Essential technical specs for cd transport ONLY

[KellenVancouver]

I know this sidebar comment will draw criticism, but the "transport only" part of this thread sort of stuck with me. I don't get how the audio world "advanced" by transitioning CD players from one piece of gear, with incorporated DAC, into two separate components. From the perspective of technological evolution, that seems rather backward. I get it as a marketing ploy to leverage more dollars out of consumers, but do 1s and 0s seriously perform better when those components are separated? Cambridge Audio has this to say about CD Transports: "Connecting to an amplifier or DAC via the digital output means that the signal remains in its original digital form for as long as possible, unlike traditional CD players. As the signal remains digital and turns analogue at the very last minute and with a minimum of extra cables and connections, the signal will suffer less from analogue signal deterioration." Putting aside the awkwardness of using a phrase like "last minute" for a process that takes microseconds, is this just hype or is it a real issue?

 

[antcollinet]

Ripping cd to digital files degrades fidelity.

I buy a lot of cheap cds from people like you, thanks.

No, it doesn't

 

[Kal Rubinson]

Putting aside the awkwardness of using a phrase like "last minute" for a process that takes microseconds, is this just hype or is it a real issue?

Not a real issue.

 

[KellenVancouver]

Not a real issue.

Thanks for confirming Kal! I'm glad my "spidey sense" was on the right track.

 

[Willem]

It is indeed not a real issue. However, the good news is that if you already have a good DAC you can use a dirt cheap cd/dvd/BR player as a drive, as long as it has an optical or coaxial digital output (not all of them do anymore).

 

[xaviescacs]

Ripping cd to digital files degrades fidelity.

No bits are lost due to the copy. What you do with them afterwards it's not my business.

I buy a lot of cheap cds from people like you, thanks.

Great times for used CD market!

 

[MCH]

I know this sidebar comment will draw criticism, but the "transport only" part of this thread sort of stuck with me. I don't get how the audio world "advanced" by transitioning CD players from one piece of gear, with incorporated DAC, into two separate components. From the perspective of technological evolution, that seems rather backward. I get it as a marketing ploy to leverage more dollars out of consumers, but do 1s and 0s seriously perform better when those components are separated? Cambridge Audio has this to say about CD Transports: "Connecting to an amplifier or DAC via the digital output means that the signal remains in its original digital form for as long as possible, unlike traditional CD players. As the signal remains digital and turns analogue at the very last minute and with a minimum of extra cables and connections, the signal will suffer less from analogue signal deterioration." Putting aside the awkwardness of using a phrase like "last minute" for a process that takes microseconds, is this just hype or is it a real issue?

My 30 year old Sony CD transport (without DAC), that I still use, was originally part of a system in which it was connected to a DSP that had EQ and various analog and digital inputs and outputs. I think it made sense to put the DAC in the DSP box, not in the CD player. Just an example.

 

[73hadd]

@Doodski , thanks for answering the "essential technical specs" question, by advising about the eye pattern. I am going shopping for 100mhz+ scopes because I want to look at eye patterns from various transports. I also want to measure jitter but short of AP gear I am not sure what to do. @DonH56 tried to help me about jitter measurement but his data rates and applications are.... not applicable! (to this low bandwidth.)

CD Transport thoughts-

I am late to the party on the coolest projects from 16+ years ago. My favorites are:

-Use an IDE CD ROM with a controller/remote control/display that can (still) be bought from ebay
--SPDIF out is 5v TTL and not "normal" SPDIF, so some external circuit is needed or:
--Use a Toslink transmitter, that provides additional benefit of galvanic isolation
It would be fun to compare eye patterns of those two output versions.

-Build a transport based on Philips CD-Pro2
--Would be nice to have an i2s out from this too. Not sure what modern dacs will accept 48fs.
--Would be cool to control DSA from arduino or something.

As for modern CD transport, I like the Cambridge CXC because there are a lot out there, so maybe parts will be available for a while. Can't wait to see that eye pattern!

