Transport quality revisited... what about jitter?

QUOTE (Mark B @ July 17, 2009 01:23 pm)

My point was that in the tests where a difference in sound quality was noticed, the transports being used for the test differed substantially in quality. Everything else being equal, any difference in sound quality could be attributed to the difference in quality between the transports.

In a test in which 2 medicre transports were used the expected result would be that little if any difference in sound quality existed between them. Similarly, if 2 superb transports were used for the test, the expected result would be little or no difference in sound quality. In either of these scenarios, it would be misleading to conclude that the lack of difference was due to transports having no affect on sound quality.

To properly test whether transports affect the sound quality, the transports used for testing must have a significant difference in quality between them.

OK, I see your point. However I tested with a Cyberhome CH-DVD 300 (MSRP $50) and a Marantz DV6001 (MSRP $500). The Marantz was selected by a UK magazine as the best DVD player under GBP500. While the Cyberhome player might be a sleeper, I would be surprised if it was anywhere near the quality of the Marantz. I plan to do some more direct A/B testing, but my initial impression was that there was no audible difference with these two when feeding my PS Audio Ultralink Two DAC.

NOTE: I also have the Marantz DV7001 (MSRP $800), which is a very substantial piece of equipment, but I have not tested it as a transport for my DAC.

Some more focused testing is definitely in order. Too bad no one has a jitter analyzer to help investigate the technical reasons behind what we may or may not hear.

Rob

QUOTE (rroobbcc @ July 17, 2009 03:20 pm)

QUOTE (Mark B @ July 17, 2009 01:23 pm)

My point was that in the tests where a difference in sound quality was noticed, the transports being used for the test differed substantially in quality. Everything else being equal, any difference in sound quality could be attributed to the difference in quality between the transports.

In a test in which 2 medicre transports were used the expected result would be that little if any difference in sound quality existed between them. Similarly, if 2 superb transports were used for the test, the expected result would be little or no difference in sound quality. In either of these scenarios, it would be misleading to conclude that the lack of difference was due to transports having no affect on sound quality.

To properly test whether transports affect the sound quality, the transports used for testing must have a significant difference in quality between them.

OK, I see your point. However I tested with a Cyberhome CH-DVD 300 (MSRP $50) and a Marantz DV6001 (MSRP $500). The Marantz was selected by a UK magazine as the best DVD player under GBP500. While the Cyberhome player might be a sleeper, I would be surprised if it was anywhere near the quality of the Marantz. I plan to do some more direct A/B testing, but my initial impression was that there was no audible difference with these two when feeding my PS Audio Ultralink Two DAC.

NOTE: I also have the Marantz DV7001 (MSRP $800), which is a very substantial piece of equipment, but I have not tested it as a transport for my DAC.

Some more focused testing is definitely in order. Too bad no one has a jitter analyzer to help investigate the technical reasons behind what we may or may not hear.

Rob

Are DVD players appropriate for testing this? My understanding is that unless a DVD player has a video bypass for Red Book CD output that the sound quality suffers.

QUOTE (Mark B @ July 17, 2009 04:10 pm)

QUOTE (rroobbcc @ July 17, 2009 03:20 pm)

QUOTE (Mark B @ July 17, 2009 01:23 pm)

My point was that in the tests where a difference in sound quality was noticed, the transports being used for the test differed substantially in quality. Everything else being equal, any difference in sound quality could be attributed to the difference in quality between the transports.

In a test in which 2 medicre transports were used the expected result would be that little if any difference in sound quality existed between them. Similarly, if 2 superb transports were used for the test, the expected result would be little or no difference in sound quality. In either of these scenarios, it would be misleading to conclude that the lack of difference was due to transports having no affect on sound quality.

To properly test whether transports affect the sound quality, the transports used for testing must have a significant difference in quality between them.

OK, I see your point. However I tested with a Cyberhome CH-DVD 300 (MSRP $50) and a Marantz DV6001 (MSRP $500). The Marantz was selected by a UK magazine as the best DVD player under GBP500. While the Cyberhome player might be a sleeper, I would be surprised if it was anywhere near the quality of the Marantz. I plan to do some more direct A/B testing, but my initial impression was that there was no audible difference with these two when feeding my PS Audio Ultralink Two DAC.

NOTE: I also have the Marantz DV7001 (MSRP $800), which is a very substantial piece of equipment, but I have not tested it as a transport for my DAC.

Some more focused testing is definitely in order. Too bad no one has a jitter analyzer to help investigate the technical reasons behind what we may or may not hear.

Rob

Are DVD players appropriate for testing this? My understanding is that unless a DVD player has a video bypass for Red Book CD output that the sound quality suffers.

