CD transport into Apple Mac

[Marco]

Tony,

As far as CDROM drives go, yes to a certain extent I'd agree that with multiple reads (EAC or similar) then it may be possible to eliminate most of the errors in reading from CD. Within reason! Some CDROM drives are total rubbish!

I totally agree. It also goes against the grain, for me anyway, to use some cheap plastic transport design in any digital application - I would always use something solid and beautifully engineered even if it just felt nicer to use!

Marco, I'll bring my CDPro2M along to ChesterFest and you can listen to it on your DAC if you like?

Bring it on, Tony. I'd love to hear it and your own DAC, too - looks great

TDA1541 chips rule!!

Marco.

[NRG]

I think there is a bit of confusion here.

You can get CD based music onto the Mac/PC in two ways, play the analogue output from a CD player (high end Dedicated or whatever) into a soundcard (ADC) and store it on to the computer or perform Digital Audio Extraction of the CD data direct onto the harddrive.

DAE is by far the best way to go, it eliminates the DAC and ADC steps and also has the benefit of supporting C1 and C2 error correction and detection. Many many dedicated audio CD players do not perform C2 error correction.

Yes, it's true most Computer based CD players (well they are all now DVD players) are plastic things that play Red book CD via analogue in a most pitiful way but....they perform DAE in a very accurate and reliable manner and they will produce a better copy of an Audio CD using DAE than any high end dedicated audio CD player can because of the DAE process.

Oh and BTW I read it many times on the boards that the data from CD's are read as one's and zeros....not true, the data stream from the raw cd is not a square wave, it's more like an analogue signal or more accurately an RF sinusoidal EFM signal. But is does contain the information to reproduce the original data...

[Marco]

Yes, it's true most Computer based CD players (well they are all now DVD players) are plastic things that play Red book CD via analogue in a most pitiful way but....they perform DAE in a very accurate and reliable manner and they will produce a better copy of an Audio CD using DAE than any high end dedicated audio CD player can because of the DAE process.

Hi Neal,

What exactly is the DAE process?

I'm not qualified to dispute the above, but has anyone actually done the comparison and listened to the results?

You see, I'm an old-fashioned guy, and fancy technical terms and 'scientific facts' in audio mean little to me unless I hear the results myself through a hi-fi system with music. I don't automatically 'accept' any effect in audio until I have judged it through that process.

As such I would love to do a test using a top-notch Red Book CD transport and a computer based one in respect of the above to see if I could hear any difference in the results obtained. If I could genuinely hear no difference then I will have learned something and we will be in full agreement.

Perhaps we could do this at the Chesterfest?

Marco.

[Mike]

Hi Neal,

What exactly is the DAE process?

LOL!... Marco, think of it like this:

There is no music on a CD, only DATA, stored as one's and zero's. It only becomes music once processed by a DAC.

The trick here is to transfer that raw data as accurately as possible onto a hard drive, this is where multiple passes (the number of times the disk is read) and error detection and correction comes in. With DAE you can take as long as you need/want doing this process to get the data from the CD with as few (if any) errors as possible. An error is reading a '1' as a '0' and vice versa.

Listening to it 'live' or converting it in 'real time' (ie. as it's playing) is a different matter, the transport has only one chance to get it right, any error detection and correction has to be done 'on the fly'. A much more tricky prospect.

A very simplistic (and possibly rubbish) explanation.

[Marco]

No that's absolutely fine, Mike. I understand - cheers

I'd still like to *HEAR* the results myself, though (somehow).

How was yer sleep - any nice dreams?

Marco.

[Mike]

How was yer sleep - any nice dreams?

Marco.

No dreams that I can remember, slept like a dead body. Didn't get up till 5:30pm so I'll probably not be able to sleep tonight either.

[Filterlab]

LOL!... Marco, think of it like this:

There is no music on a CD, only DATA, stored as one's and zero's. It only becomes music once processed by a DAC.