@restorer-john - your thoughts on TEAC VRDS?


As for ripping CDs with EAC, this is informative:

CD Drive Accuracy 2019

AccurateRip collects data from all drives, normally this is only used to verify a disc is accurate, but can be reversed to calculate which drives are the most accurate (as measured by lowest % inaccurate tracks). This test was previously run in 2016, 2014, 2013, 2012, 2010, 2009 and 2006, as...

forum.dbpoweramp.com

It shows that those who ripped CDs without paying attention may have ended up losing 9% of their accuracy?
Those who say, "you will not notice." Please forward to me (or @amirm) 9% of your money. Yes, maybe "you will not notice" that either, but it would be appreciated.

Perhaps the offending CD ROM drives have an issue with laser, clock, circ implementation, ide or sata implementation, or who knows.

This does prove that optical disc data extraction is fallible. Why lose 9% accuracy if you don't have to?

 

[restorer-john]

@restorer-john - your thoughts on TEAC VRDS?

I don't love it. But the mech and the drive isn't bad. Nobody touches the Sony linear driver mechs, but again, it's the nylon that fails. Guides, glides and pivot/bearings made of nylon eventually crack.

Even the pivot bearing CDM-0/1/1mkII fail eventually.

 

[TheBatsEar]

I can't imagine a good excuse for really worrying about this and not ripping your CDs to get rid of all those problems inherent to hardware based, real time CD playback.

A CD is perfect for many that just want the music, open the tray, put in the disk, music appears. Very easy to learn too, children age 4 can do it. Try to teach your grandparents about DLNA sinks and you might agree.

As for me personally: ripped, all of it, except the stuff bought recently.

I'd be interested any recommendations for CD readers that are better at ripping. Especially difficult CDs. I have a few CDs that failed ripping even though there seemed to be little damage to the surface.

I just keep a few different drives in a drawer. Sometimes i'm able to read a hairy CD with an old Samsung burner, sometimes with a noname USB DVD drive. Just make sure to verify with EAC, which, sadly, noone told me when i started ripping my collection years ago. I'll have to redo it sometime, just to be extra sure.

It shows that those who ripped CDs without paying attention may have ended up losing 9% of their accuracy?
Those who say, "you will not notice." Please forward to me (or @amirm) 9% of your money. Yes, maybe "you will not notice" that either, but it would be appreciated.

Jokes on you. I'm so poor, you wouldn't notice my 9%.

 

[TBone]

I know this sidebar comment will draw criticism, but the "transport only" part of this thread sort of stuck with me. I don't get how the audio world "advanced" by transitioning CD players from one piece of gear, with incorporated DAC, into two separate components. From the perspective of technological evolution, that seems rather backward. I get it as a marketing ploy to leverage more dollars out of consumers ...

... when cd first became popular in these hills, all 1 box players, except the rare (iirc, cambridge).

... then as tradition, a flood of separates soon appeared claiming superior sq. third party tools (like digital lens) also entered the frey.

... for a time, "high-end" stores all had totl separate systems to sell, the lowly 1 box cdp relegated to lower end/cost status.

... the pendulum swings, soon expensive 1 box cdps competed for the high-end dollar ... tho ... ime ... it still seemed that peeps preferred "rolling" expensive digital separates, like tubes, searching for some magic synergistic ...

 

[DonH56]

I think that the catch with the dBpoweramp (AccurateRip) data is there is no way to reconcile if it is really the drive or simply a bad/dirty CD (I have had a number of those). I remember asking them about that years ago (I am a user) but do not really recall the answer (not sure there really was one; it is a lumped data point for each drive). In any event, error correction is built into the CD format, so disc read errors do not necessarily translate into data loss going into the DAC. That said, drives are pretty cheap, might as well get one scoring high on their list.

