Please explain sigma-delta modulator in my signal path

[Jim_Austin]

I understand why this 2xDSD file is being down-converted: The Devialet Expert Pro is specified as handling only DSD64. But what’s with the sigma-delta modulator?

Thanks,
Jim

[ged_hickman1]

What’s under the sigma box? Any DSP? Or volume control on the devialet? If so this may apply

Native DSD processing

Unlike with PCM, processing 1-bit DSD signals in their original form is not practical because 1-bit signals do not have enough dynamic range to perform common operations like volume adjustment, eq, mixing, or convolution directly on the 1-bit representation. So when DSD IS processed, the input to the processing chain is a 1-bit DSD signal, but the output must have more dynamic range. In Roon’s case, we perform processing with 64-bits of precision, so whenever you process DSD, you end up with so…

[Jim_Austin]

Here’s the image without the Sigma-Delta box. Yes, there’s a volume control in the Devialet, but it should be able to accept DSD64 input. That conversion appears to be happening before the Devialet, if I’m thinking about it right.

[brian (Brian Luczkiewicz)]

The output of the sample rate conversion is multi-bit audio, but at the sampling rate of the DSD that is to be generated–in this case 2.8224MHz.

The sigma delta modulator transforms that multi-bit stream back to a 1-bit DSD stream that the Devialet can understand.

[Jim_Austin]

Got it–thanks Brian.