Audiophile testing - work in progress

Discuss Max, an open source CD audio extractor and audio converter.
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borndevil
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Audiophile testing - work in progress

Post by borndevil » Wed Jan 17, 2007 11:21 pm

I'm an owner of Audiofile HiFi System, here's my set:

CDP: Rotel RCD-02
Pre: NuForce P8
Monos: NuForce Ref 8.02
Speakers: Klipsch Ref 5
Cables: Supra PLY 3.4 + 2x AM-Audio

Well, when I tried EAC in the past I was surprised how things could change with a ripping made in the right way. Records were quite different, before I didn't use Nero but Feurio, one of the best piece of software dedicated to audio only. But there were not competition, EAC was audible, better.

After few weeks I switched to Mac.
I spent so many hours to examine every software could be, if not the same, about near EAC with no success. Every paranoia software based with no exception crashed my powerbook, so I left every test and started to use Toast for some year.

Believe me, Max is what I waited for, an alternative to Toast with paranoia routines that made me try again on the way of best sound possible.

I produce always only one copy from original discs. I never copy from a friend's burned CD as I can't understand how it was ripped AND because every copy is made going to degrade audio signal. This is evident on systems audiophile like mine.

I don't want to enter in the question: is Max really accurate with x ripping mode and y cached/nocached burner

I want just to say that this evening I produced a double copy of my original disc of "Manà", one with Toast, the other with Max.

I can't say, now, what is better, the "better" is an opinion that takes so much time to decide, and 'cause I burned Max cue/bin on a CD-RW that should never be used, but I CAN say that there are EVIDENT different sounds.

I'll report my other tests, hopin' could be useful.

chris31fr
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Post by chris31fr » Wed Feb 07, 2007 10:04 am

And what are your conclusions now ? :wink:

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borndevil
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Post by borndevil » Mon Feb 12, 2007 9:25 am

I'm not sure. Only think I can assure is that at the moment original is the best sound. Some other test revealed that paranoia ripper is not better than Toast. But this sounds strange, even if Roxio routines are optimized for audio copy. Max copy sounds a little "flat", but I really need to test a damaged CD and some other test to have significative results.

chris31fr
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Post by chris31fr » Mon Feb 12, 2007 5:50 pm

It means that Toast is not so bad... :wink: But we don't know it works, with corection or not.. The old toast version had preferences for ripping (corection etc...) but the new one : nothing... :?

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borndevil
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Post by borndevil » Tue Feb 20, 2007 2:34 pm

well, now I'm done with so many tries.
I'm sure that in my system Toast solution sounds better than max :roll:
max ripped copy sounds too flat, with no energy, at least in my configuration. I'll keep you informed

lunax59
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Best sound quality from CD's using Max

Post by lunax59 » Tue Feb 20, 2007 11:31 pm

Hi, after very heavy testing I came to the result, that this combination sounds better than anything available on CD, at least this is what I do:

Cleaning the CD (with window cleaner, for exmple) to remove the smudge from the surface. Demagnetize it with Furutech RD-2 device. Rip the CD with Max and CDparanoia activated to AIFF 24bit resolution, NOT 16bit. Play the music with iTunes and use an AQVOX D/A converter connected via high qulaity USB-cable, NOT Tos/Link. I am using the Formac external DVD burner with firewire interface and a Pioneer DVR111 drive built in.

The result, at least with my system, is that resolution, dynamic and soundstage are on the level of my best SACD's. As soon as I go back to 16 bit AIFF or CD, the magic is gone. This way my Macbook found it's way into my hifi-rack.

Cheers

Peter

goldenratiophi
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Post by goldenratiophi » Mon Feb 26, 2007 9:22 pm

borndevil:

Did you ABX the two? And you're ripping to the same formats (and both lossless), right?

I'm not a hardcore audiophile, and I'm sorry if you're right and I'm not believing you but... CDs are all just raised and flat portions, 1's and 0's if you will. When ripping the CD, the worst that can happen is getting pops and clicks from CD scratches. I don't see how you could possibly be "losing energy" or getting a "flat" response; CDs don't directly store waves like vinyl does. It can't be a rip problem, it sounds definitely like an encoding problem. Or maybe your Mac doesn't have as good a sound card/audio outputs as whatever your other equipment is. Or maybe something else in between.

Basically, my logic tells me that Max can't possibly be the problem. But I'm not trying to start a fight or anything... someone with more expertise than me correct me if I'm wrong. It just doesn't seem right for Max to be casing tonal differences.

Lynne
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Post by Lynne » Tue Mar 13, 2007 2:14 am

Has anyone made any SA or FA graphs to compare the rips made from different apps? I, too, am wondering about the idea of this 'flat' response since I've never heard of that happening because of an audio ripper (assuming all the settings are correct).

Mike1
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Re: Audiophile testing - work in progress

Post by Mike1 » Tue Mar 13, 2007 6:40 pm

borndevil wrote: every copy is made going to degrade audio signal.
I'll pass on the dreadful syntax.

