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In Reply to: RE: Cluelessness, Part Deux posted by Tony Lauck on January 26, 2015 at 18:10:45
the value of upsampling and downsampling to determine whether or not a higher resolution format has merit over Redbook. If memory serves, you find Redbook severely lacking with your recording.
Why not do as this test did and simply record a single event in multiple native resolutions?
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If it's a live event then it would involve running multiple converters in parallel. If it's a master tape transfer, then one could play the tape twice, and presumably there wouldn't be any tape wear involved. But if someone else did this, you have no idea what they did. There is a lot of secret sauce involved in mastering, no matter what people may claim to do or not do.
My comments were directed to people who want to KNOW what the differences are with regards to format conversions. The only way to know this is to do the format conversions oneself starting with the same recording and then playback with the identical playback chain. This has the further advantage that by experimenting with different formats and different filter parameters one can train oneself to hear all of the various artifacts involved. This training will make the various "tests" that others come up with relatively easy. I spent the better part of 100 hours doing these experiments some years ago. In the end, I concluded that it was all a waste of time. The lower resolution formats were lower resolution no matter what I did.
The 44.1 kHz format could not transparently reproduce the output of my cassette player.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
it will answer all your questions and eliminate the need for speculation.
Thanks. This answered my questions. I note that they used live acoustic music with decent venues, so it is not surprising that they got positive results, even though listeners had not been specifically trained to discriminate sample rates. However, they did not fully comply with the ITU recommendation for blind tests. [ITU-R BS.1116-1, ITU-R BS.1534-1, ITU-R BS.775-2] Had they used specifically trained listeners or used a preliminary stage to select the best scoring listeners they would likely have gotten much greater statistical significance.
The paper didn't give a specific model number for the RME ADC that was used, so I could not investigate further as to the specific ADC chips used. In all likelihood, they used a multi-bit sigma delta modulator that sampled at around 5 Mhz. The converters therefore downsampled to whatever PCM formats were chosen. As far as I know, all modern audio ADCs that output PCM downsample internally. The differences between downsampling in hardware and software will be small and will depend on details of the DSP involved. There is nothing lost in principle in following a two step process downsampling over a one step process except loss of 1 bit of resolution from the original output format. Given that the RME outputs 24 bits, this would mean restricting the precision to 23 bits, which if reduced to 44/16 would be irrelevant. In the case of reducing to 44/24 it might possibly be relevant, however the 88/24 format already has more resolution in the range 0-20 kHz because of the higher sampling rate.
One might have made the 44 kHz playbacks sound better by using different filtering in playback. Apparently, the experimenters just used the filters provided by the RME Fireface DAC.
IMO this was a good paper, great in comparison to horrible examples such as Meyer - Moran. It could have been better. One thing that I did not like is the use of second tier converters. Better results could have been achieved by taking the converters out of the picture and using file level conversions. This would allow extensive experimentation on how the different possible filter designs affect sound. It would also ensure that all of the analog equipment operated identically in all cases and the only differences being the DSP processing. Furthermore, when doing DSP processing file to file it is possible to capture that impulse response of the filters very precisely, providing much better documentation of the experimental procedure.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
All in all, I found it used a far more plausible setup than any number of contrived ones you find (like the M&M).
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