Why 24bit/48kHz/96kHz/
Reply #417 – 2007-04-08 05:10:27
First post for me on here, and I guess reading the 17-page + argument is quite enlightening. There are obviously a lot a widely varied opinions on these topics, and although perhaps not backed by instrumentation and a lab environment, would like to report some of my own findings, which have taken a slow poke like myself years to really understand. Let me state right upfront that I have been involved in recording, production, mixing and DJ activities for over a quarter of a century. Somehow this means experience, but also probably hearing damage, LOL! The scope of my comment should be relating to one thing in particular: size of listening environment. Here is the analogy: If I look at this site's graphic logo in its intended resolution for example , it looks perfectly fine, smooth and sharp. However, if I suddenly take the same logo and blow it up to fit a 2.5 meter-wide billboard poster (approx. 10 ft) then its edges will look ugly, jagged and just plain wrong.... My experiences have afforded me the opportunity to work on a weekly basis with very large-scale sound systems, the range going from 5,000 to 60,000 Watts of amplification, in rooms that can sometimes accommodate as much as 10,000 people. The one thing which has become immediately apparent to me is that the bigger the room's volume and its sound system, the more easily I was able to distinguish artifacts which were totally inaudible in a smaller space. I also have access to studio-grade gear in vast quantity, and must confess that it is really hard for me to pick out the kinks between an MP3 file and its 16-bit 44.1 kHz source when listening on a pair of big Tannoy monitors and Bryston mono blocks in a studio, it seems that the sound fails to develop enough to really make a difference. Forget about headphones. But surely I have done a number of tests on very large-scale listening systems, and that is where it has quickly become apparent that all of the extra information contained in a properly-encoded 24-bit / 96 kHz file does help make a noticeable difference in how it sounds compared to a 16-bit / 44.1 sibling. Also experimented with up-sampling existing CD's via open-reel recording, simultaneously re-recording the result into a workstation at 24/96 to amazing results on quick A/B tests, which no doubt can be attributed to tape compression and other usual artifacts. But there is no question in my mind that many of the arguments presented in the thread need to be illustrated within certain parameters, and that in my mind room size happens to be one of the most important ones. The rough description of the type of tests I am basing my experiences on would be as below, in a room that holds about 1,500 people, roughly 30 meters wide by 25 meters deep with a ceiling height of 5 meters, with adequate amplification to bring sound to about 105 dB (?) without audible distortion, would imagine in the neigborhood of 15,000 Watts with plenty to spare, barely hitting '3' on the master volume: -1) CD Red-Book Audio version of song DAC from Pioneer CDJ-1000 Mk 2 player. -2) vinyl version of same. (obviously, depending on cartridge, tonearm calibration, etc.. used on test was standard DJ-grade Ortofon cart + Technics SL-1200 turntable) -3) File up-sampled via 15 ips tape recording to 24/96 from workstation. AD from Metric Halo 2882 - DAC from RME Multiface. -4) recording of vinyl at 24/96. AD from Metric Halo 2882 - DAC from RME Multiface I can hear that the tape transfer has more bottom and smoother highs in pretty much any size room. Never mind that part, it's the 'tape-effect' for sure. The big story for me was is how fond of COHERENCE my ears were. When it comes to pure ear-pleasing power (punchiness, coherence and smooth presentation) the vinyl usually won as long as mastering wasn't horrible, even though there were many high frequency bits just missing in the very high upper register, and many percussive details in the midrange also a bit smeared. The Red-Book audio CD sounded edgy and generally grating, screechy hi-hats, jagged brass and typical lack of bass, including what I'd call no 'woof' (percussive bass factor?), but certainly had a fair amount of extra detail and pleasant overall imaging/separation compared to vinyl. The vinyl transfer to 24/96 PCM audio was certainly subjectively much nicer sounding than its CD counterpart, but obviously subject to the same limitations as its vinyl source. The up-sampled tape to 24/96 seemed to have the best of all worlds: the cleanliness of its original CD source, along with the 'glue' that passing things through tape seem to bring, overall effortlessly smooth sound, and the kind of dynamic range that really made listening to the music a joy. I realize that I should have included 16-bit / 44.1 kHz versions of the tape up-sample and vinyl transfers to really make this more of a valid test, but this is all I did. Not having access to DSD recording gear, this was obviously not included in the test. (let me not fail to thank Sony for its continued lack of support for the very formats it invents) Quite empirical, for sure, but at least it left me convinced that there is a place for all of those extra bits, and that somehow judicious analog re-mastering can improve just about any sterile-sounding 16-bit digital source. The last bit I really noticed is that when passing the pure digital source through a tube line amp, (didn't have the luxury to try a stand-alone tube D/A where I did this) it predictably smoothed things a bit more, and made the Red-Book CD at least listenable. The up-sampled 24/96 via tape sounded absolutely glorious through tubes on playback. My little moral of the story also seems to be that anything that 'reconstitutes' the signal on playback, even if totally adding distortion and other artifacts appears to be the real important factor to pleasing the human ear in large-scale listening situations. The bigger the space, the more you notice it. For most people's everyday home listening situations, all of this stuff would probably make no difference whatsoever. There you go, I hope some of you can see beyond my probable failure to follow some of the site's TOS for the bit of interesting data it may hold for those who care about its applications in similar large acoustic spaces. I would of course welcome hearing any comments on this... D.