No, it isn't. Music on CDs is digital. This means that either the copy is faithful or it is not. Errors can creep in with any copying process, but there is no such thing as an inevitable and progressive degrading with copying when the copies are digital. You simply don't know what you're talking about. And no one need take any notice of any unsupported and unscientific claims you might make. In fact, after this comment alone no-one need read further.

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Fuga
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Post by Fuga » Tue Mar 13, 2007 10:07 pm

Agreed. I had my doubts with the first post in this thread, but successive degeneration? Sheesh.

goldenratiophi
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Re: Audiophile testing - work in progress

Post by goldenratiophi » Tue Mar 13, 2007 10:50 pm

Mike1 wrote:
borndevil wrote: every copy is made going to degrade audio signal.
I'll pass on the dreadful syntax.

No, it isn't. Music on CDs is digital. This means that either the copy is faithful or it is not. Errors can creep in with any copying process, but there is no such thing as an inevitable and progressive degrading with copying when the copies are digital. You simply don't know what you're talking about. And no one need take any notice of any unsupported and unscientific claims you might make. In fact, after this comment alone no-one need read further.
Actually, I think he was referring to the fact that repeatedly re-encoding lossy files (like ripping a cd burned from mp3s and encoding again to mp3) degrades quality, which is true. But yes, if it was burned lossless, it is identical.

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borndevil
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Post by borndevil » Mon Apr 02, 2007 6:44 am

oh, well. sorry, I was busy so I couldn't answer.

here I copy/paste from cdr faq, but first, basically, differences between two drives or two rip programs is related on how the relationship of hardware/ripper/burning/media work. audio ripping is a subtle, unstable thing. maybe some other have different results. I'll give a try to AIFF 24bit resolution...






"Subject: [4-18] Why doesn't the copy of an audio CD sound the same?
(1998/04/06)

There are actually two questions here, so I've split them into separate sections. The most common problem is that the audio extracted to the hard drive doesn't quite match the original.


Subject: [4-18-1] Why doesn't the audio data on the copy match the original?
(1998/04/06)

Most problems are due to poor digital audio extraction from the source media. Some CD-ROM drives will return slightly different data every time an audio track is read. Others, like the Plextor line (e.g. 4Plex, 8Plex, and 12Plex, but not 6Plex) will return the same data every time so long as the source media is clean.

The most fundamental problem is that, if the CD is dirty, the error correction may not be able to correct all of the errors. Some drives will interpolate the missing samples, some won't.

Another problem some CD-ROM drives face is "jitter". See section (2-15) for details.

See also section (3-3) on avoiding clicks in extracted audio, and section (5-5) on which CD-ROM drives are recommended.


Subject: [4-18-2] The audio data matches exactly, why do they sound different?
(2004/12/10)

Suppose you extract the audio track from the copy, and it's an exact binary match of the track you wrote from your hard drive, but the CDs don't sound quite the same. What then?

Most people don't notice any difference between originals and duplicates. Some people notice subtle differences, some people notice huge differences; on better CD players, the differences are harder to hear. Some say CD-R is better, some say worse. While it's true that "bits are bits", there *are* reasons why CD-Rs may sound different even when the data matches exactly.

An excellent paper on the subject is "The Numerically-Identical CD Mystery: A Study in Perception versus Measurement" by Ian Dennis, Julian Dunn, and Doug Carson, submitted to the Audio Engineering Society (Preprint 4339, 101st AES convention). It's available for download in PDF form at http://www.prismsound.com/m_r_downloads/cdinvest.pdf. The paper is primarily concerned with why pressed CDs created at different plants or with different methods sound different, but the observations are relevant to CD-R as well.

The conclusions in the paper suggest that low-frequency modulations in the disc affect the servo and motor electronics, causing distortion noticeable to a critical listener.


One prominent theory is jitter. This isn't the DAE "jitter" described in section (2-15), but rather a timebase error. A good overview can be found in the jitter article on http://www.digido.com/. A brief explanation follows.

The digital-to-analog ("D/A") conversion at the output of the CD player is driven by a clock in the CD player. The clock is tied into feedback mechanisms that keep the disc spinning at the proper speed. If the digital signal being read from the disc has irregular timing, small errors can be induced in the output clock. Even if the CD player gets all of the digital bits accurately, it will produce inferior results if the timing of the bits on the disc isn't precise. Put another way, something has to send a sample to the speakers 44100 times per second, and if it's speeding up and slowing down many times each second your ears are going to notice.

There is some question as to whether the clock driving the output will actually be affected by the input. If the output clock in the CD player is isolated and stable, jitter from the CD will not affect it.

If you play a CD digitally (e.g. by ripping it and then playing it through a sound card), the quality of the CD doesn't matter, because it's the timing of the clock in the sound card that drives the D/A conversion.

It has been asserted that the clocking of bits on a CD-R isn't as precise as on a pressed CD. Writing at different speeds on different types of media requires adjustments to the "write strategy" (section (3-31)) that can result in individual "marks" being sloppier than at other speeds. This could account for inferior -- or at least different -- sound.

Yamaha believes they have found a partial solution for jitter problems with their Audio Master Quality feature. See section (2-41).

