|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
In Reply to: I posted this question to you at the digital board last month posted by jeromelang on May 02, 2003 at 09:54:02:
Jerome,Ron posted:
"Can you detail this procedure? I can capture the 1394 bitstream
(but only for unencrypted 44.1/16 PCM) and test to see if the same
bits are delivered for each iteration. If I showed you the bitstream
was exactly the same each time, would you continue to hear this
phenomenon?"Do you detect the repeat difference with CD material over iLink? If so, Ron can cap the bitstreams. If the bitstreams are the same, what do you think could be going on? More importantly WHERE could this difference be coming from?
Very interesting...
Follow Ups:
I have been trying CDs much of yesterday, and I can certainly confirm that the same problem is audible with CDs as well. I have also tried some DVDs movies and noted that the same problem is happening too. Although I must say that the degree of difference noted in the Pioneer combi playing CDs is less than what I observed through the SCD-1/BAT VK-20/Pass Lab X-350 combi. I used the same SS-M7 speakers for the test. This is not to say that the Pioneer has "minimised" the problem. I think it is because the Pioneer VSX-A10i amplifier is less revealing and transparent. I also confirm this point yesterday afternoon, when I compared the Pass Lab X-1 pre-amp to a Goldmund pre-amp model that has been touted locally as being "faster" and more "dynamicially-alive" by the dealer, which I interpret as better in transient response. No dice. The problem can be heard in the Pass more evidently than the Goldmund. The CD player being used incidentally, was also a Goldmund, which also have this problem. In this regard, I consider the Goldmund pre-amp, while offering a more "attractive audiophile sound", to be less neutral and transparent than the Pass, and certainly the Pass allows me the hear the problem more clearly.Some CDs that I tried that are more audible than others:
Jennifer Warnes - Famous Blue Rain Coat (track 3, 7)
Dire Straits - Brothers in Arms XRCD (track 4,6,9)
Eagles - Hell Freezes Over XRCD (track 10)
Jose Careras - Misa Criolla (track 2,3,4)
Creedance Clearwater Rivival CD layer on Hybrid SACD - Cosmo Factory (track 5,6,7,9,10)In all these cases, take note of the shift in soundstage, which in every case, became more recessed into the back of the speakers. They also image better and sound more opened. Many instruments that have complex harmonic structures like Piano, Saxophone, multi-layered guitar effects and Synth are very much affected by the jitter problem and they usually sound harsher and harmoncally muddier as a result of the multiple layers being messed up in time. Vocals mixed with dense reverbs or recorded in a very reverberent venue are also very much affected.
Just one specific example:In the opening intro of Dire Strait's "Your Latest Trick" and J.W.'s "Famous Blue Raincoat", you can hear the position of the sax will shift backwards and is clean from reverb smudging when the track is repeated. You can hear many other similar examples on the tracks that I listed above.
But even that pales in comparison to what can be improved in the "musicality" aspect. Through this procedure, you begin to hear a kind of effortless ease, a sense of continuousness to the way the music flow that is in abundance so far found only with vinyl playback. Clearly, there more's to it than the "bits is bits" claim.
Hope the good Doctor can investigate this problem without prejudice.
Thanx for posting your 44.1/16 PCM results. I'll bring my DV-47Ai
to work and use the Jennifer Warnes disc as the test material.
Here's my test plan.1) capture track 3 from 1394. Right now, I'm just using an
8 megabyte memory buffer, which is 47 seconds. This will be the
reference bitstream.2) capture track 3 from 1394, but hit track repeat after 10 seconds.
Compare first 10 seconds with reference bitstream. Compare second
37 seconds with reference bitstream.3) capture track 3 from 1394, but hit track repeat after 20 seconds.
Compare first 20 seconds and second 27 seconds with reference.4) capture track 3 from 1394, but hit track repeat every 10 seconds.
Compare 1st, 2nd, 3rd and 4th 10 second segments and last 7 second
segment with reference.Acceptable? Any additional tests you would like performed?
You seem to imply that if the data (1's and 0's) appear to be the same in all these tests, then one will hear no difference? How do you intend to measure the differences in timing of each sample?Anway, please also include data bitstream captured from track 3 without track-repeat and played continously from track 2. The reason for this is because the instances where most jitter are generated are observed at the beginning of the track when it continues from a preceeding track. Hence, I always have to stop play, select track by number keys and then hit the SKIP Backward keys. Pressing SKIP BACKWARD keys more than once will negate the sonic improvement. You don't have to perform test 4 where you repeat every 10 secs. The 12th second spot seems to give the best results. Be sure to remove additional AC tweaks to your monitoring amps and speakers.
If you wish for these correspondences to remain confidential, pls e-mail me directly from now. Thanks for taking this up. Pls see explanation from Ole Lund Christiansen for possible reason that this is happening.
> You seem to imply that if the data (1's and 0's) appear to be the
> same in all these tests, then one will hear no difference? How do
> you intend to measure the differences in timing of each sample?I can only capture the 1394 bitstream. I do not have the VSX-49TXi
receiver to measure the sample jitter at the DAC.To base all conclusions on my proposed test, we must have faith
that the receiver is properly buffering and reclocking the stream.
Pioneer claims "zero jitter", and if they are using a halfway
decent crystal oscillator, it seems very attainable to me.
Charles Hanson has suggested that the clock routing to the
DAC may not be optimul, but I've seen no measurements that
would indicate the clock signal is not clean and jitter-free.However, my proposed test would certainly confirm or deny Ole Lund
Christensen's speculations on a mechanical reason for the
phenomenon.BTW, I couldn't find the Jennifer Warnes disc at my local CD
emporium. CD layer of CCR Cosmo Factory is much easier to find.
I'll pick it up tomorrow.
Hope you will be able to get to the bottom of this problem and come up with a solution. Who knows, this might turn out to be the most impactful and profound development in the progress of digital audio.
This post is made possible by the generous support of people like you and our sponsors: