Audio Myths.. food for thought

I don’t now how the US rips and if it uses something like AccurateRip. (Which in case you don’t know, compares the rips of a CD between everyone who ripped it).

And if you compare not the playing CD and a rip, but two different rips, then I don’t see how the US could have an influence

Sorry now I was not precise. You are right of course. I meant “noise” in the more general sense of data noise. Not just electrical noise but noisy data that gets created if the error correction during reading is overwhelmed. That could translate into a rip IF you allow the ripper to continue in the presence of uncorrectable errors (i.e. interpolated data) AND IF you are not using something like AccurateRip. I.e., if the rip is not bit-perfect. But as it is easy to create either bit-perfect rips or abort on any bit error, why would you

Ok what i think we could do, is that @TOBYJUG could copy both rips from the Unitiserve and place them online somewhere, then we can do some waveform comparisons to see if there are differences that could explain what he’s experiencing. :slight_smile:

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How should I go about that ? I’m not particularly tech savvy. I haven’t even worked out how to download albums in the download folder. Plus I don’t have any nas backup system in place.
I have a mac book. iPad and iPhone.

An md5 checksum would be easier and more reliable. However with flacs one would have to control for tags at least. WAV would be less ambiguous

Yes true, i was thinking in case the files are not identical…

I found this other thread on the forums:

If that helps you to get the files on your Macbook, then you will have a good starting point to do some tests!

Sure, but I believe we can assume they are. If they are not, then at least one of the rips is faulty wrt to accuracy and then the problem becomes less interesting. If both rips, with and without wonder fluid, produce bit-perfect, indistinguishable files but sound different, that’s what would blow my socks off

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Haha, i would think the other way around. If they are identical then the most likely conclusion would be that it is caused by a listening bias. If they would be significantly different however to such a degree that it changes the tonal qualities of the rips, that would be very interesting i think!

OK, seen from this perspective it would indeed be interesting in a sense. It’s just that the fact that two demonstrably different files are, well, different, would not be quite the sensation :wink:

Afterthought: If there is a lot of interpolation going on caused by constant [uncorrectable but] non-fatal reading errors, original data is lost in a way that is not totally different from mp3. And lower-bitrate mp3s have such a loss of stage, realness, shimmer, body, and so on

Edit: Something that should maybe mentioned for the benefit of those who never in their life nerded out on CD data encoding: There are constant read errors by the laser when reading a CD. The only reason why this works at all is because of redundancy in the data encoding and hence the ability to reconstruct data perfectly

You could be a marketing agent for magic cleaning fluid @Suedkiez :stuck_out_tongue:

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They could have made a fortune in the 90ies by providing a CD fluid that makes Windows and Office not crash when installed from a treated CD

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How did you manage to compare the two rips? If you rip the same CD twice on a US, I seem to recall that it replaces the first rip with the second, and you need to do a bit of jiggerypokery to get around this.

Let’s consider two scenarios.

Data is copied from a CD in such a way that there is no error in reading the data, it is read perfectly from the CD.
Would the data be written to a particular single part of the hard drive, which when read would produce only a little electrical noise.

Data is copied from a CD in such a way that there is error in reading the data, and error correction is performed during the rip.
Would the data be written to various parts of the hard drive, which when read would produce more electrical noise.

I always rip to my PC then copy to a NAS, then stream from the NAS. So I wouldn’t have this problem, if it actually exists. :innocent:

I think that allowing too much room for hypotheticals, without clear ways of testing and verifying any provided claims, is what leads to Audio Myths being created and perpetuated. Any difference in sound that is large enough to be audible by human ears, should in principle be more than large enough to be verifiable in objective tests. If it isn’t and we are stuck in the magical / unexplained realm, then we risk perpetuating ambiguous truths that in the long run will hurt our collective goal of reaching the best possible sound reproduction using objectively effective tools and methods.

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Maybe Tobyjug ripped the cds again, after the cleaning, and found they sounded better than before ?

They both came out as unknown. The first had me writing in the metadata. The second rip didn’t transfer to the first but came out as another unknown. As far as I could tell they were both unknowned by the same look up.
Unknowns do pop up every now and again when ripping new discs, this is when I’ll take the opportunity to try this scenario.

So no AccurateRip check, as that only possible if known.

So could rips “authenticated” by different look ups sound like something other than what’s on the disc ?
If so how should I know which is the most accurate ?

Yes the first test would be an md5sum check as @Suedkiez suggested, this would tell if the rips are identical. On a mac you could do this from a terminal window:

md5 [file1.ext]
md5 [file2.ext]

Both should give back the same result (hash).

If there is a difference, it could be interesting to open both files in an audio program to compare the waveforms. An option could be to install a trial version of a paid program like ReSample:

It is beyond me.

I rip on a computer using dBPoweramp, which links with AccurateRip to compare with a database of rips, and if not identical then re-ripping more intensively often achieves it. They have rip data on something like 400 million CDs, and it is rate to find one not in their database.