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[USER]

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[jae]

Smallest footprint CD setup I can think of theoretically is using something like an external USB DVD/Bluray drive connected to some kind of small device like a Raspberry Pi, which your dac is connected to directly with USB, bit perfect and low jitter. Could probably even replace the Raspberry Pi with something like an android phone/tablet depending on software/drive compatibility. There are also a lot of compact DVD/Bluray players with coax out that can be had cheaply and can plug right into your dac.

 

[Wes]

No evidence suggests that CD players used as transports will sound different from each other, nor are there engineering reasons to suspect they might.

But why not rip them to a HDD/SSD on your computer? Smaller footprint and you save $500 - not to mention the convenience.

 

[Wes]

I'm gonna say no to your question. Choose the prettiest or easiest to use transport.

OTOH, I don't think anyone has ever done a double blind, matched level listening test on CD transports...

so if you want to toss a buncha $$ and time at that -->

 

[Doodski]

It's just with Cambridge touting the "servo" in the CXC, I was wondering if there were differences that mattered between transports.

All CD players have servos. They operate at all times enabling the tracking of the disc and are there by the standard of the design agreed upon between Sony and Philips. Some do it better than others but if the data stream coming off the disc is "pure" then the DA should not have a different data stream.

 

[renaudrenaud]

During 90 we measured a lot of spdif output and it was a shame and sometimes a miracle the DAC can lock. Some companies cheat the spdif introducing some components to have a "signature". Other companies like CEC on their expansive cd players used to use bad clock so not all DACs were able to lock. There was a lot of jitter, back clocks and weak signal or .5V instead of full 2V.

Today USB solve these problems. I do not know the market of cd player today but for me it's a pure waste of money in technical point of view. Rip your files, use a NAS and read with a Raspberry.
https://sites.google.com/site/tvcaudiodocuments/home/spdif-hall-of-fame

 

[Standing in the rain]

I have the cxc transport and it works very well. I use it nearly every day without any problems. Feeding a very good dac you will be very impressed. I use it with a chord quest connected optically. It’s about as good as it gets, if cds are your thing.

 

[Zek]

Use Pioneer DV-300 (DV-393, DV-610 or similar) as CD transport with small improvement
http://lampizator.eu/LAMPIZATOR/REFERENCES/Goldmund/goldmundizator.html

 

[Chrispy]

I do have a lot of them as flac files on a hard drive. But this is a fairly large CD collection I amassed while working at a record store in my 20s. I treat it as a personal archive/historical record (like I do with my actual records kept upstairs). Call me sentimental...

But this all sounds great. It's just with Cambridge touting the "servo" in the CXC, I was wondering if there were differences that mattered between transports.

I'd just make that have all of your cd's as flac files. Coronatine time seems somewhat ideal for catching up. I keep my cd's but listen to them off various drives rather than the disc itself. The discs I tend to play are the hard to rip ones, multich SACD, DVD, Blurays.....and always use my disc players as transports only.

 

[Angsty]

I’m one of those people who still prefers spinning CDs to pushing FLAC files. I still own vinyl records, too!

How can CD transport performance be measured and compared?

 

[Wes]

see if the input to the DAC is bit perfect

 

[Vini darko]

I suppose the only meaningful difference in preformace would jitter from clock preformace or lack of. A badly engineered circuit might have noise issues, they'd have to be serious to affect the output.

 

[Angsty]

How can CD transport performance be measured and compared?

I did some digging around and found that there is an old standard, IEC 1096-1992, which provides guidelines. However, for a transport, I think only the section regarding the handling of CD defects would have much bearing.

https://www.sis.se/api/document/preview/120251/

 

[TimF]

