CD algorithm mistake?

[hunterchristy]

So, perhaps this is the wrong forum in which to post this, but none of the others seems any more applicable.

I just watched Dave Grohl's new "Sound City" doc. In it, there's a section titled "The Eighties," and they go into the first wave of the digital revolution. Cut to Neil Young, feeling duped by the advent of compact disc, who states something to the effect of "The problem is that when they created the algorithm that converts music into the digital realm, there was a mistake in it"

Then they move on.

WHAT?! What mistake? Is he counting 16 bit 44.1 as a mistake? Am I missing something?

[Marc Alan Goodman]

Sounds like typical Neil Young giberish.

You could literally call anything a mistake. You could call the fact they did it a mistake. Maybe the first CDs pressed had an issue with the conversion? Or maybe he's saying that they chose poor sample and bit rates? Or maybe he's talking about the error correction algorithms that make up for all those scratches on your CDs and secretly make them sound like totally muddy crap? Who the hell knows.

[chris harris]

Isn't Neil still hemorrhaging money trying to turn his Lincoln Continental into an electric vehicle?!?!

[The Scum]

Sony Pcm1630's were the cornerstone of the CD business for about a decade. There really wasn't anything else if you wanted to record PCM audio in the 80's. Their conversion was shown to be somewhat less than a full, robust 16 bits. Steve St Croix wrote a number of articles for Mix about it in 94/95.

Early DAT machines had similar problems - 14bits of data and 2 of garbage.

Is that Neil's beef?

[fossiltooth]

Well, some of the the very earliest converters didn't have the greatest anti-aliasing filters, but that was fixed pretty early on from what I understand. That was actually an analog front-end problem and had nothing to do with "algorithms."

Back when that was an issue, it could alter your high frequency response a little by either rolling off a little too much top or giving you a slight HF resonance peak. Clocking also improved dramatically over the decades, but fidelity within the audible spectrum had surpassed tape far before it got where it is today.

I've also heard rumors that early on, some MEs didn't know how to master properly for CD early on and even printed the RIAA EQ curves used to cut lacquers onto their CD masters (We're talking about a 6dB-per-octave below 1kHz, which is like playing your album through a tin can and string.)

That sounds too mo-tarted to be true, but people swear it happened. If it did occur, I doubt those CDs would have ever made it to release, but it may have led people inside the project to think there was something wrong with the medium, rather than simple user error. If anyone does have a record of that happening, I'd love to track it down! I've heard that anecdote a bunch of times, but never a source for it.

As much as Neil Young can talk a little gibberish with this stuff, I'd give him the benefit of the doubt and assume he meant one of those things, rather than the "algorithm," which was just never one of the early complaints to my knowledge. I think that was just a fancy buzz word that stuck in his brain at some point.

And Scum, I'd believe that about the early PCM1630 being more like 14 bit. To be fair, I bet that none of us own any recordings -- even classical ones -- that use a full 14 bits of dynamic range. But I suppose that the lost bits could make good dither more essential than it is with 16 bit. Quantization noise tends to be about 90dB down in 16 bit which makes dither maybe-just-barely-necessary on long fades or on super-dynamic material. I guess it would have to be about 78 dB down in 14 bit. (For a sense of scale, it would be super-rare to find even classical recordings that approach even near 60dB of dynamic range.)

Anyway, I don't think they did much of an edit in the technical/fact-check department for the movie. (in the brief interview scene with Rupert Neve, basic engineering terms like "microphone amplifier," "module" and "crosstalk" are singled out as being crazy-advanced techno-babble.) But the film doesn't suffer much for it. It's a compelling story that's more about people than about things, which is great, I think.

There are a bunch of offhand comments that don't make any sense. Like one of the Heartbreakers talking about the new-fangled 1980s console next door that had "only one fader"... Immediately after we see a shot of the new-fangled console at the studio next door... And it has a lot more faders than the one at Sound City!!

But I happily let stuff like that slide. In this case, I figure that's just Neil being Neil. I think people know what to expect by now when it comes to him and accurately keeping up with technology. It's not his strong suit. And it doesn't have to be. Motherf*r made Harvest. All sins = forgiven.

[GooberNumber9]

To be fair, I bet that none of us own any recordings -- even classical ones -- that use a full 14 bits of dynamic range.

Telarc's 80's release of Bolero maybe?
This one:
http://www.amazon.com/Ravel-Bolero-Daph ... B0019M5J5Y

If you crank it so you can hear the intro, the ending will deafen you.

[fossiltooth]

To be fair, I bet that none of us own any recordings -- even classical ones -- that use a full 14 bits of dynamic range.

Telarc's 80's release of Bolero maybe?

If you crank it so you can hear the intro, the ending will deafen you.

Maybe! And the fact that the CD version is capable of doing that (and to a larger degree than vinyl) is one of the many reasons classical and jazz fans were the first to switch to digital. I liked the way this guy put it:

When playing back a CD, the amplifier is usually set so that the quietest sounds on the CD can just be heard above the noise floor of the listening environment (sitting room or cans).

So if the average noise floor for a sitting room is say 50dB (or 30dB for cans) then the dynamic range of the CD starts at this point and is capable of 96dB (at least) above the room noise floor. If the full dynamic range of a CD was actually used (on top of the noise floor), the home listener (if they had the equipment) would almost certainly cause themselves severe pain and permanent hearing damage.

If this is the case with CD, what about 24bit Hi-Rez. If we were to use the full dynamic range of 24bit and a listener had the equipment to reproduce it all, there is a fair chance, depending on age and general health, that the listener would die instantly. The most fit would probably just go into coma for a few weeks and wake up totally deaf.

I'm not joking or exaggerating here, think about it, 144dB + say 50dB for the room's noise floor. But 180dB is the figure often quoted for sound pressure levels powerful enough to kill and some people have been killed by 160dB.

However, this is unlikely to happen in the real world as no DACs on the market can output the 144dB dynamic range of 24bit (so they are not true 24bit converters), almost no one has a speaker system capable of 144dB dynamic range and as said before, around 60dB is the most dynamic range you will find on a commercial recording.

[vvv]

That's awesome.

I shall be quoting that, in my local, soon.