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Old 1st October 2006, 08:22 PM   #31
Netlist is offline Netlist  Belgium
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Jan,
Thank you very much.

After further thinking - and having had a nice meal - the signal fed trough the whole chain as Mike did was only a 1Khz sine wave. Would the complexity of music still give the same results?
Because I think we (I only got the ball rolling) made a firm statement re. the complete digital audio world, more precise the cd player
Except for the jitter (pardon my ears but I still need to hear what jitter is at my age) there would be no difference between an average good cd player and a top high end model.
Do I miss something?

/Hugo
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Old 1st October 2006, 08:25 PM   #32
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Quote:
Originally posted by janneman

There will surely be burning or reading errors, often 1000's on a CD. The point is that the error correction correct all this 100% (unless uncorrectable errors cause error concealment but thats really rare these days). The fact that Hugo saw exact copies is a testimony how good the CD system is even with many, many errors occuring.
Would be interesting to see what effect burn and rip speeds have.

I'd say they will have zero effect but I know some single speed zealots will say it makes a difference.
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Old 1st October 2006, 08:32 PM   #33
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Indeed. Hugo, MikeB, what speeds did you guys use?

Jan Didden
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Old 1st October 2006, 08:33 PM   #34
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Quote:
Originally posted by Netlist
[snip]Do I miss something?

/Hugo

Itís that 92Khz noise in your ears that drives you mad.

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Old 1st October 2006, 08:48 PM   #35
Netlist is offline Netlist  Belgium
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Burn speed with Audition: 8X, can't go lower.
Rip speed with Audition: no idea, don't know if that can be made visible.
Rip speed with EAC: Slooooooooow.
CDR: Fuji Silver
Manufacturer ID: Ritek (97m15s17f)

/Hugo
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Old 2nd October 2006, 02:40 AM   #36
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If the data could not match up, the reast of the computer world is coing to be in trouble because all software are distributed by digital means.

I think the data will always match up once it gets digital, but when it gets burned, will the data location on the CD cause the player to read in a matter that will cause different modulation in the PSU is the main question, and probably the main cause of sounding different. Different burning speeds will cause different effects.

I do wonder what burning speed will be the best match most CD and DVD type players.
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Old 2nd October 2006, 10:03 AM   #37
MikeB is offline MikeB  Germany
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Quote:
Originally posted by janneman

Mike,

Didn't you just prove that S/PDIF jitter also has no effect?? S/PDIF in essence being an analog signal.

Jan Didden
Jan, SPDIF is a digital signal, only containing ones and zeros with varying length. The problem with jitter is, that the clock sync supplied with the spdif get's unaccurate, permanently beeing randomly a few nanoseconds too early or too late. If this clock is used to feed the DAC, you get some kind of FM-distortion. This causes ugly distortions for higher freqs, and these seem to be large enough to be audible.
My test only proved that no data gets lost when transfered via spdif. Jitter had no chance to take effect, it does not matter if data is received at uncorrect timings, when a spdif word was received, it will be dumped sequentially to harddisk/memory, loosing all jitter information.
In theory, reclocking the signal removes the jitter, but there are hot debates that this introduces new problems.

Hugo, the rmaa test signal also contains a part with complex noise, used for the freq response test. But, as the transfer is digital, the content of the digitized signal is quite unimportant.
You're right, an average good CD-player and a high end player will not make any difference for the data delivered. You can get differences with damaged CDs, depending on the error correction capability of the drive.

I've burnt the CD with 8x speed, the lowest speed my burner allows. Burning speed is relevant, and can be easily proved. Simply burn a DTS or DD encoded audio cd with 48x, and try to play that !
For DTS/DD any lost bit in the stream is a disaster, resulting in dropped audioframes (replaced with silence) or decoding errors giving very audible glitches.

About ripping speed, if the CD-drive/burner is of reasonable quality it seems to make no difference. I compared a track ripped at 1x and at 24x speed, no difference. Again, jitter can't take place here as only data is copied. I observed that if the drive gets into problems decoding the audiotrack, it does reduce rippingspeed by itself.

AFAIK, there are 3 problems with reproduction of digital sound:
- Quality of DAC
- Aliasing (because of too low samplerate)
- Jitter (Increased by bad/long spdif cable)

About the aliasing, it is visible with a scope. For example, play a 10khz sinewave through the CD-player and look at the signal with a scope. At first look, you see a nice sinewave (impressive regarding the fact that it was generated from ~4 samples !) If you look closer, you see some edges walking through the sinewave, even with 8x oversampling and brickwall outputfilter.
You'll need a good old analog CRO to see this.

There is one way out of jitter, it's a bidirectional digital connection (AES as i remember). The clock signal is generated by the dac and supplied by a 2nd cable back to the player. This way the player sends data "on demand", eliminating any jitter caused by cable/drive. The only jitter left is the accuracy of the clock from the dac.

Mike
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Old 2nd October 2006, 10:54 AM   #38
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Quote:
Originally posted by MikeB
Jan, SPDIF is a digital signal, only containing ones and zeros with varying length. [snip]My test only proved that no data gets lost when transfered via spdif. Jitter had no chance to take effect, it does not matter if data is received at uncorrect timings, when a spdif word was received, it will be dumped sequentially to harddisk/memory, loosing all jitter information.snipMike
Mike, I know that ...
I had the impression that using the S/PDIF you ran the data through a DAC-ADC combo.
I call S/PDIF an essentially analog signal since it is used that way: the zero crossings determine the period, while in a digital signal you would for instance count the pulses or the byte value or whatever. A bit tongue in cheek maybe, but some people call ANY signal essentially analog.

Quote:
Originally posted by MikeB
[snip]AFAIK, there are 3 problems with reproduction of digital sound:
- Quality of DAC
- Aliasing (because of too low samplerate)
- Jitter (Increased by bad/long spdif cable)

About the aliasing, it is visible with a scope. For example, play a 10khz sinewave through the CD-player and look at the signal with a scope. At first look, you see a nice sinewave (impressive regarding the fact that it was generated from ~4 samples !) If you look closer, you see some edges walking through the sinewave, even with 8x oversampling and brickwall outputfilter.
You'll need a good old analog CRO to see this.

There is one way out of jitter, it's a bidirectional digital connection (AES as i remember). The clock signal is generated by the dac and supplied by a 2nd cable back to the player. This way the player sends data "on demand", eliminating any jitter caused by cable/drive. The only jitter left is the accuracy of the clock from the dac.

Mike
Agree.

Jan Didden
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