Optical drive

[kumakuma]

Conclusion:

If all the ripping software are equal the drives are not.

You have a better result with single wavelength drives avoid high aperture ones.

Regulated power is a must have.

Avoid slim drives and slot ones.

Avoid heat, a pause between two CD's when you rip is welcome.

And don't forget the optical drives are not designed for audiophiles

 

When you refer to "better result", are you referring to better sound quality when playing a CD, better ripping performance (less errors), or rips that sound better?

[kumakuma]

Please don't, even though it only interests people who don't already know everything, and want to learn rather than argue.

 

+1

 

BTW, this thread might be more active if you could explain things in simpler terms for idiots like myself.

 

For example, you seem to imply that Alex's observation that identical data stored on a hard drive can somehow sound different but I can't see the explanation based on the references you provided. Can you help us connect the dots?

 

I would like to believe that Alex is right but so far no one has come up a plausible explanation.

[kumakuma]

Tom I never said that identical data may sound different, I say identical checksum may sound different.

in the statement I also said that CRC is independent of data values.

 

I guess this is the part that I am missing.

 

For example, Alex provided me with two files that he insists sound different. I calculated the checksum of both files and did a byte by byte comparison of the files and as far as I can tell they are identical. Are you saying that they may be different?

[kumakuma]

I understand, you are talking bit and Im talking sample value, ok take an example for a 3T pit you may have a smaller amplitude in the read out signal due to the length effect but you still represent it by 001.

 

This matches my understanding. The signal may have a lower amplitude but there is no mechanism for capturing this lower amplitude in the digital data that is written to the HDD when the CD is ripped.

 

It is also my understanding that there can only be two types of rips: one that match the binary data on the CD (correct ones) and ones that don't (incorrect ones).

 

Alex has observed rips that seem to fall between the two. They are correct and identical to each other at the binary level but the quality varies according to the power supplied to the drive during the ripping process.

 

I don't believe that such rips can exist. What do you think?

[kumakuma]

We didn't finish to link the dot,3T is the smallest value but if you have a smaller amplitude in the read out signal what will happen to a 4T? you will read it as 3T than it's represented by 001 instead of 0001.

when we will go further in explanation with sector, data chunk , block error read,splicing in checksum you will understand that's why I told it need a demonstration.

 

If the amplitude drops below the threshold level and the data changes from 0001 to 001, this will be a read error and, if this error is uncorrected, the resulting rip will have a different checksum than a rip in which the data didn't change from 0001 to 001, right?

[kumakuma]

In theory yes, but real data are different animals.

 

I understand that it is possible for different files to have the same checksum but the chances of this occurring in the situation are so small that I think we can ignore this as a possibility. Also, as I mentioned above, I compared the data at the byte level and found it to be identical.

 

Alex has said that you have proposed phase shift and the hall effect as reasons why identical data files may sound different. I am having a hard time with this as I believe these factors are only applicable when data is being read from the CD. Once the CD has been ripped, there is only binary data and these factors don't come into play. Is my understanding incorrect?

[kumakuma]

No my message was phase shift=same checksum=different sound.

 

Can you explain what this means?

 

Is this also true?

 

phase shift=same bits on the HDD=different sound

[kumakuma]

No didn't say the same bits in HDD=different sound.

As said already that I will explain my findings.

 

Thanks for the clarification. I look forward to hearing more when you are ready.

 

All the best,

 

Tom

[kumakuma]

Tom,

 

Just for clarification I never said and will never say that identical bits sound different, I just tried to find out why Alex and others can hear a difference.

I could see only two possibilities the data are spread on different packets that may affect the bit rate(BER) or it make the jitter higher during the reading process or the non uniformity of the checksum is the culprit.

I had to start first with the behaviour of the optical drive to try to explain what happening first and if the two possibilities can be covered.

So please let's forget about the bits are bits war, and let's continue to try to find what is behind the mathematical assumptions.

And anyhow if at the end you are not convinced by my demonstration I'm sure that in any case you are learning stuff about the optical drive:)

 

Thanks again for clarification.

 

I am looking forward to your demonstration.

 

For the record, here is what I believe on this subject:

 

- There are only two kinds of rips: ones that match the data on the CD (accurate rips) and ones that don't (inaccurate rips).

 

- It is not possible to have a "better sounding" accurate rip or two accurate rips that sound different. All accurate rips that are bit-identical should sound the same when played through the same playback chain. If they don't, the cause is external to the data itself. An example would be HDD fragmentation.

 

- A better quality CD drive or better power to an existing CD may improve playback quality. It may also make it easier to obtain an accurate rip by reducing read errors, etc. It will not result in a better sounding rip if the rip is accurate.

[kumakuma]

13 minutes ago, Ralf11 said:

identical checksums may sound different, but would that depend on which particular bits differ while yielding the same checksum?