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Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
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Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
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In Reply to: RE: All FIR filters are fatally flawed. posted by jmlpartners on February 11, 2009 at 20:38:10:
"Hey Tony, in case you forgot, the goal of the digital signal in question was to recreate two cycles of a 20KHz sine wave. Apparently, all your high-powered digital filters can’t do the job."
It is not possible to represent 2 cycles of a 20 kHz signal in the 44.1 kHz format. Regardless of the DAC, you can't do it. If you don't like it, then blame Sony / Philips. This issue would be very clear if you were to try two cycles of a 200 Hz signal in the 44.1 format. All of the DACs would look pretty good.
"It comes the closest to the truth..."
You are expressing a preference in a multi-dimensional space. Neither DAC provides a very good approximation to your idealized waveform, and you have given no basis other than your eyes for choosing between the two alternatives. Others will look (and listen) and reach a different conclusion. In addition, with a different waveform the preferences might be different.
"Regardless, what ever the number there will always be a discontinuity at the beginning and the end of the sample stream"
That is true, but it has something to do with the nature of digital audio and not the implementation of a playback filter, whether done in the digital, analog or biological domains. The Sampling Theorem applies only to band limited signals. There are no non-zero band limited signals of finite duration. So according to your criteria, no digital audio system can perfectly reproduce your waveform. I am not going to accuse you of being a troll, but if you really believe that digital audio is inherently no good, then you have no business being in this forum.
Your two cycle test signal exists only in the platonic world of numbers. It does not exist in physical reality. There is no way to create sound waves that start and stop instantaneously and no way to transform those sound waves into electrical signals that start and stop instantaneously. If you do not believe this, then my advice would be to take a course in Physics.
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: All FIR filters are fatally flawed. - Tony Lauck 08:59:09 02/12/09 (0)
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