Mastering Captured Vinyl For CD
Reply #97 – 2009-01-17 01:53:01
24-bits: "ludicrously over specified". Thanks for the link. I did listen to the AES UK recording, and recall that he said that 96kHz/24-bit was ludicrously overspecified, and repeated both the sampling rate and bit depth a minute of two later. That ties in to the 52 kHz sampling rate he later mentioned (implying no more the 26 kHz should be audible to humans at even the loudest level, even though it's unlike anything in music). If that's true, there's 44 kHz of excess sampling frequency (22kHz excess bandwidth) at 96kHz, which is pretty ludicrous. 24-bit is also OTT, though it's often sensible in computers to use an integer number of bytes per sample per channel. Shannon space seems to encapsulate the 'gamut' of human audition, analogous to the gamut of colour space for human vision.He mentioned some room noise data from Louis Fielder that's relevant to this discussion. I hadn't picked up the name, so that's handy if I want to look it up. It sounded like that was from among the quietest listening rooms possible, though the graph he referred to doesn't show up too well on the mp3! It could well be true but be irrelevant to "real-world" listening rooms with peak level set to about as loud as a human can bear, or ultra-quiet rooms with more modest listening levels. In either of those circumstances, it seems that 16-bit is good enough for the delivery format (though digital reconstruction filters in DACs or digital speakers might as well be implemented in higher resolution to keep any further dither to lower levels. I thought the beginning was a useful introduction for those not too familiar with speaker design, where he discussed the improvements possible by using active speakers with a separate amplifier dedicated to each driver and the improvements in sensitivity, frequency response, bass extension, loudness, thermal management and protection that could provide compared to traditional passive designs where one has to forego sensitivity, attempt to match all driver impedances and provide power-capable components in the passive crossover.