The trick here is to transfer that raw data as accurately as possible onto a hard drive, this is where multiple passes (the number of times the disk is read) and error detection and correction comes in. With DAE you can take as long as you need/want doing this process to get the data from the CD with as few (if any) errors as possible. An error is reading a '1' as a '0' and vice versa.

Listening to it 'live' or converting it in 'real time' (ie. as it's playing) is a different matter, the transport has only one chance to get it right, any error detection and correction has to be done 'on the fly'. A much more tricky prospect.

A very simplistic (and possibly rubbish) explanation.

In fact that's an excellent explanation.

Half the problems with computer based audio is that many programs (iTunes included) import on a straight rip; i.e. importing the data once and running it through an error correction system - the same as a straight replay from a CD player. With certain import programs, programs that are specifically designed for complete error free importing (like Max), multiple passes of the CD are taken. The software then averages the data omitting any data that isn't original (error corrected data for example) and replacing it with the true data from another pass.

To put it another way, if you have ten identical cars all with some damage on them, by using only the good parts from each car one should easily be able to make a perfect car with no faults. This is what multiple pass software does. Of course, most CDs owned by audiophiles are unlikely to have damage extensive enough on them to require more than three passes, but in the case of buying secondhand CDs up to ten may be necessary to get as clearer data as possible.

This is where imported music has a distinct advantage over a CD player, a CD player is doing everything on the fly, reading the disc, coping with external forces, correcting errors with what it 'thinks' should be in place, sending the data to the DAC, decoding in the DAC and converting the signal to analogue. In essence it's like asking a musician to play a tune whilst it's still being written by the composer rather than the composer providing a printed sheet of music.

This is why the quality of the transport used for import is not as critical as one used for immediate replay. The CD player has one chance to get it right and must do it time and time again with as few errors as possible, an import on the other hand may take several minutes as might the decoding process, but it has multiple times to look at the data and get it perfect (or as perfect as) before finalising it in the form of a stream of correct 1s & 0s. Once this has occured the reading of it is faultless EVERY time and there's no mechanical interface to interfere with its replay.

[Marco]

Another excellent explanation. Thanks for that, Rob.

All seems clear, but I'd still like to do the test though, as I've outlined, to hear whether in reality what you're saying is actually the case. Sorry, it's just the way I am

Marco.

P.S Did you get my mail about the smileys?

[Filterlab]

Another excellent explanation. Thanks for that, Rob.

All seems clear, but I'd still like to do the test though, as I've outlined, to hear whether in reality what you're saying is actually the case. Sorry, it's just the way I am

Marco.

P.S Did you get my mail about the smileys?

Well, for me it took actually hearing it to nail the revelation home - you were there at the time. Since then though I've learnt a lot more about the subject and had the chance to try oodles of different combinations of software that's made the world of difference.

Yep, got your email. Replied twice but it just bounces back. Have you got the trampoline out again?

[NRG]

Hi Neal,

What exactly is the DAE process?

I'm not qualified to dispute the above, but has anyone actually done the comparison and listened to the results?

You see, I'm an old-fashioned guy, and fancy technical terms and 'scientific facts' in audio mean little to me unless I hear the results myself through a hi-fi system with music. I don't automatically 'accept' any effect in audio until I have judged it through that process.

As such I would love to do a test using a top-notch Red Book CD transport and a computer based one in respect of the above to see if I could hear any difference in the results obtained. If I could genuinely hear no difference then I will have learned something and we will be in full agreement.

Perhaps we could do this at the Chesterfest?

Marco.

Mike has nailed it pretty much Marco. And no offence but you are a Luddite

It's not scientific fact, it's common sense....keeping the digital data in the digital domain for transfers is the best way to go. Each time you perform ADC and then DAC you will introduce errors, noise artifacts etc.

If you believe in the 'simple chain is best' rule for audio quality and the 'rubbish in = rubbish out' philosophy then you'll see DAE is the only way to go for the best copy and therefore best sound quality when ripping to HDD.