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Jitter graphs, AudioMaster comments - 1/13/2003 2:29:03 PM   
Pio2001

 

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Very interesting work,

The graphs scaling looks special, for example page 2, second graph, the Yamaha 4x is 24 ns. The blue bar of the Plexwriter 0+ is more than twice as big. Therefore we could expect the jitter to be about 50 ns, but it is only 27.39.

We can see that Plextor Varirec is optimised at 0, that is exactly what was expected ("Plextor says that the default setting already reflects the optimized laser power with the lowest jitter").

Yamaha's AudioMaster burns at 1.2 m/s instead of 1.4 m/s. Thus the jitter is expected to be modified by a ratio equal to
1.2/1.4=0.86

The ratio measured are

Ritek
4x pit 0.95
4x land 0.86

Tayo Yuden
4x pit 0.77
4x land 0.82

1x pit 1.08
1x land 1.00

8x pit 0.83
8x land 0.80

That is sometimes more, sometimes less.

Sorting the normal mode data on burning speed, we get

Ritek pit-land jitter
4x 24-29 ns
48x 30-32 ns

Tayo Yuden pit-land jitter
1x 26-30
4x 27-32
8x 30-30

With audio Master :

Ritek pit-land jitter
4x 23-25 ns
8x 25-27 ns

Tayo Yuden pit-land jitter
1x 28-30 ns
4x 21-26 ns
8x 25-24 ns

To my eyes, there is no correlation between the media used (Ritek or TY), the burning speed (from 1 to 48x) and the jitter.
Only Audio Master, at 4 or 8x (not at 1x) seems to have a positive effect on jitter.
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RE: Jitter graphs, AudioMaster comments - 1/13/2003 3:02:03 PM   
john

 

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Thanks for your comments about the scale of the graphs, we may need to change the scale of all graphs to be the same...

To make safe assumptions we must perform more tests, and of course Jitter will change according to the used media.

I think the most interesting was that most 48X/52X writers will not produce good results at the maximum writing speed...


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RE: Jitter graphs, AudioMaster comments - 1/24/2003 11:44:38 AM   
PaulVG

 

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One small correction to the original post: Audio master quality records at 1.4 m/s instead of 1.2 m/s. Since AMQ writes 'larger', it is easier for the reader to read. That's also why the recording length of a CD is reduced by a factor (1.4/1.2): 74minutes x (1.2 m/s) / (1.4 m/s) = 63 minutes.

A request for new tests: Use a "CD-R Audio (for consumer)": these disks are optimised for recording speeds between 1x and 8x. I'm curious to know if the jitter is even lower with AMQ on those disks.

And finally, to answer the most important question: does it sound better? YES. You will notice the difference if you have a good Hifi system, you will not hear the difference while driving your car or while jogging with your walkman.

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RE: Jitter graphs, AudioMaster comments - 1/24/2003 8:02:04 PM   
john

 

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>Use a "CD-R Audio (for consumer)"

Hmm...Yes it may show some different results. We will examine this.




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Post #: 4
RE: Jitter graphs, AudioMaster comments - 1/25/2003 11:58:56 AM   
Clint


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quote:
Originally posted by PaulVG

And finally, to answer the most important question: does it sound better? YES. You will notice the difference if you have a good Hifi system, you will not hear the difference while driving your car or while jogging with your walkman.



Yamaha themselves suggest otherwise...

They proclaim that the difference is best noted in low-end CD players as their level of ECC is poorer compared to quality Hi-Fi components, whose ECC can correct large amounts of resulting jitter occuring when coupled with low quality media/burners (or recorded at 48X+ speeds).





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Post #: 5
RE: Jitter graphs, AudioMaster comments - 1/26/2003 8:48:56 PM   
Pio2001

 

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I tested the SPDIF output of an old Yamaha CDX860 CD player (1991, 450 ), whatever digital cable used (cheap coax, 75 Ohm coax, optical), no errors in the output : bit for bit identical to the ripped wav file. Checked with a pressed CD, and a 24x burned CDR without audio master (4 minute track). No difference is audible between the original and the copy in the analog output (Arcam Diva A85 stereo amplifier (1200 ), Dynaudio Gemini speakers (1000 - 1500 audiophile kit), Senheiser HD600 headphones (300 ).


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Post #: 6
RE: Jitter graphs, AudioMaster comments - 1/27/2003 6:49:24 PM   
Halcyon

 

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Pio,

of course you know that bit-perfect output isn't the same as difference not being audible.

The jitter inherent in the media may not be totally removed from the bit-stream even if it's buffered?

Why? Because many devices use cheap VCO's instead of stable crystals and draw the clock from the incoming data.

This means that the data may also be jittery when output (of course it will have transport jitter, because no output is clear from jitter, regardless of how well the buffer is done).

And this jitter will be more audible on audio gear that has bad jitter immunity at D/A stage when played back.

This is all theory of course, but solid at that.

regards,
Halcyon


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Post #: 7
RE: Jitter graphs, AudioMaster comments - 1/28/2003 2:16:20 AM   
Pio2001

 

Posts: 18
Joined: 6/27/2002
From: France
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quote:
Originally posted by Halcyon

of course you know that bit-perfect output isn't the same as difference not being audible.


I know that difference not being audible doesn't mean bit perfect (there can be inaudible errors).

I don't know if bit perfect means difference not being audible on >150$ soundcards or >250$ CD Players. I think so, and tend to push people for ABX results. Just one ABX result showing an audible difference would be extremely valuable, but so far... none.

I don't say my results proves that bit perfect means audibly perfect, they don't. They are just an example of result, that I think to be rather common, although objective data about this subject is very rare : no ABX tests (even from Bob Katz, http://www.digido.com), no bit for bit comparisons (oh, yes, Bob Katz did ).


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RE: Jitter graphs, AudioMaster comments - 1/28/2003 2:20:56 AM   
Pio2001

 

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Oops ! Big omission in the post above : I meant that I didn't know if bit perfect meant audibly perfect with the same DAC, that is, talking about the sound of digital outputs, not analog.


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Pio2001

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Post #: 9
RE: Jitter graphs, AudioMaster comments - 1/30/2003 10:50:40 AM   
PaulVG

 

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quote:
Originally posted by Clint

quote:
Originally posted by PaulVG

And finally, to answer the most important question: does it sound better? YES. You will notice the difference if you have a good Hifi system, you will not hear the difference while driving your car or while jogging with your walkman.


Yamaha themselves suggest otherwise...
They proclaim that the difference is best noted in low-end CD players as their level of ECC is poorer compared to quality Hi-Fi components, whose ECC can correct large amounts of resulting jitter occuring when coupled with low quality media/burners (or recorded at 48X+ speeds).



What I should have added to make my statement clearer: with AMQ you hear less noise in the signal, the sound is clearer. When listening to music in an environment with a lot of noise (street, car), you will not hear that.

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Post #: 10
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