Studying the Denon DCD-810

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Hi,

I’m actually studying the structure of the dcd-810 looking at some improvements I could do, and I’m facing some interrogations.

The DCD-810 is basically constituted of an SM5807 low pass filter (4 fold oversampling filter). The serial stream is directed to 2 PCM56H (one for each channel) DACs. On the output of each DAC, there’s a sample&hold circuit.

The S&H is constituted of a demuxer which loads a styroflex capacitor (470pF) with the current output of the DAC. The demuxer is driven by the deglitch signal of the SM5807.

As far as this is a dual DAC architecture, I can’t figure out why this S&H circuit is needed. On an mono-DAC (both L and R samples are alternatively proceeded by the DAC) I can understand the need of S&H when a sample of the other channel is proceeded.

The PCM56 datasheet is clear about this :
The obvious solution to the phase shift problem in a two- channel system would be to use two D/A converters (one per channel) and time the outputs to change simultaneously. […] It should be noted that no deglitching circuitry is required on the DAC output to meet specified THD performance. This means that when one PCM56 is used per channel, the need for all the sample/hold and controls circuitry associated with a single DAC (two-channel) design is effectively eliminated.

So why Denon kept the S&H circuitery even if not needed ?

Many thanks in advance.
 
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