本帖最后由 鱼花 于 2021-9-10 11:06 编辑
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- Some other dacs like some of the teac and ifi dacs have a 'pseudo-NOS' option made possible by the architecture of the burr-brown chip it seems. Though it's not actually NOS all the way through. The top 6 bits are though.
- Others like the ADI-2 and more recent AKM dacs have a 'super slow' filter which is basically a zero-order-hold OS filter. Still OS, but produces a result very similar to actual NOS.
复制代码"NOS" in these cases means it bypasses the 8x digital filter, and just leaves the zero-order-hold OS in place. Same for TI and AKM.
DAC chips just don't have enough DSP power to run proper 256x or higher digital filters, so they typically have digital filter up to 352.8/384k rate and rest is just OS by copying same sample N times.
However, TI chips pass DSD inputs straight to analog FIR conversion stage and now AKM chips have similar feature feeding DSD data straight to their SCF conversion stage. So DSD inputs can be true NOS. This allows running proper 256x or higher digital filters and high quality modulators not constrained by the on-chip DSP.
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RME has DSD Direct mode for playing DSD. And for PCM it has digital filter disable option. And if you input 352.8 - 768k PCM it's digital filters are bypassed anyway. With PCM input it is however always oversampling (at least with S/H aka ZOH).
Holo being more similar to the DAC8 DSD as having two separate DACs for PCM and DSD. But with the difference that also PCM side is discrete R2R and both PCM and DSD side can be run NOS without digital filters.
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