rolloff at 20kHz is greater than what we measure in most CD players and digital processors, and may be on the threshold of audibility as a slight reduction in top-octave air. The lower pair of traces in fig.1 shows a positive de-…