I am not sure what you mean by a "video bypass", but the Marantz players a "audio" mode which shuts off all of the video circuitry. However, I understood this to be of only benefit the analog cicuits, i.e. when using the internal DACs of the DVD players.

QUOTE (clint e. @ July 16, 2009 07:43 pm)

.....
From the Blu-ray site: "A blue-violet laser (405nm) has a shorter wavelength than a red laser (650nm); this makes it possible to focus the laser with even greater accuracy..."

Also, i'd made some cd ripping using DBpoweramp - i don't find any differences between this software and EAC - and i thing on many rippings the cd-r have a better sonics than the original cd...
But, i am not surprised that CDs burned with a Blue Laser ,sound better than those burned with the much larger wavelength RED laser in normal CD/DVD burners, and the resulting higher precision of the pits and lands, but I wonder what all this has to do with Commercial CDs which are stamped from a glass Master. Surely modern CDs aren't created from an initial burn using a Red Laser,then a glass master made ?

QUOTE (rroobbcc @ July 18, 2009 03:18 am)

QUOTE (Mark B @ July 17, 2009 04:10 pm)

QUOTE (rroobbcc @ July 17, 2009 03:20 pm)

QUOTE (Mark B @ July 17, 2009 01:23 pm)

My point was that in the tests where a difference in sound quality was noticed, the transports being used for the test differed substantially in quality. Everything else being equal, any difference in sound quality could be attributed to the difference in quality between the transports.

In a test in which 2 medicre transports were used the expected result would be that little if any difference in sound quality existed between them. Similarly, if 2 superb transports were used for the test, the expected result would be little or no difference in sound quality. In either of these scenarios, it would be misleading to conclude that the lack of difference was due to transports having no affect on sound quality.

To properly test whether transports affect the sound quality, the transports used for testing must have a significant difference in quality between them.

OK, I see your point. However I tested with a Cyberhome CH-DVD 300 (MSRP $50) and a Marantz DV6001 (MSRP $500). The Marantz was selected by a UK magazine as the best DVD player under GBP500. While the Cyberhome player might be a sleeper, I would be surprised if it was anywhere near the quality of the Marantz. I plan to do some more direct A/B testing, but my initial impression was that there was no audible difference with these two when feeding my PS Audio Ultralink Two DAC.

NOTE: I also have the Marantz DV7001 (MSRP $800), which is a very substantial piece of equipment, but I have not tested it as a transport for my DAC.

Some more focused testing is definitely in order. Too bad no one has a jitter analyzer to help investigate the technical reasons behind what we may or may not hear.

Rob

Are DVD players appropriate for testing this? My understanding is that unless a DVD player has a video bypass for Red Book CD output that the sound quality suffers.

I am not sure what you mean by a "video bypass", but the Marantz players a "audio" mode which shuts off all of the video circuitry. However, I understood this to be of only benefit the analog cicuits, i.e. when using the internal DACs of the DVD players.

Yes, when I said "video bypass" that was meant to be synonymous with the "audio" mode which shuts off the video circuitry. Really, was that not clear to you?

Perhaps dingus would weigh in here regarding whether the sound quality is not as good when using a DVD to play a CD through an external DAC without the "audio" mode being engaged? Yeah or nay?

QUOTE (Mark B @ July 18, 2009 02:19 pm)

...Perhaps dingus would weigh in here regarding whether the sound quality is not as good when using a DVD to play a CD through an external DAC without the "audio" mode being engaged? Yeah or nay?

i can only speak for the Kenwood as it is the only dvd player i've used for redbook cd playback... it was not a good performer in this regard, very thin and almost completely lacking in the low end. used with the EAD dac it did make for a very nice transport though. as for its audio mode, if i ever used it the experience was not noteworthy as i have no recollection of doing so.

I can borrow a Proceed PDP3 from Echo Audio in Portland. I googled it and can't find any specs regarding how low the jitter is in the digital receiver, or the jitter attenuation frequency.

Since Rob thinks that these are the key factors in determining whether different quality transports will sound the same through an external DAC I don't know if the Proceed will qualify for testing. Getting these specs for DAC's doesn't appear to be very straightforward.

QUOTE (Mark B @ July 18, 2009 01:19 pm)

Yes, when I said "video bypass" that was meant to be synonymous with the "audio" mode which shuts off the video circuitry. Really, was that not clear to you?

Mark, to be honest a bit back a few of your posts started to have a combative tone, as does the way you asked "Really, was that not clear to you?" I am not sure why this is, but to avoid any misunderstanding that would further feed that tone, I wanted to be clear that we were talking about the same thing. Apparently my search for clarity was offensive. If I said anything else that offended you somewhere in this thread, then I apologize. user posted image

Rob

QUOTE (rroobbcc @ July 18, 2009 05:15 pm)

QUOTE (Mark B @ July 18, 2009 01:19 pm)

Yes, when I said "video bypass" that was meant to be synonymous with the "audio" mode which shuts off the video circuitry. Really, was that not clear to you?

