Black CDs

[scarecrovv]

I was just reading this thread about Macs and black CDs, and I had nothing to contribute to it, but I also had never heard of a "black CD". So I googled it and found this. After reading it my reaction was WTF? CDs are digital media. There should be exactly ZERO difference between the data one copy and the next, regardless of the color of the CD. They use extremely powerful error correcting codes for exactly this reason. Right? The people who swear by black CDs are experiencing the placebo effect, right? Information theory still works doesn't it? What are these people smoking, and where can I get some?

[PhoenixEnigma]

This is the same group of people that doesn't see an issue with ~$3000 USB cables and at the same time can't actually tell the difference between Monster Cables and coat hangers. I take anything coming from the audiophile community* with a rather large grain of salt unless backed by double-blind research. I'll eat my hat if you - or anyone you can find - can consistently tell the difference between various colors of CDs by sound alone.

As for what these people are smoking, I'm not sure. Probably vinyl record shavings or something.

*Note that this is different than, for example, people who make their living recording audio. Generally, they know their shit.

[cerbie]

Mostly. For audio playback in old hardware, balance and jitter might be able to do something, but most any decent modern players are going to have the audio buffered, using a clock not based on the moving disc, negating even that possibility. As far as strong error correction, though: no. Data CDs have good ECC, but audio CDs have much less. A few bits lost here or there was not considered a big deal, and they are made in such a way that a proper player can guess close enough that you won't notice an occasional misread sample.

The best audio CDR will also be the best data CDR: the one with the best balance of weight distribution (actual 'balance'), best aligned tracks, best dye, best QC, and best compatibility amongst burners. At this point in time, I think TY is pretty much the only worthy one left (in the old days, it was only them and MCC).

OTOH, if you're worrying about physical discs screwing playback up, why not just rip your collection, and get a squeezebox? Problem solved.

I suspect the slot loading drives are using an optical sensor to check where the disc is, and Apple never bothered to test the drives they were given with black discs. His Ego cannot admit fault, so it won't be changed until a couple generations down the road, when fixing a defect can be spun into a feature that gives Apple a competitive advantage.

[Endless Mike]

It's not like Apple manufactures their own drives (regardless of how they brand them). If there's a problem with them, it's very possibly the supplier's fault.

[SlyReaper]

I was just reading this thread about Macs and black CDs, and I had nothing to contribute to it, but I also had never heard of a "black CD". So I googled it and found this. After reading it my reaction was WTF? CDs are digital media. There should be exactly ZERO difference between the data one copy and the next, regardless of the color of the CD. They use extremely powerful error correcting codes for exactly this reason. Right? The people who swear by black CDs are experiencing the placebo effect, right? Information theory still works doesn't it? What are these people smoking, and where can I get some?

If you were buying a supercar, you wouldn't fit cheap tyres on it would you? Same goes for your data storage media.

Spoiler:

tumblr_lbc28dKuhQ1qav6f6.png (3.32 KiB) Viewed 1050 times

[GeorgeH]

Confirmation bias is a bitch.

If I stand on my head and squint, I can see how it might be possible for black audio CDs to introduce systematic errors into the sound data that subjectively result in better sound. I'd be shocked if that were actually the case, though, and by objective definition that would actually make black CDs sound worse, not better.

[Meteorswarm]

Confirmation bias is a bitch.

If I stand on my head and squint, I can see how it might be possible for black audio CDs to introduce systematic errors into the sound data that subjectively result in better sound. I'd be shocked if that were actually the case, though, and by objective definition that would actually make black CDs sound worse, not better.

More to the point, couldn't you just predict what those errors would be and introduce them to a standard disk? Bits are bits.

[cerbie]

Confirmation bias is a bitch.

If I stand on my head and squint, I can see how it might be possible for black audio CDs to introduce systematic errors into the sound data that subjectively result in better sound. I'd be shocked if that were actually the case, though, and by objective definition that would actually make black CDs sound worse, not better.

