Axiom Home Page Forums General Discussion Stereo A difference in Vinyl & CD - Seeking explanations?

Given that (I assume) redbook CD is capable of achieving this Nyquist rate, is SACD/DVD-A complete overkill?

That's controversial. There may be some benefit in higher sample rates, but how scientifically justifiable it is, I don't know. You can't go by allegations that a high-resolution SACD or DVD-A higher sample rates "sound better", as usually other concurrent changes exist, such as re-mix and digital cleanup from original master tapes, etc. SACD and DVD-A often sound better, but whether this is solely (or even primarily) due to the higher sample rate seems debatable.

For example DVD-A discs usually have a Digital Dolby or DTS 5.1 compatibility track so they'll play on existing DVD players without requiring a specialized DVD-A player. The DD 5.1 max aggregate sample rate for all 6 channels is 448k/sec. Even if you discard the LFE track and assume the total bandwidth is available for the remaining 5 channels, that's only 89k/sec. By comparison SACD sample rate is an incredible 2.8 million/sec. Yet to my ear, the DD 5.1 track on my DVD-A discs (89k samples/sec/channel) sounds equally good as my SACD discs (2.8 million samples/sec).

They're both generally better than regular CDs, but how much is due to the higher sample rate is unclear. That DD 5.1 sounds so good seems to indicate going much higher that 89k/sec is overkill.

For simplicity I omitted that SACD DSD is 1-bit samples vs CD or DD 5.1 using 16 to 24-bit words.

In addition to the theoretical higher sample rate advantages, most current SACD and DVD-A players have disadvantages vs CDs and DD/DTS 5.1: they require 6-channel analog connections to your amp, so your amp's fancy digitally-implemented bass crossover, calibration, EQ, etc is useless. Eventually this will get fixed, but it's possible the very real analog-related disadvantages of most current SACD/DVD-A players may swamp the theoretical advantage of higher sample rate.

Peter, as I said in an earlier reply, my view is similar to Joe's on this point. As set forth by the motion picture music editor's views I linked there, little if any of the improved sound is due to more bits or higher sampling rates, but rather to multi-channel surround, better remixing, better remastering, etc.