There do not appear to be any carefully constructed (double-blind) tests published on the web that confirm that jitter is the cause of this phenomenon. The "Numerically-Identical CD Mystery" paper rejects jitter as a possible cause.


Some people have asserted that *any* two CDs, pressed or otherwise, will sound slightly different. Some claim to hear differences in identical CDs from different pressing plants. The former is silly, but the latter has a lot of anecdotal evidence to support it.

The manual for the CDD2000 reportedly states that the drive uses 4x oversampling when playing pressed CDs, but switches to 1x for CD-R. This affects the quality of the D/A conversion, and can make an audible difference.

http://www.mrichter.com/cdr/primer/losses.htm has some further thoughts, including a table showing signal level differences.

An extremely technical introduction to CD reading is available at http://www.tc.umn.edu/~erick205/Papers/paper.html. This may shed some light on why reading audio CDs is difficult, as well as explain concepts like aliasing and dither.

If you are finding your CD-Rs to be noticeably inferior, try different media, different write speeds, a different player, or perhaps a different recorder. There is some evidence that different brands of media and recorders may work better for audio, but in the end it's a highly subjective matter. Some people say CD-Rs sound worse, some people say they sound better (and some people think vinyl records are still the best)."

ebernet
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Your post

Post by ebernet » Fri May 11, 2007 10:32 pm

Your post was about the quality of burns, and how CD-r burns are not all as easy to read for audio playback as a pressed CD. What that sounds like is that extracting audio from a burned CD might not be as accurate as from a pressed CD, so how to maximize the best quality burn from a read...

I would argue, use the best brand CD-r media (I use Taio Yuden [sp.]), burn at the slowest possible speed. I don't think ripping it to a resolution that the CD did not have to begin with (24 bit) will somehow improve your copy. If anything, I think that would degrade it or add noise that was not there (you are making up information when you do that)

Kees de Visser
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Re: audible differences

Post by Kees de Visser » Tue May 22, 2007 8:24 pm

As stated earlier in the thread, before you do any listening it's essential to verify if the audio data are identical. If the data are different, there is some problem in at least one of the ripping procedures.
If different cd's with identical data sound different on your system, the system is broken. You are probably using a DAC that is not capable of reproducing audio data correctly. With a DAC that is running on a stable (internal or external) clock, jitter should be no issue.
You could try to borrow or rent a high quality external DAC. The audible difference should disappear (in a double blind test) :)

floatinglist
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Post by floatinglist » Sat May 26, 2007 6:29 pm

I have forgotten all about this stuff!

Yeah, the audio signal usually degrades over a cycle of successive burns and rips because audio CDs have poor error correction relative to the capabilities of data CDs. (Note that audio CDs hold more data than data CDs when full because the data CDs use more bits for error correction and only a few more for filesystem overhead.)

The poor error correction (which seemed robust when the CDs were first produced) becomes an issue because of the way CD media is easily damaged, and the way writable CD media degrades quickly compared, to say, the way a book degrades over time.

The relatively poor error correction allows for CD drives to choose how much work is done to ensure data is read correctly, and errors are accounted for. There is no way to ensure a rip is 100% accurate unless you compare checksums of your copy with checksums of the copies of others'. This is why I no longer use audio CDs except for import. If I need to carry a perfect copy of a rip, I'll encode it as FLAC, then burn the FLAC file to a data CD (or copy it to a flash drive or other portable storage).

If you have an original, pressed CD, then making sure it is clean helps ensure you will get a 100% rip. If you have clean writable media, you probably will get a 100% rip. CD-Rs degrade over time, but, for the first decade, whether or not your media will degrade is hit or miss (though a brand or two have a reputation for having a lower probability for degrading in the first decade). (I write decade because, even though CDs are technically good for about a century, it is known that CD-Rs usually degrade more quickly, and CD-Rs have only been widely used for a decade.)

If you have a dirty pressed CD, or a CD-R of questionable status, you might be able to get a 100% rip, but you are at the mercy of CD drives. Problems with drives include poor implementation of error correction, poor reporting (or recognizing) of L2 error codes to software, or an always-on caching system (in the drive) that prevents software such as cdparanoia from properly detecting and re-reading bad sectors.

Here is more info about the problems with ripping:
http://xiph.org/paranoia/faq.html#play

In short, if you ever have to rip your library, or send your discs to a ripping service, make sure that the discs are cleaned, and that you (or the service) will try to remove scratches on the disc rather than trusting ripping software (even cdparanoia) to make good corrections.

Oh, if you try to rip a CD to 24/96, you might change the sound of the audio. This would be great if you're going to edit the music, but it won't change the fact that audio CDs will always be in the 16-bit linear raw PCM format.

For the original poster, try ripping the same CD with the two programs to the same format. Then, compare the two files' checksums. [1] I don't know if this will work because Toast or Max may write an extra bit or two to the header. (This won't tell you what percentage of the files are the same, and I don't know of a good program for telling what percentage of large audio files are the same.)

[1] You can use this program: http://www.entropy.ch/software/macosx/#checksum (This program simply uses a program installed on all Macs by default—OpenSSL.)

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