Marantz CD15 CD Player Double Differential D/A Conversion

Double Differential D/A Conversion

This electronic mouthful could just as well be Double Dutch to most readers but it's a technology increasingly being used in CD player design. The idea is to split the signal up in the digital domain where such manipulation is essentially free from loss. These split signals are designed to operate two digital-to-analogue converters in parallel, a technique where the resolution of the pair is greater than that of an individual unit. The most effective way of adding the audio outputs is in 'push-pull' or balanced mode where the even harmonics are cancelled and DC levels are restored.


The Philips DAC7 integrated circuit is such a balanced design where the differencing push-pull summation of the plus and minus signal which it outputs is termed differential. A further improvement in theoretical performance is possible if you repeat the trick, in this case with two complete DAC7s. There is an added advantage in that each DAC now handles a single channel, helping to improve channel separation. Higher resolution and lowered noise and distortion are the objectives of this complex signal processing.