CD Player/Transport Reviews

Jay's Audio CDT3-MK3 CD transport Measurements

Sidebar 3: Measurements

The most meaningful test of a CD player or transport is of how well it deals with disc errors. I examined the Jay's Audio CDT3-MK3's performance with the Pierre Verany Digital Test CD, which has tracks with single or double gaps in the data spiral. It successfully played tracks with gaps up to 1mm in length, but when the gap was 1.5mm or longer, there were audible glitches. The Compact Disc standard requires only that a player cope with gaps of up to 0.2mm. The Jay's transport copes well with damaged CDs.

Next, I examined the amount of timing uncertainty—jitter—in the CDT3-MK3's AES3 output by looking at the datastream's "eye pattern." I overlaid successive snapshots of the CDT3-MK3's AES3 output, taken over a 60s time window, with my Audio Precision SYS2722 system's digital oscilloscope function. The data, played back from a CD-R, represented the 16-bit Miller-Dunn J-Test signal, with the Jay's rear-panel switch set to a 44.1kHz output sample rate. With an ideal transmission system, all the pulse transitions in the datastream overlay one another to produce an image of a wide-open "eye" with just one trace visible.


Fig.1 Jay's Audio CDT3 Mk.3, eye pattern of AES3 data output carrying 16-bit, 44.1kHz J-Test data, no upsampling (±2V vertical scale, 175ns horizontal scale).

Fig.1 was plotted over one "unit cycle" from the AES3 output. The eye is superbly wide open, with no blurring of the leading or trailing edges; the pattern was equally good from the transport's coaxial S/PDIF output. The average jitter level, assessed with a 50Hz–100kHz bandwidth, was a low 389.2 picoseconds (ps).


Fig.2 Jay's Audio CDT3 Mk.3, eye pattern of AES3 data output carrying 16-bit, 44.1kHz J-Test data upsampled to 24 bits and 176.4kHz (±2V vertical scale, 175ns horizontal scale).

Fig.2 shows the eye pattern with the Jay's transport set to output upsampled 176.4kHz data. There is still no blurring. The average jitter level with 176.4kHz data was 535.1ps. Repeating this test with CD data representing a 1kHz tone at 0dBFS reduced the jitter with upsampled data to 437.8ps. Interestingly, while the Audio Precision's Digital I/O panel indicated that the expected 16 bits were active with 44.1kHz, all 24 bits in the AES3 stream were active when the data were upsampled to 176.4kHz.


Fig.3 Jay's Audio CDT3 Mk.3, digital-domain spectrum of pink noise at –20dBFS, upsampled to 176.4kHz, DC–50kHz (left channel blue, right red).

To confirm that the Jay's Audio CDT3-MK3's upsampling doesn't change audioband data extracted from CDs, fig.3 shows a wide-bandwidth spectral analysis of the pink noise track on Stereophile's Editor's Choice CD, analyzed in the digital domain, with no D/A conversion. The spectrum of the noise rolls off above 20kHz as expected, though it reaches full stopband attenuation at 24kHz rather than the expected 22.05kHz.


Fig.4 Jay's Audio CDT3 Mk.3, digital-domain waveform of undithered 1kHz sinewave at –90.31dBFS, 16-bit, 44.1kHz data upsampled to 176.4kHz (left channel blue, right red).


Fig.5 Jay's Audio CDT3 Mk.3, digital-domain waveform of undithered 1kHz sinewave at –90.31dBFS, 16-bit, 44.1kHz data (left channel blue, right red).

What I was not expecting was that while the Jay's Audio transport's upsampled output correctly reproduced the waveform of an undithered 1kHz tone at exactly –90.31dBFS analyzed in the digital domain (fig.4; the small amount of pre- and post-ringing on the waveform's leading edges will be due to the CDT3-MK3's upsampling filter), the 44.1kHz output behaved differently (fig.5). Here, the three DC voltage levels described by the data in fig.4 are overlaid with high-frequency noise. The direct and upsampled measurements were made from the AES3 output and confirmed via the S/PDIF output, which gave identical results.


Fig.6 Jay's Audio CDT3 Mk.3, digital-domain spectrum of 11.025kHz at –6dBFS, with LSB toggled at 229.6875Hz, sampled at 44.1kHz and upsampled to 176.4kHz (left channel blue, right red). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz.

