Axiom Home Page Forums General Discussion Stereo 24/96 downloads;Sampling rates&devices for dummies

Was reading through a site I found in my bookmarks and came across some Apple news I missed: Apparently they're talking about allowing some 24/96 file downloads. Audiophiles everywhere are thrilled.

And that got me to realizing that I don't really understand the differences in the sampling rates as they apply to real world listening. So I was hoping some of the smart people here might be able to explain it in lay terms.

Obviously I know that 24 bit is better than 16 bit and 96 > 44.1 and all that... what I don't know is what releases already have that higher rate... how many have it natively rather than being upsampled... and how someone like me might find it either for download or for ripping.

I recall being excited by the Apple Lossless encoding, being able to compare to FLAC and WAV from my CDs (Regular old CDs are Redbook, right? Meaning my entire collection is 16/44.1?) But now I've come to find out that apparently there's plenty of music out there that's better? Have I been wasting money?

Or... is most still sold in only 16/44.1, meaning I haven't really missed much, other than a few select recordings of artists I probably wouldn't have bought anyway?

As I understand it, 24/96 is DVD audio, and SACD is somewhere in between. Is that correct?

In terms of real world application, is 24/96 really noticeably different in a 2ch setup? Or is it primarily for multiple channel recordings? I've only ever listened to music in stereo and haven't really been convinced that surround audio is better. (And if it is, wouldn't that mean that for those purposes we'd want better rears?)

I guess the quickest way to answer me might be simply to recommend a piece of media that is a nice 24/96 recording and let me hear it for myself. I typically rip my CDs into Apple Lossless and play them from an AppleTV, letting my own DAC handle things for the main room (and its own to output analog to the multi-room amp) but I have a BRD player that I could use for comparisons... though I'd give Apple a shot to see if it could rip it into 24/96 too.

(Or do I already own a good one? I bought both the CD and the BRD of the Dave/Tim Live at Radio City. I have the BRD here still unopened)

From there, the question will become whether the AppleTV plays 24/96 (apparently older Apple devices will play the file, but not necessarily at that rate), then whether I'm able to tell a difference, and then finally if I should upgrade. I was thinking about possibly ditching the AppleTV for an Auraliti or something else that would more easily interface with my Crestron controls. (As it is now I end up listening to my music streamed from iTunes half the time because I don't feel like turning on the TV or another iPhone app to control the local files on the ATV. If the AppleTV turns out to be adequate, though, there is software I can buy that opens up an API to those apps.)

Bah. I type too much. I'm about 60% sure I understand this stuff, but I want to be positive.

When an analog signal is turned to digital is has to be quantified in some way. That's where the bitdepth and sample rate come into play. The quantification process takes the amplitude of the incoming analog signal and assigns it a value. With 16-bit samples the value is between 0 and 65535, with 24-bit it's 0 and 16,777,215. The sample rate is how many times a second the analog signal is checked from 44.1kHz is obviously 44100 times a second.

The higher bitdepth gives finer steps between each possible quantization level. The higher sampling rate packs the quantized levels closer together. They both allow for a more accurate tracing of the original analog waveform.

More is probably better, especially during mixing and mastering. But for distribution and playback in an average listening environment the extra information is easily lost to the surrounding noise. There's a 50% increase in storage space needed to go from 16 to 24 bit. And a slighly over 100% increase going from 44.1 to 96 kHz. But Internet connections are fast, and hard disks are big, so it matters less these days.

Oh, and the layout of a CD is specified by the Red book standard, but the audio is stored in PCM (pulse code modulation) format. Just about every form of digital audio has its roots in PCM. SACD was unique in this respect in that it used a form of PWM (pulse width modulation)*.



*Which some people say at the rate used, combined with the reconstruction filters actually resulted in less high frequency resolution than even 44.1/16 CDs. But more resolution in the mid frequencies and lower.

I'll point out that this is merely a rumor, and one with a tentative connection to Apple at best. Yeah, it looks good to slap Apple on a headline (see Foxconn coverage--what, they make stuff for HP and Dell too?!), but there's no confirmation whatsoever that Apple's doing this.

Dave, in real world applications for home audio, rates higher than the 16/44.1 of CD haven't proved to be "obviously"(or at all)better. The care taken in the original recording process and the mixing and mastering applied to it will determine audible quality, not sampling rates or bit depth greater than the CD standard.

As long as they don't force me to pay for it the folks that swear it adds something can have at it IMO.

(of course I'd sooner go back to the stone ages then pay Apple corp a penny of my money for anything but thats another discussion)

I still prefer to have the pressed CD in hand but if I must download, then I prefer/want at least CD quality downloads, which is very difficult to find. I have seen more sites offering these higher bitrated music forms than plain ol' cd quality stuff, I guess it is to be able to charge more for it to make it worth their while to offer it.

I pulled a few 24/96 recordings down from the internet. I'm not sure if the appleTV is converting them or not. Can't really tell any difference through these speakers.

But my Axioms arrive tomorrow

Hi DaveB,

As JohnK and Club Neon pointed out, the technical benefits of 24/96 recordings are simply not audible compared to the standard Red Book CD of 16-bit/44.1 recordings. If you do immediate comparisons of the same material from the same digital masters, and you don't know which you're listening to, there is no audible difference that I, or most of my "golden-eared" colleagues can reliably detect. Of course, many of the technically naive tweaks at some of the high-end magazines believe otherwise, but they don't approve of blind comparisons or science in general.

In casual comparisons, if you believe you'll hear a difference, you will, such is the power of psychological bias.

I encourage you to try more multi-channel music playback of stereo material using DPLII, DTS Neo6, or Logic7, using the music modes and careful setup. With some excellent recordings, the expansion of realism is profound. Of course, there are also some discrete multi-channel SACD and DVD-A discs that are wonderfully realistic. That's because great care was taken in the recordings, not because of any supposed audio benefits of much higher sampling, etc.

Regards,
Alan

The 16-bit 44.1 kHz coding system of the redbook CD standard was very carefully chosen because it covers the range and sensitivities of human hearing.

If you take a 24/96 recording and down-sample it (as accurately as possible) to 16/44, I doubt anyone in a blind test will be able to hear the difference. In fact, most people, even on very good equipment, can't tell the difference between 24/96 lossless and 256 kbps lossy MP3. It's just hard for audiophiles to admit it.

That said, I do collect 24/96 recordings. I do it because in most cases the higher resolution/rate implies that the artist and recording engineers have put extra effort into making sure the mastering has been done right and with high quality.

A high quality master means everything.