More to the point, couldn't you just predict what those errors would be and introduce them to a standard disk? Bits are bits.

No. Bits are bits, but they are only the bits you expect them to be with a perfect reading mechanism, and/or strong ECC. Audio CDs have neither. Memory used to be expensive, so fully buffering everything, allowing for rereads and such, was not an option. I'm sure there are also good reasons for having inferior ECC to data discs, too (possibly length, possibly just a matter of xtors needed for the reader). The guys who came up with audio CDs did know what they were doing, though. If an error couldn't be corrected, the player could interpolate what a given sample should be, with only a small number of them missing.

Even so, you pretty much never read a disc error-free. Just that the overwhelming majority of them are perfectly corrected by the ECC. When you burn, errors are also introduced. A CD with the logo must follow certain standards as to the maximum read error rate in a reader with the logo.

I don't see how you could test it. A burner that can make error-free writes is pretty much a pipe dream. You'd then have to get the raw bitstream read by the player, from both the normal and black CDs. Then, you'd have to figure out a way to perfectly mimic the black CD's bitstream, if significantly different. However, both discs will constantly be throwing errors, but at different sets of bits, based on details of their being read. If the dye and reflective layers are in fact different between the two, testing by disc, with any real control, would be difficult to impossible. All three discs will have plenty of errors (factory pressed, plain CDR, black CDR), and those errors will not always be identical each time each is read.

You could record from the SPDIF, and see if there is a radically different set of errors. In this case, you would actually want four+ samples: a factory pressed disc; one or more normal CDRs, with the burn being corrected for sample offset; the black CDR, also corrected for sample offset; and a verified rip on your PC (EAC or dBPoweramp, with a moderately popular disc, and a good ripping drive), with the audio file to be compared adjusted to match the CD player's read offset (so that you can just invert and merge to get differences, after recording). With this test, be able to switch to the computer playback of a perfect rip as well (without the subject knowing), if including an actual listening test. Just to annoy the subject(s), get a scope, and verify damn low jitter beforehand, or include a correcting mechanism, because that will be the "obvious" source of the difference, if the PCM stream shows no significant differences.

As well, it would be funny if such a test were conducted, a difference was found, and the black one had the most differences from the perfect rip, and the most differences from the factory CD output, such that they were attributing a CD player's guessing of samples to superior playback.

[distractedSofty]

As well, it would be funny if such a test were conducted, a difference was found, and the black one had the most differences from the perfect rip, and the most differences from the factory CD output, such that they were attributing a CD player's guessing of samples to superior playback.

While I agree that it's funny, it's also the most likely explanation (outside of it being all in their heads). Most people agree that antialiased and texture filtered images look better than the alternative, and that basically amounts to degrading the signal in ways that make it look more natural. If pschoacoustics was considered in choosing the interpolation algorithms, then randomly introducing some errors (but not too many) might make the final signal sound better.

[Izawwlgood]

A friend of mine owns a Porch, and went on this long tirade about how he only refuels it at one particular Shell gasoline station because he wants to ensure the same gas blend is always used in his automobile. When asked if he always refueled at the same time of day, during the same temperature conditions, and the same time of the month, he looked at us like we were idiots.

I've definitely heard that on performance automobiles you want to buy your gas from the same company to ensure the same constituents are used in your fuel, but it's probably not that big of a deal when you factor a bunch of other things.

Audiophiles, vinophiles, they're all the same.

[GeorgeH]

A friend of mine owns a Porch

Actually, your friend is right. Porches are very sensitive to gasoline; if you don't handle things correctly, dramatic mechanical failures can result:

Spoiler:

[broken_escalator]

A friend of mine owns a Porch

Actually, your friend is right. Porches are very sensitive to gasoline; if you don't handle things correctly, dramatic mechanical failures can result:

Spoiler:

I upgraded my Porch to cement and brick to prevent such a catastrophe. I fully recommend my fellow Porch owners do the same if you don't feel comfortable handling gasoline correctly.