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speakers for 24/96 audio

is it correct to assume that 24/96 audio would be indistinguishable from cd quality when listened to with speakers with a 20khz 3db and rapid hi frequency roll-off?

Or more precisely, that the only benefit comes from the shift from 16 to 24 bit, not the increased sample rate, as they higher freq content is filtered out anyhow?

related to this, which advice would you have for sub $5k speakerset with good higher freq capabilities for 24/96 audio?

thanks!
mizuno
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almarg
9,670 posts
 
Shadorne, I am in essential agreement with your last post. As I said earlier:
An infinitely long series of samples is required for the mathematics to work out perfectly. The consequences of that will be most significant for spectral components that are transient and that approach the Nyquist frequency (i.e., half the sample rate).

The extent to which that may be audibly significant on most recordings is probably conjectural. The Wilson Audio cd I referenced, among many others, leads me to believe that in general it is not a major factor as a practical matter.
I particularly second your statement that:
... the graphical representation of waveforms and the "digital staircase" form one of the biggest and most enduring audiophile myths that analog is inherently better than digital.
BTW, the following excerpts from the technical notes accompanying the Wilson Audio cd I referenced (which I indicated provides the best reproduction of solo piano in my experience) may be of general interest:
The recorded perspective of the piano in this recording is close, as though the 9' Hamburg Steinway in being played for you in your living room. Of course the actual recording was not made in a living room! Instead, the great room of Lucasfilm's Skywalker Ranch, with its incredibly low noise floor and fully adjustable acoustics, was used.... A pair of Sennheiser MKH-20 omni microphones were employed ... amplified by two superb pure class-A microphone preamps custom-built for Wilson Audio by John Curl. MIT cable carried the balanced line level signal to Wilson Audio's Ultramaster 30 ips analog recorder. Subsequent digital master tapes were made through the Pygmy A/D converter on a Panasonic SV-3700.
Best regards,
-- Al
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shadorne
7,477 posts
 
Al,

Glad to hear we can all agree. Sony and Philips engineers did a great job with redbook CD, it would indeed be hard to go against all their research.

I agree that transients close to the Nyquist are going to be the most challenging to reproduce faithfully, however, there is really not much in th eway of sounds that one can call music above 15 KHz anyway.
irvrobinson
295 posts
 
"Kijanki, are you implying that 24 bit data words have a "finer grain" than 16 bit data words? That each bit represents a smaller incremental signal level? "

"That's the basic reason to us more bits in each sample in digital signal processing of any kind, isn't it?"

That isn't my understanding of how it works, Mapman. Each bit of word length corresponds to 6.02db of dynamic range, or, technically, s/n ratio. So, with 16 bit words you get about 96db of dynamic range, and with 24 bit words 144db. And, of course, 65,535 voltage levels with 16 bits, and 16,777,216 with 24bit words. So 24 bit is "finer grain"?

Yes and no. Yes, there are 16M levels, but there's so much more voltage range to cover. If you reference the maximum level to, say, the 2v max line level used in consumer audio, and that's 24 1s in a row, then all zeros will be 144db below 2v, which would take cryogenic circuits or whatever to achieve. That means you're wasting the bits below the resolution of modern amplification systems, which is probably something like 100db below 2v of power amplifier output, including all amplification stages (I'm being very generous), which means you're wasting 44db of dynamic range, or about 7 bits of word length. So that means you're probably using about 17 out of 24 bits in a real system. And, of course, I'm probably generous by several db of s/n ratio in a real system, so 16 bits isn't far off of what is the resolution limit in a home system, and "finer grain", meaning a better s/n ratio, won't be audible by most mortals.

What 24 bit words are good for is eliminating digital clipping in the recording studio. There's no such thing as a 144db peak in music. :-)

So unless I'm completely misguided (always possible) 24 bit audio isn't really "finer grain" in the 96db of dynamic range that 16 bit audio can encode. 24 bit just goes higher or lower, or a bit of both.
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almarg
9,670 posts
 
Irv, keep in mind that it is generally accepted that signal can be perceived at levels that are significantly below the level of random broadband noise that may accompany the signal. 15db or more below, iirc. So amplifier noise floor is not really a "floor" below which everything is insignificant.

Also, quantization noise is significantly correlated with the signal, at low signal levels, and is therefore perceived as distortion rather than noise. Dithering will minimize that effect, but it has its limitations and my understanding is that it is often not properly applied.

That said, I think we are all in agreement that the main usefulness of 24 bits is in the creation of the recording.

Regards,
-- Al
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shadorne
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That said, I think we are all in agreement that the main usefulness of 24 bits is in the creation of the recording.

Agreed.

However, I would add that high resolution recordings are targeted at audiophiles - so this new high resolution media is useful in that you tend to get a better quality recording that has NOT been heavily compressed for mass consumption. So they ARE useful to audiophiles but not so much from the "improved resolution" but mostly because audio that gets formatted this way tends to be a better quality master rather than a master intended for restaurant, pub, iPod & car FM radio play.
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