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| According to some... CD sound quality is inadequate. |
In the comments to a previous post, Fabio Zolli asked:
I would like to ask your opinion about high resolution audio files like 96/24 or 192/24 (I know it's off topic but I didn't know where to post). I think there isn't a really audible improvement among standard 44/16, taking into account also your mp3 test. Thanks for your attention.
Thanks for the note Fabio.
The MP3 test shows that even if we do hear a difference, at the level of quality tested (~320kbps MP3), without comparing the "studio master" sound, it's virtually impossible to know which is better/more accurate. Amazing given just how much data is being thrown out by MP3 encoding!
Personally, up to now I have not been able to ABX a difference between properly dithered 16/44 and the 24/96 source. Others have also done some fantastic testing around this like Mitchco at Computer Audiophile with different test methodologies.
It has been 30 years since the introduction of the CD (PCM 16/44) standard for mass consumption. The fact that we have not seen good controlled tests to show that 16/44 is somehow "lacking" (when listening to music at normal volumes) compared to 24/96+ or SACD tells me that 16/44 is most likely good for any circumstance. Much debate for example was sparked in 2007 by Meyer & Moran when they published their report based on work with the Boston Audio Society when listeners could not detect a significant difference between hi-res (DVD-A and SACD) analogue output versus the output from a 16/44 A/D/A loop.
Knowing the above, reading stuff like this should make an unsuspecting audiophile wonder why the inferiority of 16/44 wasn't proven ages ago! The author writes: "For me its clear that 24/96, 24/192 and DSD are superior to 16/44.1 in many meaningful ways..." Really?
The only rational issue I have come across "against" the 44kHz sampling rate is that with older DACs, the Nyquist frequency at 22kHz is too close to the potentially audible 20kHz upper range and the steep "brickwall" filter may cause audible effects. But this issue was addressed with upsampling and slower roll-off filters long ago (I know... yet another contentious issue for some).
Admittedly, I will seek out 24/96 audio for favored albums and rip my SACDs as 24/88. My rationale's simple... Since storage is cheap these days, I consider doing this as reasonable "insurance" to guarantee that everything that science tells us is humanly audible is captured in the digital sampling with plenty of headroom above 20kHz. I believe this is a reasonable price to pay in terms of storage even if I do not ultimately get an audible benefit because my ears aren't good enough for the task (like one pays for insurance never knowing if it's actually needed). Furthermore, objectively, all my DACs seem to be optimal at these 2x sampling rates as well showing nice frequency extension and excellent dynamic range measurements.
As for 24/192... Christopher "Monty" Montgomery at xiph.org has written an excellent review of this topic including examples of how this could be detrimental to sound quality (like intermodulation distortion which also can be shown with 24/96). Likewise, Dan Lavry has written about the technical issues of 24/192 in his whitepapers like this one.
Personally, I have yet to find music I thought could benefit from this high sampling rate (how many microphones can even accurately record >40kHz?). Even though storage is cheap, I'm not convinced that there's anything to be gained going from 96kHz to 192kHz theoretically or otherwise. The cost-benefit ratio is hard to justify when benefit seems to be zero! (BTW I have come across some albums like Carmina Celtica from Canty off the Linn download site at 24/192 with unusually high noise level above 45kHz which I suspect could create some very nasty intermodulation distortion if not properly filtered.)
Bottom line:
I'm happy with 16/44 if the music is well recorded and mastered. For my favorite tunes, I'll go for 24/88 or 24/96 if available to "ensure" that I'm not missing something. To date, I have happily downsampled many 24/192 albums to 24/96 (or 24/176 to 24/88) without any reason to think that I'm somehow "missing out" (rather than gaining space for more music!). As for DSD, I only have a few albums verified to be sourced from an original DSD recording.
As many others have commented before, the main "enemy" to good sound these days is not about the audio format - yes, even the much-maligned-by-audiophiles MP3 can sound excellent if the underlying content is good. Rather, the way the album was recorded and mastered is more important. For example, the loudness war has caused more damage to sound quality than we can ever gain going from 16/44 to any high-resolution format. I believe sound quality "evangelists" like Neil Young would do well to "wage heavy peace" on that silly "war" and in the process stay relevant.
Feel free to leave me a note especially if there are good reasons to consider keeping 24/192 music on my server system! :-)
One more thing... There is one situation where you'd definitely want to either upsample or run a higher sampling rate - if you're using a NOS DAC. However, this is more to do with reducing aliasing distortion in the audible spectrum.
Musical selection tonight: Going to have a listen to k.d. lang's Ingénue (1992) again... It's been awhile!
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