I use a Denon DCD 50 cd player as a transport. It doesn't have optical so I use the coax connection. I also have a Pro-ject CD Box RS (not the RS2) Transport which I use, of course, as a transport. It would be interesting to compare the output of the two. I use them for convenience. I believe that playing music off a ripped cd file via a dedicated computer running J River by means of a USB connection to the DAC that there is no appreciable difference in sound than playing the cd itself via the Pro-ject CD Box RS connected to the DAC by optical or coax connections. For all appreciable, perceptible purposes they produce the same 'quality' sound. I cannot say that about comparing computer playback relative to the playback using the Denon DCD 50 since I have not done a comparison. I have prejudice and bias in this regard and I doubt that I could give the Denon DCD 50 an unbiased assessment. Regardless, I think that these days it is not necessary or wise to pay $2,000 to $3,000 for a cd transport. I think Audio Science Review has assessed and determined that cd based playback of well-ripped cd's is not just adequate but is equal to what you will get from the best cd transports. There simply isn't any reason to pay that kind of money. Instead get a nice computer and use it for playing your files. I do want to test this though: I want play a music cd on the internal Apple cd/dvd reader via outputting the stream to my external DAC (Topping D90) to see how that works, and also I want to attach an external dvd/cd reader/writer to my Apple computer and try steaming that music (data) to the DAC. I want to know if I can simply use the Apple computer as a transport for cd music as opposed to using either the Denon DCD 50, or the Pro-ject CD Box RS. I think $2,000 to $3,000 for unnecessary technology (these days) to read cd's is a bit much money. For a few hundred I'd say have the fun. That Pro-ject will have very poor resale value, I suspect. I am interested in others experience in this regard.

 

[restorer-john]

It is essentially a glorified computer CD drive with decent if unspectacular specs as a CD player. However, it has an optical out connection. So my question is, if I use the optical out to run it to a Topping E30, would it be reasonable to expect it to function as well as the CXC if used as a transport?

With discs in good condition, a CDROM based CD player will be relatively good for the job. With marginal discs, there is no comparison, they will be unable to retrieve or correct anywhere near as well as a standalone high quality CD player or dedicated high quality transport.

see if the input to the DAC is bit perfect

Bit perfect with what exactly?

If you cannot retrieve the data accurately in the first place due to various factors, and the error correction cannot fully correct, you have linear interpolation. Interpolated data looks no different and is no less valid to an external standalone D/A converter than corrected data, but result in everything from imperceptible to significant changes in the analogue output of the D/A converter.

 

[Angsty]

With marginal discs, there is no comparison, they will be unable to retrieve or correct anywhere near as well as a standalone high quality CD player or dedicated high quality transport.

Why? I’m trying to figure out how to measure the performance gain of a dedicated transport versus that of a mid-grade CD player with a coax digital output.

 

[restorer-john]

I think Audio Science Review has assessed and determined that cd based playback of well-ripped cd's is not just adequate but is equal to what you will get from the best cd transports. There simply isn't any reason to pay that kind of money. Instead get a nice computer and use it for playing your files.

I don't think ASR has done anything of the sort, please point me to any assessments of real time playback testing of a standalone CD player or transport as compared to either real time CDrom (computer) based playback?

 

[restorer-john]

Why? I’m trying to figure out how to measure the performance gain of a dedicated transport versus that of a mid-grade CD player with a coax digital output.

Inability to accurately reconstruct the original data. Marginal discs (and there are a huge amount of them) produce errors. The better the transport, the better the ability to correct, interpolate and provide the original (or close to it) data.

Without wanting to bore you, there are phenomenal differences in transports, CD players and computer based drives in that respect. Specially produced reference test discs are required to determine these differences. I own and use those reference discs not only for set up, alignment and performance testing, but for sorting out the best performing machines in my own collection.

 

[solderdude]

During 90 we measured a lot of spdif output and it was a shame and sometimes a miracle the DAC can lock. Some companies cheat the spdif introducing some components to have a "signature". Other companies like CEC on their expansive cd players used to use bad clock so not all DACs were able to lock. There was a lot of jitter, back clocks and weak signal or .5V instead of full 2V.
https://sites.google.com/site/tvcaudiodocuments/home/spdif-hall-of-fame

Yes, 20-30 years ago external DACs weren't anywhere near as good in locking to SPDIF signals and the signals that did come out of transports were 44.1/16 so DAC's didn't have to do much higher. Some could do 48kHz as well.
The used clock in CDP's wasn't much to write home about but wasn't poor either, perhaps with the occasional exception.
Disc speed ultimately was determined by the masterclock in the DAC part so at least the SPDIF would be fairly stable.
Jitter would be determined by the clock itself and the speed of the clock circuits used which is no problem inside the CDP itself.
Bandwidth limitations, cable imp matching, slew rate of of optical and electronic components as well as the locking capabilities of the external DAC determined how bad the jitter ended up when the internal CDP DAC was not used.
Not much jitter reduction and reclocking was done in external DACs.

