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Old 30th December 2012, 02:42 PM   #31951
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fas42,
Could you go into a little depth on the differences between clocking in a CDP and clocking when using a hard drive based system? What I think I am reading is that as long as the data buffer is staying ahead of the clock frequency then the DA master clock will have no problems. As long as the hard drive information is stored as a loss-less file with identical bit for bit information then there should be no difference between the two types of storage media, CD or hard drive except where the master clock is located?

Forget this question I missed the last page of explanations.

Last edited by Kindhornman; 30th December 2012 at 02:54 PM.
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Old 30th December 2012, 02:52 PM   #31952
dimitri is offline dimitri  United States
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5,598,423 Very low jitter clock recovery from serial audio data
5,499,315 Adaptive digital audio interpolation system
5,404,362 Very low jitter clock recovery from serial audio data
5,388,221 Adaptive digital audio interpolation system
5,329,556 Reproduction equipment for digital audio
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Old 30th December 2012, 03:08 PM   #31953
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dimitri,
Are those patent numbers that you are sighting there?
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Old 30th December 2012, 03:14 PM   #31954
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Originally Posted by simon7000 View Post
Scott

This 1/f effect may very well translate into enough jitter to cause missed bits.
Nope, I don't know where you get this stuff. I'll give that 4 min. number to one of our telecom experts. A typical 10G com link settles to a 10^-12 error rate in usec. You throw out numbers like -120dB ripple in PLL filters, where's the reality check, I see nothing like that in the literature or the patents Dimitri listed?
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Last edited by scott wurcer; 30th December 2012 at 03:27 PM.
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Old 30th December 2012, 03:16 PM   #31955
dimitri is offline dimitri  United States
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yes, IN/Meitner
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Old 30th December 2012, 03:19 PM   #31956
Jakob2 is offline Jakob2  Germany
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Originally Posted by scott wurcer View Post
Thanks for this, my main concern is the design of the experiments. I didn't read every word but the above paper is interesting. The biwa is a good choice of instrument (the sibilance of a shakuhachi played by a master would also be interesting). One observation the mic has a large rising response past 20kHz and beyond that ripples that look a lot like those of a high order filter. With a strongly plucked instrument like the biwa, I would think it important to address the effects on the peak and shape of transients. I certainly am willing to entertain the possibility that the leading edge of transients can shift in localization. I definately have heard the sibilant sounds on instruments have an off image "noise" component added. OTOH I have perfectly enjoyable CD's and LP's of traditional Japanese instruments.

BTW - These instuments make sense as being right there in the room with you (as does solo acoustic guitar), I find almost any recorded examples to be so far from the reality I would probably look for something more fundamental wrong.
They tried at least to find out if the super tweeter reproducing the >20kHz content is offering a lot of IM distortion in the audio band.
They find around 25dB (SPL) when measuring the tweeter alone which translates to -55dB wrt ~80dB (SPL) .
They argued this IM in the audio band would be masked in any case what seems a bit too optimistic.
I don´t know the sound of these instruments as you do, and have never seen any spectral analysis of their sound, so the authors might be right.

I totally agree, quite often something fundamental is missing in existing recordings but the >20kHz thing might be useful in making a system better althought it can already work quite good without this extension in frequency range.

Btw, it was a bit surpising for me but i was not able to find measurments of microphone IM distortion at high frequencies and somewhat normal sound levels.
Holger Pastille´s PHD thesis is interesting (wrt to laser interferometer measurements of membran movement and the discussion about the various distortion mechanism at work) but concentrates on lower frequencies (up to 1kHz) and high sound levels.

Before you mentioned it, i would not have considered it as a serious problem, as harmonic distortion drops fast with lower sound levels.

@ kgrlee,

the Meyer & Moran experiment is unfortunately not an example of good scientific practice and it should not have passed the review board.

Nevertheless their results may be correct, but it is simply not possible to draw any conclusion about the reasons, due to lacking data and methodological flaws.

Last edited by Jakob2; 30th December 2012 at 03:23 PM.
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Old 30th December 2012, 03:30 PM   #31957
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Originally Posted by scott wurcer View Post
Nope, I don't know where you get this stuff. I'll give that 4 min. number to one of our telecom experts. A typical 10G com link settles to a 10^-12 error rate in usec.
Scott,

I think the problem is we are talking apples and bananas here. The question is who is which.

I'd be interested in knowing the error rate of the entire system. For 44,100 10e-12 would be a few times each year. 10e-7 looks like it would be enough to show up in music reproduction.

ES
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Old 30th December 2012, 03:44 PM   #31958
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Originally Posted by simon7000 View Post
Scott,

I think the problem is we are talking apples and bananas here. The question is who is which.

I'd be interested in knowing the error rate of the entire system. For 44,100 10e-12 would be a few times each year. 10e-7 looks like it would be enough to show up in music reproduction.

ES
Well you've got me confused again. The eye diagram on a typical audio link is orders of magnitude beyond that needed for even one dropped bit per cd.
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Old 30th December 2012, 03:53 PM   #31959
Waly is offline Waly  United Kingdom
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Originally Posted by Jakob2 View Post
the Meyer & Moran experiment is unfortunately not an example of good scientific practice and it should not have passed the review board.
Interesting, this would make the prof. at my university, using this paper in the Digital Processing course, blush. If you could substantiate your opinion (what was wrong in the paper and what would it take to correct the mistakes) I could feed him back, after the holidays.

EDIT: I am sure you are aware of this and this.

Last edited by Waly; 30th December 2012 at 04:06 PM.
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Old 30th December 2012, 03:56 PM   #31960
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Scott,
I know that the references that you are making are in the area of microphone distortion and IM above the 20Khz range but I think that this is also a very similar situation in the reproduction side of things with loudspeakers. If you have devices that are linear to above the 20Khz bandwidth without the hash that is present in most upper frequency devices I think that you would see a marked improvement in the reproduction of those sounds of instruments that have that type of upper frequency tonal qualities. Here is my take on that as regards loudspeakers. What we have to do is not only have the FR of the device in question have a bandwidth wide enough to reproduce those frequencies, but we also have to get the phase response correct. If you have a device that has a rising rate impedance and also has more than a purely resistive impedance curve you will never reproduce those frequencies correctly. Phase shifting is going to destroy those tones. We need to have a perfectly flat impedance curve, time coherent zero phase shift and flat frequency response. Only then can we produce those upper frequencies with any accuracy. It doesn't matter now good you get the electronic chain before the loudspeaker if you can't reproduce a coherent waveform from the loudspeakers, you are only chasing fairy dust then.
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