Mark, to be honest a bit back a few of your posts started to have a combative tone, as does the way you asked "Really, was that not clear to you?" I am not sure why this is, but to avoid any misunderstanding that would further feed that tone, I wanted to be clear that we were talking about the same thing. Apparently my search for clarity was offensive. If I said anything else that offended you somewhere in this thread, then I apologize. user posted image

Rob

Combative? I was annoyed by your last post questioning the meaning of "video bypass". Come on, be honest -- the meaning was crystal clear.

Rob, if you read my posts and your responses, virtually every one of your responses claims to not understand what I mean.

Then you state

QUOTE

a bit back a few of your posts started to have a combative tone

Every post of mine that you are calling combative were questioning your conclusions and testing methodology, which I felt was justified.

QUOTE (clint e. @ July 15, 2009 02:47 pm)

Of course.
IMHO, one of the most important differences between an average cdp and a great cdp lies into the power supply design.
Any leakage current (interference) between the servo mechanism controlling the speed of the spinning disc and the crystal oscillator controlling the output of the buffer may unstabilize the crystal oscillator enough to add jitter to the clock signal. As a matter of fact this is one of the reasons i moved to computer as a source.

The hard drive uses an asynchronous interface - SCSI. The disc is always spinning at the same high speed and the heads land on the spot you need when the data is requested. The data coming out is completely unclocked (it comes out in bursts) and has to pass through the SCSI barrier into a buffer located in a different chassis than the hard disc (the computer)... thus, there is great distance between the varying currents of the spinning disc motor and the oscillator driving the output of the buffer in the computer chassis. Since the computer power supply only has to power the output oscillator, the result imo can be much more stable. Same for a cdp or transport... there are "audiophile cd players" where great attention has been made to power supply design, and these players exhibit much less jitter and better sound.

Clint e., I read the following in a Stereophile review of the Genesis Digital Time Lens and I thought it probably relates to your experiences using a computer as a transport...

Let's say you play a CD on a poor-quality CD transport and store the digital audio data in a massive computer memory. You then repeat the process, but this time play the CD into the memory from the finest CD transport extant (say, the Mark Levinson No.31). A week later you feed the two sets of data from the massive memory into a digital processor and listen to the music. Would the CD transports' sonic signatures be removed from the signal? Could you hear a difference between the transports a week later?

I believe that the two reproductions would sound identical. Because the memory's output clock bears absolutely no relationship to the transport's clock, the sound would take on the characteristics of the memory's output clocking circuitry. Any jitter in the transport and the digital cable driving the memory would be completely removed from the digital audio signal. [I have performed a similar experiment, storing the datastreams from nominally identical but different-sounding discs on a large computer hard-drive. When the two sets of data are played back from the hard drive, they now sound the same.—Ed.]

That's the theory behind the new Digital Lens from Genesis Technologies. Designed by Paul McGowan, the Digital Lens uses not an hour's worth of memory, but a few seconds—long enough to isolate your digital processor from any jitter or speed inconsistencies in your transport and let you listen to CDs in real-time. This is why Genesis Technologies calls the Digital Lens a jitter eliminator rather than a jitter-reduction device.

Rob

QUOTE (rroobbcc @ July 18, 2009 07:12 pm)

... the Digital Lens uses not an hour's worth of memory, but a few seconds—long enough to isolate your digital processor from any jitter or speed inconsistencies in your transport and let you listen to CDs in real-time. This is why Genesis Technologies calls the Digital Lens a jitter eliminator rather than a jitter-reduction device.

a neat idea, but did you catch footnote #2?

...The AD1890's output is jitter-free, but the sample amplitudes can be slightly different from what is required. The part takes in the right samples at the wrong time, and outputs the wrong samples at the right time. [The difference, however, is specified by Analog Devices as being below the 16-bit noise floor.—Ed.] Ironically, the error introduced by this process is conceptually identical to the error introduced by jitter.

QUOTE (dingus @ July 18, 2009 09:28 pm)

QUOTE (rroobbcc @ July 18, 2009 07:12 pm)

... the Digital Lens uses not an hour's worth of memory, but a few seconds—long enough to isolate your digital processor from any jitter or speed inconsistencies in your transport and let you listen to CDs in real-time. This is why Genesis Technologies calls the Digital Lens a jitter eliminator rather than a jitter-reduction device.

a neat idea, but did you catch footnote #2?

...The AD1890's output is jitter-free, but the sample amplitudes can be slightly different from what is required. The part takes in the right samples at the wrong time, and outputs the wrong samples at the right time. [The difference, however, is specified by Analog Devices as being below the 16-bit noise floor.—Ed.] Ironically, the error introduced by this process is conceptually identical to the error introduced by jitter.

Yep. On top of that I am sure that the Genesis device + cable to the DAC has its own intrinsic jitter. So at the end of the day I would expect it to only be a real benefit if the transport + cable in question had MORE jitter than the Genesis box. There is review I once read about the Theta (or it might have been the Audio Alchemy) jitter reducer, which said basically the same thing.

QUOTE (rroobbcc @ July 19, 2009 02:12 am)

QUOTE (clint e. @ July 15, 2009 02:47 pm)

Of course.
IMHO, one of the most important differences between an average cdp and a great cdp lies into the power supply design.
Any leakage current (interference) between the servo mechanism controlling the speed of the spinning disc and the crystal oscillator controlling the output of the buffer may unstabilize the crystal oscillator enough to add jitter to the clock signal. As a matter of fact this is one of the reasons i moved to computer as a source.

The hard drive uses an asynchronous interface - SCSI. The disc is always spinning at the same high speed and the heads land on the spot you need when the data is requested. The data coming out is completely unclocked (it comes out in bursts) and has to pass through the SCSI barrier into a buffer located in a different chassis than the hard disc (the computer)... thus, there is great distance between the varying currents of the spinning disc motor and the oscillator driving the output of the buffer in the computer chassis. Since the computer power supply only has to power the output oscillator, the result imo can be much more stable. Same for a cdp or transport... there are "audiophile cd players" where great attention has been made to power supply design, and these players exhibit much less jitter and better sound.

Clint e., I read the following in a Stereophile review of the Genesis Digital Time Lens and I thought it probably relates to your experiences using a computer as a transport...

[i]Let's say you play a CD on a poor-quality CD transport and store the digital audio data in a massive computer memory. You then repeat the process, but this time play the CD into the memory from the finest CD transport extant (say, the Mark Levinson No.31). A week later you feed the two sets of data from the massive memory into a digital processor and listen to the music. Would the CD transports' sonic signatures be removed from the signal? Could you hear a difference between the transports a week later?

I believe that the two reproductions would sound identical. Because the memory's output clock bears absolutely no relationship to the transport's clock, the sound would take on the characteristics of the memory's output clocking circuitry. Any jitter in the transport and the digital cable driving the memory would be completely removed from the digital audio signal. [I have performed a similar experiment, storing the datastreams from nominally identical but different-sounding discs on a large computer hard-drive. When the two sets of data are played back from the hard drive, they now sound the same.—Ed.]
..........

Rob

Tanx Rob, that's exactly what i 'm saying, because Jitter is NEVER transferred with the data to a new medium, if a clock is not involved. And SCSI does not involve a clock. Jitter is strictly an interface phenomenon, whenever a clock is involved.

Another interesting and more modern - the Genesis Digital Time Lens was made in 96 - proposal to build a CD player based on a SCSI mechanism comes from the pro-audio guys from Alesis:

http://www.stereophile.com/cdplayers/605/

QUOTE (rroobbcc @ July 19, 2009 11:24 am)

QUOTE (dingus @ July 18, 2009 09:28 pm)

QUOTE (rroobbcc @ July 18, 2009 07:12 pm)

... the Digital Lens uses not an hour's worth of memory, but a few seconds—long enough to isolate your digital processor from any jitter or speed inconsistencies in your transport and let you listen to CDs in real-time. This is why Genesis Technologies calls the Digital Lens a jitter eliminator rather than a jitter-reduction device.

a neat idea, but did you catch footnote #2?

...The AD1890's output is jitter-free, but the sample amplitudes can be slightly different from what is required. The part takes in the right samples at the wrong time, and outputs the wrong samples at the right time. [The difference, however, is specified by Analog Devices as being below the 16-bit noise floor.—Ed.] Ironically, the error introduced by this process is conceptually identical to the error introduced by jitter.

Yep. On top of that I am sure that the Genesis device + cable to the DAC has its own intrinsic jitter. So at the end of the day I would expect it to only be a real benefit if the transport + cable in question had MORE jitter than the Genesis box. There is review I once read about the Theta (or it might have been the Audio Alchemy) jitter reducer, which said basically the same thing.

Even tough, look at the measurements from 1996 :

http://www.stereophile.com/digitalprocessors/824/index9.html

...and, please remember that the measured intrinsic jitter of a DAT reproducer is greater than 100 times the jitter of a good CD transport which is on the order of 10 to 100 picoseconds.