 

[73hadd]

I don't love it. But the mech and the drive isn't bad. Nobody touches the Sony linear driver mechs, but again, it's the nylon that fails. Guides, glides and pivot/bearings made of nylon eventually crack.

Even the pivot bearing CDM-0/1/1mkII fail eventually.

Thanks! We should 3D print all the nylon parts! (but I don't have a printer)

Are parts (laser diodes) available, or simply not needed as they are almost a "last forever" part?

If I go to the large list of DACs and Transports, what Sony model (a linear one that you like) should I reference, to find all the models using a specific mech/laser?

 

[73hadd]

I realize what I am looking for. A "CD transport accuracy list" like the Accurate rip drive list. Have a disc with a known number of bits. Run it through the laser/buffer/output and compare the "checksum". Score drives accordingly. Maybe some variations:

1. SPDIF output, no clock recovery. Tests the whole signal chain for those with older dacs.
2. SPDIF output to SOTA clock recovery, to see if any bits did not make it to the output wire.
3. Catch the bitstream at i2s or somewhere else on the board? Finds issues that could be corrected with better spdif/toslink implementation.

Regarding CIRC, I do not know how it works so I will ask, shouldn't CD ROM drives be able to leverage CIRC, to a degree that all drives would perform about the same? For example, I bet these drives never failed to copy Windows 95 (because the error correction is different.)

 

[mansr]

Regarding CIRC, I do not know how it works so I will ask, shouldn't CD ROM drives be able to leverage CIRC, to a degree that all drives would perform about the same?

All drives have to do the CIRC decoding, and there is only one way to do it. Audio only or CD-ROM makes no difference. Data tracks have an additional error correction layer since the reliability wasn't deemed quite sufficient for data storage without it. This is not involved when reading audio tracks, though.

 

[jsrtheta]

@Doodski , thanks for answering the "essential technical specs" question, by advising about the eye pattern. I am going shopping for 100mhz+ scopes because I want to look at eye patterns from various transports. I also want to measure jitter but short of AP gear I am not sure what to do. @DonH56 tried to help me about jitter measurement but his data rates and applications are.... not applicable! (to this low bandwidth.)

CD Transport thoughts-

I am late to the party on the coolest projects from 16+ years ago. My favorites are:

-Use an IDE CD ROM with a controller/remote control/display that can (still) be bought from ebay
--SPDIF out is 5v TTL and not "normal" SPDIF, so some external circuit is needed or:
--Use a Toslink transmitter, that provides additional benefit of galvanic isolation
It would be fun to compare eye patterns of those two output versions.

-Build a transport based on Philips CD-Pro2
--Would be nice to have an i2s out from this too. Not sure what modern dacs will accept 48fs.
--Would be cool to control DSA from arduino or something.

As for modern CD transport, I like the Cambridge CXC because there are a lot out there, so maybe parts will be available for a while. Can't wait to see that eye pattern!

@restorer-john - your thoughts on TEAC VRDS?


As for ripping CDs with EAC, this is informative:

CD Drive Accuracy 2019

AccurateRip collects data from all drives, normally this is only used to verify a disc is accurate, but can be reversed to calculate which drives are the most accurate (as measured by lowest % inaccurate tracks). This test was previously run in 2016, 2014, 2013, 2012, 2010, 2009 and 2006, as...

forum.dbpoweramp.com

It shows that those who ripped CDs without paying attention may have ended up losing 9% of their accuracy?
Those who say, "you will not notice." Please forward to me (or @amirm) 9% of your money. Yes, maybe "you will not notice" that either, but it would be appreciated.

Perhaps the offending CD ROM drives have an issue with laser, clock, circ implementation, ide or sata implementation, or who knows.

This does prove that optical disc data extraction is fallible. Why lose 9% accuracy if you don't have to?

The CDPro2 was discontinued in 2013, of course. But Philips has a track record of not supporting their older models. Some manufacturers like Theta and PS Audio were pissed, because they had no way to service the Philips-based transports like the Data Basic and the Lambda.