It appears that the CDT3-MK3's 44.1kHz output adds dither at the level of the least-significant bit. I confirmed this by performing digital-domain spectral analyses of the transport's AES3 output while it played the Miller-Dunn J-Test track. With upsampled data (fig.6), the odd-order harmonics of the Fs/192 LSB-level squarewave all lie at the correct levels and there is no noisefloor between the harmonics.


Fig.7 Jay's Audio CDT3 Mk.3, digital-domain spectrum of 11.025kHz at –6dBFS, with LSB toggled at 229.6875Hz, sampled at 44.1kHz with no upsampling (left channel blue, right red). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz.

While the odd-order harmonics of the low-frequency squarewave are still at the correct level with the 44.1kHz output (fig.7), random noise is now present just below –130dBFS. (Remember that, as this spectrum was taken by analyzing the transport's digital output, there is no analog circuitry in the signal path that could add noise.) The level of this noise is typical of 16-bit, LSB-level dither.

I don't know what effect this dither will have on the performance of D/A processors that are connected to the Jay's CDT3-MK3, but it will limit the effective resolution of CDs played with the transport to closer to 15 bits rather than the 16 available on disc. By contrast, the upsampled output is bit-perfect with 16-bit CD data. Both types of output offer low jitter and well-resolved eye patterns, coupled with excellent error correction.—John Atkinson

COMPANY INFO
Jay’s Audio
33 Ubi Ave. 3
Singapore 408868
sales@beatechnik.com
65 8898 0911
jays-audio.com
ARTICLE CONTENTS

COMMENTS
Nyquist's picture
Submitted by Nyquist on May 5, 2023 - 10:20am

"To start with the most basic: Why does a CD player need to include error correction if there aren't any errors to correct? "

So you do not know? Seriously?

jimtavegia's picture
Submitted by jimtavegia on May 5, 2023 - 1:47pm

I understand the reason some spinners may sound better than others and why this improved when DACs started having RAM buffers and sending out the bits when needed. The idea of a very stable clock is important and why many use an external clock with more accuracy. I think a lot of this has gone away with the latest in DAC technology.

I always look at JA's jitter measurements as do most readers of Stereophile I would think. And with just this device, you still can't listen to anything.

To read the past reviews of what can be heard by some and not by others is always interesting. These differences can be traced to music listened to, the choice of speakers and electronics, the room, and the DAC used. This device coming from China with only a one-year warranty would be a deal breaker for me.

Mad Murray's picture
Submitted by Mad Murray on May 5, 2023 - 2:23pm

"To start with the most basic: Why does a CD player need to include error correction if there aren't any errors to correct? "

I am with @Nyquist on this and I am sure Mr. Reed and Mr. Solomon are also outraged.

If this is the qualty of reviewer that Stereophile employs its time they shut up shop

And who was the Editor that allowed this nonsense to get published.

Regards

Mad (as in crazy) Murray

MatthewT's picture
Submitted by MatthewT on May 5, 2023 - 2:49pm

It would save you some outrage in the future, and also keep you from looking like a moron.

Mad Murray's picture
Submitted by Mad Murray on May 5, 2023 - 3:02pm

its maybe more sarcastic than rhetorical.

Anyways, its all good fun whether its moronic or not.

And after resisting posting on this forum for maybe 20 years, I think I will retire on this high note.

Regards,

Mad (as in Moron) Murray

MatthewT's picture
Submitted by MatthewT on May 5, 2023 - 3:10pm

Without the emoticon. My apologies if appropriate.

Mad Murray's picture
Submitted by Mad Murray on May 5, 2023 - 3:22pm

but not sure about a /R for rhetorical.

Anyways we could both be wrong...maybe the author could clarify.

Regards,

Mad (as in Malcontent) Murray

Glotz's picture
Submitted by Glotz on May 8, 2023 - 9:17am

Well it's funny now!

jond's picture
Submitted by jond on May 5, 2023 - 3:39pm

Really guys? The no errors to detect was obviously a sarcastic potshot at perfect sound forever. I found Michael's review to be very well written and straight to the point well done sir!

Jason Victor Serinus's picture
Submitted by Jason Victor Serinus on May 5, 2023 - 6:33pm

My goodness. People got so upset that I went back to read the review. And there it is, plain as day

"But if there's one thing we've learned over 40 years of improving CD playback, it's that the format really isn't perfect at all. To start with the most basic: Why does a CD player need to include error correction if there aren't any errors to correct?"