An extrenal DAC would synchronize on the received SPDIF clock and often just jitter along or slightly reduce jitter with a slow PLL loop which had its own 'noise' and 'analog' issues.

This made it a hit or miss exercise in those days.

Today, most extrenal DACs have fairly decent jitter reduction, even on optical or electrical inputs. They may not be as good as USB though as different circuits and data formats are being transmitted and decoded. This we can see in many of the tests being done on ASR and elsewhere.
The 'jitter' is less of importance now as it was back in the day.

With a modern DAC and a decent transport (that reads all disc well) you'll be fine and need not to worry. When the transport has issues with discs (ticks, noise or other nasties) buy another one or when it is a really good one have it serviced (when possible).


This leaves me with @restorer-john 's remarks. He is totally correct of course. There are huge differences between drives in the way they handle tracking, focussing, TOC reading, skip speed, audible noise they make, longevity etc.
This means one can handle crappy discs 'better' than others, some may even play computer made CD's while others refuse to.
Not all CD's are created equal. Those that have actually serviced CDP's (I did) and got sent along problem CD's will have seen the substantial differences in eye patterns and weird 'skips' due to poor adjustment or spindle motor issues.
Certainly when there was a lot of smoking in the household the lenses would be dirty reducing signal.
C2 and CU errors were high leading to ticks or other noises sometimes.

So yes, there are differences between how well CD's are read (remember its a real time thing with no retries as PC CD readout works) and there are differences in SPDIF signal quality. The latter is 'receive side' dependent so stay away from vintage DACs and use a DAC that does well with SPDIF/Toslink jitter reduction and you should be fine.

Is there a difference in sound quality between them ? No... when there is you may have to look for a DAC with better jitter reduction.
The signal path and way incoming data is handled differs between SPDIF (optical/electrical) and USB.

 

[eliash]

With discs in good condition, a CDROM based CD player will be relatively good for the job. With marginal discs, there is no comparison, they will be unable to retrieve or correct anywhere near as well as a standalone high quality CD player or dedicated high quality transport.



Bit perfect with what exactly?

If you cannot retrieve the data accurately in the first place due to various factors, and the error correction cannot fully correct, you have linear interpolation. Interpolated data looks no different and is no less valid to an external standalone D/A converter than corrected data, but result in everything from imperceptible to significant changes in the analogue output of the D/A converter.

Just stumbling about this thread, therefore want to add my 5c to it and try to demystify some things.

Asked myself a similar Q whether to keep a nice transport (famous Teac VRDS-10 w. disc clamping, perfectly according to spec) and still use it with a new RME ADI-2 fs ADC/DAC.
Years ago, when starting with digital audio, I burned some CD-DA test discs, also incorporating a simple frequency sweep from 20Hz to 20KHz @-20db, as beeing usual to test analog equipment in the last millenium.
Interestingly, when listening with headphones, the was a faint beating noise noticeable in the middle of the already inaudible part.
First I though it was due to the old and not so well regarded DAC (and old digital filter) chips in that CD player (1st gen bitstream/sigma-delta TDA1547), so I hooked up a good Sabre ESS9018 reference design DAC via Toslink. Beating as well audible.
Thought it could be jitter on the Toslink.
Later, testing again with the new RME, with well regarded jitter supression on the Toslink input, same thing, beating noise audible.
So I thought it must be my self-burned test CD, since both DACs didn´t show any besting noise, when driven by PC(Netbook) and C-Media based USB to SPDIF/Toslink converter, with the same test signal, previously burned to CD-DA.
My ultimate test: An external CD-drive hooked up to the Netbook to test the test CD-DA showed no beating as well!

So my 5c: It could have been Sony´s CXD2500AQ front-end signal processor, providing the Toslink output and the internal DAC interface in the TEAC (not assuming any defect here!)...check that first, when looking for a perfect implementation...in case anybody knows, what is going on here, I am very interested!

Btw., sold the TEAC afterwards at a good price and incorporated a revised Philips CD-100 as a CD back-up (a gift from my father).
This one shows that beating as well...