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Old 1st January 2011, 02:54 AM   #21
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Quote:
Originally Posted by stephensank View Post
I can put in an enthusiastic vote for the Pioneer DV-656A(aka DV-45A). It's a HUGELY reliable laser & mech, and this generation of Pioneers, from 656A up to the DV-79avi(which has wonderful OPA2134A output opamps stock), are shockingly great sounding cd players even in stock form, and can be upgraded fairly easily to be even better.
unfortunately, from DV-46AV, DV600, etc. forward, Pioneer went to a MUCH LESS reliable laser maker. So, until I see that change, anyone asking me for a cheap but terrific cd player gets the strongest recommendation for the DV-45A & it's brothers. There is not a new dvd or even blu-ray player from any maker on the market that I could recommend, reliability-wise(which is as important to me as sound quality).
How old are those, 7-10 years? It seems that it was a burst of attention to DVD audio 10 years ago. And now, nobody is really interested.
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Old 1st January 2011, 03:56 AM   #22
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The DV656/45/59/79 are only about 5 years old at most. They are 'universal' players, meaning everything but blu-ray. SACD.DVD-A,DAD,CD, etc. And, frankly, age doesn't matter much on them, since they are the most reliable dvd players I've yet seen. Been using a DV-45A literally 24/7 in my shop for at least 2 years now, and not a single problem.
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Old 1st January 2011, 04:48 AM   #23
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Originally Posted by begemot61 View Post
What ADI DSP has to do with clock jitter? Clock jitter is a hardware related item. To have a good jitter, it is necessary to start with a good crystal itself, then it requires good and low noise front end (input buffer/comparator), and proper design of direct or indirect (PLL) clock architecture. ADI DSP is used for signal processing.
Are you real? When the signal is processed in ANY DSP with its OWN clock (therefore async to the input), the samples are reclocked with that clock. All the incoming jitter is GONE. Remains only the jitter of the XTAL of that DSP. Sure, some FIR magic and dual port memory are involved... but as jitter goes that's the fact.

Last edited by SoNic_real_one; 1st January 2011 at 04:53 AM.
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Old 1st January 2011, 07:27 AM   #24
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Hello

Most low and mid prices DVD players use noisy switch mode power supply, it's pollute all the circuits and worsen the jitter.

I have two mid prices DVD, one Toshiba and one JVC, my Adcom cd player sound way better than those DVD players. OPPO and Pioneer Elite DVD player are sounding good but cost much more. But I still prefer my Adcom cd player.

Bye

Gaetan
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Old 1st January 2011, 08:09 AM   #25
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Originally Posted by begemot61 View Post
What ADI DSP has to do with clock jitter? Clock jitter is a hardware related item. To have a good jitter, it is necessary to start with a good crystal itself, then it requires good and low noise front end (input buffer/comparator), and proper design of direct or indirect (PLL) clock architecture. ADI DSP is used for signal processing. It may use it's clock to do generate reference clock, but why it is better than just hardware based clock solution? DSP needs clock for it's internal operation. Quality of these clocks is not really very high.
Usually the DSP clock is the same as used to convert the data. In that case the jitter should be low.

But you are right, for signal processing, one does not need low jitter as such.

best
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Old 1st January 2011, 08:11 AM   #26
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Originally Posted by SoNic_real_one View Post
Are you real? When the signal is processed in ANY DSP with its OWN clock (therefore async to the input), the samples are reclocked with that clock. All the incoming jitter is GONE. Remains only the jitter of the XTAL of that DSP. Sure, some FIR magic and dual port memory are involved... but as jitter goes that's the fact.
So, what is the magic behind DSP clock and why it has better jitter than clock, generated anywhere else? And you have to sync your processing to the stream of data. Inside, DSP processing is async, all it has to do is to prepare the data before next sampling period. I can ask you the same question - Are you real? Or to be more exact, have you ever tried to design anything with DSP

Last edited by Eugene Dvoskin; 1st January 2011 at 08:23 AM.
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Old 1st January 2011, 08:18 AM   #27
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Originally Posted by begemot61 View Post
So, what is the magic behind DSP clock and why it has better jitter than clock, generated anywhere else?
You are right: No magic. Wrong implementation from Denon

The conversion clock should always sit close to the DAC, and be fed back to the DSP.

In addition, an oscillator on board with a million transistors switching on a DSP will never perform good in terms of jitter.......

happy new year !
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Old 1st January 2011, 04:01 PM   #28
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Originally Posted by begemot61 View Post
So, what is the magic behind DSP clock and why it has better jitter than clock, generated anywhere else?
The way it's working on any async DSP is simple -in all of them there is a buffer dual port or FIFO memory run by DMA, written with the incoming jittery signal and read with the stable XTAL clock. Much more stable than the jitter induced by an optical drive - CD or DVD.

And after that you have your FIR/upsampling/bass management DSP routines.

More: http://www.analog.com/static/importe...HRM_Rev4.0.pdf

Quote:
Shadow Write FIFO
Because the DSP’s internal memory must operate at high speeds, writes to the memory do not go directly into the internal memory. Instead, writes go to a two-deep FIFO called the shadow write FIFO.
When an internal memory write cycle occurs, the DSP loads the data in the FIFO from the previous write into memory, and the new data goes into the FIFO. This operation is transparent, because any reads of the last two locations written are intercepted and routed to the FIFO.
Because the ADSP-2191’s shadow write FIFO automatically pushes the write to internal memory as soon as the write does not compete with a read, this FIFO’s operation is completely transparent to programs, except in software reset/restart situations.

Last edited by SoNic_real_one; 1st January 2011 at 04:12 PM.
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Old 1st January 2011, 04:43 PM   #29
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Originally Posted by SoNic_real_one View Post
The way it's working on any async DSP is simple -in all of them there is a buffer dual port or FIFO memory run by DMA, written with the incoming jittery signal and read with the stable XTAL clock. Much more stable than the jitter induced by an optical drive - CD or DVD.
but not good enough for decent audio playback.....(the groundbounce of such chips is in the order of several 100mV - this voltage is in series with the clock signal since the clock relates to external ground.....)
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Old 1st January 2011, 06:09 PM   #30
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Quote:
Originally Posted by SoNic_real_one View Post
The way it's working on any async DSP is simple -in all of them there is a buffer dual port or FIFO memory run by DMA, written with the incoming jittery signal and read with the stable XTAL clock. Much more stable than the jitter induced by an optical drive - CD or DVD.

And after that you have your FIR/upsampling/bass management DSP routines.

More: http://www.analog.com/static/importe...HRM_Rev4.0.pdf
Sorry, I understand now what you meant. But the quality of the clock on DSP is comparable to the quality of the clock on SM8707HV, until some additional efforts are taken, starting with the quality of quarts crystal itself and the way, how generator is build. It may be possible to improve quality of both, by creating external generator. The other thing is FIFO. It is not ideal. You already have some jitter in the clock. FIFO is synced to this clock and while syncing, some jitter is added. It seems to be digital, but in reality it is all analog when it comes to jitter. The way how clock inputs are made should make big difference. It takes some time for the clock signal to switch it's state. During this time, any noise at the clock or at digital input will result in additional jitter.

In any event, they are on the order of magnitudes worse, compared to what Guido was describing. I'm not a big fun of audio extremism, it's just interesting how good is good enough. Guido's numbers surprised me a lot. Just wonder, how 1ps jitter was measured.
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