In Reply to: RE: PS Audio DirectStream DAC - an extremely interesting video. posted by rick_m on February 14, 2015 at 08:16:40:
No way. It has to have an analog "reconstruction filter" to block all the aliasing energy above Fs/2 or they will likely wreak havoc with your amplifiers and speakers. And maybe even ears... It's really within the filter that the original signal is "recreated".
Most of the NOS DACs have a zero order hold, at least to the extent that there are no logic glitches in the output signal. This greatly reduces the amplitude of the high frequency images. It also provides a high frequency roll-off below Fs/2, thereby diminishing high frequency response, a potentially useful "tone control" effect for systems that are otherwise too bright. One can debate whether the ZOH is an analog filter or a digital filter, but a filter it most certainly is.
Without this ZOH filter one gets a stream of Dirac impulses and if these are not filtered there may be serious high frequency energy to disrupt sensitive drivers such as tweeters.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
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Follow Ups
- RE: PS Audio DirectStream DAC - an extremely interesting video. - Tony Lauck 02/16/1511:16:09 02/16/15 (0)