Is it necessary to put some of these words in capital letters or bold (or both) in order for someone to understand what Alex is saying?

Everyone makes errors when they read something, especially when it's online and they're scrolling away. (That's where subscribing to the print magazine helps.) Nonetheless, given how many things in the world deserve our outrage right now, wouldn't it be best to read something twice before pulling the trigger and declaring, "If this is the qualty of reviewer that Stereophile employs its time they shut up shop. / And who was the Editor that allowed this nonsense to get published."

jason

Mad Murray's picture
Submitted by Mad Murray on May 5, 2023 - 11:31pm

I was yanking Stereophile's chain... obviously understanding sarcasm isnt your thing.

But I will conceded that the use of the term "outraged" and "editor" in combination is a British comedic construct so maybe thats why you missed it..noting I am not British.

Anyways been fun dipping my toes into your tepid pool.

Regards,

Mad (as in Mental) Murray

Mad Murray's picture
Submitted by Mad Murray on May 6, 2023 - 12:09am

..this is why I basically dont participate in online forums.

I am by breeding an extremely sarcastic person and as such its delivery generally gets lost in translation on the interwebs and sticking a "/s" on the end kinda defeats the purpose. People either get it or they dont.

Sayonara Dear Friend.

Mad Murray

Ortofan's picture
Submitted by Ortofan on May 5, 2023 - 8:58pm

... presented in the following video (starting at 18:00), the listening panel at Pearl Acoustics was unable to distinguish between a modern CD transport and the digital outputs of several CD players. The conclusion was that any audible differences between the group of digital players were solely attributable to the DAC section - the DAC chip itself and/or the following analog circuitry.

https://www.youtube.com/watch?v=TAOLGsS27R0

Jason Victor Serinus's picture
Submitted by Jason Victor Serinus on May 5, 2023 - 9:15pm

Both transport and DAC section matter. Do I want to debate? Are you kidding?

jason

Ortofan's picture
Submitted by Ortofan on May 5, 2023 - 9:46pm

... blind and with the output levels matched.
Do you do the same?

Bode's picture
Submitted by Bode on May 6, 2023 - 7:53pm

Jason. Why so sensitive. I think nyquist had a question. What did you mean. Maybe explain. And ya. Only DAC matters. If you have a different opinion then fine. But you are the professional. State your case.

Glotz's picture
Submitted by Glotz on May 8, 2023 - 9:19am

Further proof the internet sucks.

cognoscente's picture
Submitted by cognoscente on May 6, 2023 - 2:24am

The "eternal" debate among my audio buddies, does a CD sound (real and substantial) better than streaming? Or does a movie on a 4k blu-ray disc look (real and substantial) better than streaming. And if so, does it outweigh the inconvenience of a CD and DVD and ease of streaming? And then I'm not even talking about the difference in costs and the ability to stream (or buy and download as in my case) single tracks and making your own playlists instead of the obligation of buying an entire and fixed CD. I have a large CD collection as well as a DVD collection, I have certainly not played CDs for more than 5 years, DVD for almost 1 year. (I buy all my music in full uncompressed AIFF files and use my iPhone (which I already have) as storage, everything stored in the Onkyo HF Player app for Hi-Res output via a usb cable and that works just fine for me instead of a expensive Aurender of Silent Angel or whatever ssd-storage).

geoffrey vanhouwaert's picture
Submitted by geoffrey vanhouwaert on May 6, 2023 - 4:43am

hello,

English isn't even my native language but it was clearly a rhetorical question. Common guys.

best regards
Geoff

jimtavegia's picture
Submitted by jimtavegia on May 6, 2023 - 11:28am

I would love for him to take jitter measurements from a CD/DVD drive like the LG's we use USB in our two computers, my wife's and mine. I use mine for pulling in tracks off of CDs to look at them in my DAW. I would love to know from a affordable ($39) drive into a quality DAC what the worst case would be in jitter measurements? Certainly, measurable as anything else he does so well. Always curious.

In terms of this "CD reader" I am guessing one does an analysis as to what the market is lacking and works to design something that fits that niche. The other issue is statistical sampling when it comes to product quality...pulling every one, two, or three out of a 100 off the line and see if they work properly is not the right thing to do at this price point. Is there any burn-in time specified? This is where the customer becomes part of the QC department at a steep price.

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