There's an article about them somewhere here that I put together some time ago. However, they use lower-resolution loops with oversampling and filtering to create a lower-speed, higher-resolution result. THey are sort of a special case in that they depend upon oversampling to provide the bandwidth needed to implement noise shaping. When discussing bandwidth and slew/settling in most designs the engineering principle is to use just enough bandwidth, not too much, and not too little, to preserve signal fidelity.ĭelta-sigma designs use noise shaping to push the noise above the audio (audible band). Greater sampling rate means greater noise bandwidth as well, more stringent requirements on DAC and support circuitry settling and stability, etc. You must somehow create new samples between the existing samples so, while the algorithms can be pretty sophisticated, it is still a guess. Running the DAC faster may or may not help in the end. I'm not sure if/why a computer would do it better than a dedicated DAC.Īnd I'm not sure about your questions regarding DSD, except to hazard that perhaps the higher rates push audible noise out of / higher above the audible frequency range. Others will definitely be able to explain this in more depth, but that is what I understand to be the gist of the theoretical argument in favour of higher sample rate PCM. Get the sample rate high enough, and use an appropriate filter, and the ringing stays completely out of the audible spectrum. a 96Khz sample rate, this pushes the ringing up to the 40Khz range (exactly where depends on the filter type used). By using a higher sample rate, the nyquist frequency, and therefore the transition range, and therefore the ringing, is pushed up to near the new (higher) nyquist frequency. At 44.1Khz PCM, this ringing may be in the audible band (beginning around 20Khz or lower). This filter introduces ringing (pre- and/ or post- echo, depending on the filter).
With PCM digital, there is a low-pass filter placed just before the nyquist frequency (e.g. I'm definitely not an expert on this but have just been asking similar questions in another thread and doing some reading and getting some answers from more knowledgeable forum members that may help with your question too. EDIT: I've left this post here so the thread still makes sense, but I now understand that what I said here is essentially incorrect
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