Universal 1ppm CD clock + SPDIF isolator low jitter

dublin78 · 25th April 2012, 02:56 PM

What does this do?
Where would it be wired into a CD player?
Universal 1ppm CD clock + SPDIF isolator low jitter ! | eBay

SoNic_real_one · 25th April 2012, 10:45 PM

Bull... That is a programmable gate array, it cannot reduce the SPDIF jitter.

Ken Newton · 26th April 2012, 02:58 AM

The Xilinx FPGA may contain internal RAM configured as a FIFO buffer, enabling the complete isolation of input clock jitter by creating new and independent clock domain for the circuits which follow. It hard to say for sure simply based on the minimal description given.

abraxalito · 26th April 2012, 03:16 AM

If it has a FIFO then it would need some kind of PLL but no sign of a VCXO on that board. There's only one osc, its not voltage controlled by the looks of it. I tend to agree with SoNic.

jitter · 05:35 AM

We have not been given a look at the bottom of correctly, there's no RAM. the pcb. Maybe there are components on that side too.

Edit: if I interpret the function block diagram of the XC9572XL corrcetly, it has no RAM.
I would take it for what the title says: SPDIF isolator (I presume galvanic isolation) and low jitter clock, but no jitter-killer.

abraxalito · 05:34 AM

Decoupling caps maybe. Osc module? - improbable, though of course not impossible

zinsula · 26th April 2012, 09:40 AM

1ppm....

I'm always suspicious when offerings claim low jitter but are wawing the long term stability (=ppm) of their clocks.

Audio needs low jitter, but doesn't care for frequency deviations in the long term.
Good long term stability doesn't imply low jitter.

Ken Newton · 03:00 PM

With a more careful reading of the function description, it appears that the board simply re-generates a cleaner S/PDIF waveform. To do this with only digital means they would need to time-slice the input S/PDIF signal, hence, I presume, the TCXO. In any case, I think it not justified for anyone to reflexively declare that the FPGA cannot play a role in jitter reduction. They can and they do form key parts of a DPLL, for example, in commercial DAC boxes. Even of the FPGA here is not being utililzed to create a DPLL.

chansiukwing · 27th April 2012, 07:45 AM

please visit here for more information: ( written in chinese only )
CD&CD-ROM×ªÅÌÍâ¹ÒÊ½¸ß¾«¶ÈÊ±ÖÓ°åVIISE - Create Dream

jitter · 27th April 2012, 08:36 PM

Unfortunately I don't read Chinese, but I'm guessing it's the same as the English text in the eBay advertisement.

Please tell us how jitter reduction is achieved.

25th April 2012, 02:56 PM	#1
dublin78 diyAudio Member Join Date: Mar 2006 Location: Cheshire	Universal 1ppm CD clock + SPDIF isolator low jitter What does this do? Where would it be wired into a CD player? Universal 1ppm CD clock + SPDIF isolator low jitter ! \| eBay __________________ Regards. Michael

26th April 2012, 02:58 AM	#3
Ken Newton diyAudio Member Join Date: Apr 2003 Location: Eastern Pennsylvania	The Xilinx FPGA may contain internal RAM configured as a FIFO buffer, enabling the complete isolation of input clock jitter by creating new and independent clock domain for the circuits which follow. It hard to say for sure simply based on the minimal description given. __________________ Ken

26th April 2012, 03:16 AM	#4
abraxalito diyAudio Member Join Date: Sep 2007 Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though... Blog Entries: 64	If it has a FIFO then it would need some kind of PLL but no sign of a VCXO on that board. There's only one osc, its not voltage controlled by the looks of it. I tend to agree with SoNic. __________________ When a measure becomes a target, it ceases to be a good measure. C.A.E. Goodhart

26th April 2012, 05:19 AM	#5
jitter diyAudio Member Join Date: Aug 2004 Location: Eindhoven, The Netherlands	We have not been given a look at the bottom of correctly, there's no RAM. the pcb. Maybe there are components on that side too. Edit: if I interpret the function block diagram of the XC9572XL corrcetly, it has no RAM. I would take it for what the title says: SPDIF isolator (I presume galvanic isolation) and low jitter clock, but no jitter-killer. Last edited by jitter; 26th April 2012 at 05:35 AM.

26th April 2012, 05:31 AM	#6
abraxalito diyAudio Member Join Date: Sep 2007 Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though... Blog Entries: 64	Decoupling caps maybe. Osc module? - improbable, though of course not impossible __________________ When a measure becomes a target, it ceases to be a good measure. C.A.E. Goodhart Last edited by abraxalito; 26th April 2012 at 05:34 AM.


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25th April 2012, 10:45 PM	#2
SoNic_real_one diyAudio Member Join Date: Jan 2008 Location: Virginia	Bull... That is a programmable gate array, it cannot reduce the SPDIF jitter.

26th April 2012, 09:40 AM	#7
zinsula diyAudio Member Join Date: Mar 2004	1ppm.... I'm always suspicious when offerings claim low jitter but are wawing the long term stability (=ppm) of their clocks. Audio needs low jitter, but doesn't care for frequency deviations in the long term. Good long term stability doesn't imply low jitter. __________________ If you can't trust your ears, then CLICK HERE

26th April 2012, 02:46 PM	#8
Ken Newton diyAudio Member Join Date: Apr 2003 Location: Eastern Pennsylvania	With a more careful reading of the function description, it appears that the board simply re-generates a cleaner S/PDIF waveform. To do this with only digital means they would need to time-slice the input S/PDIF signal, hence, I presume, the TCXO. In any case, I think it not justified for anyone to reflexively declare that the FPGA cannot play a role in jitter reduction. They can and they do form key parts of a DPLL, for example, in commercial DAC boxes. Even of the FPGA here is not being utililzed to create a DPLL. __________________ Ken Last edited by Ken Newton; 26th April 2012 at 03:00 PM.

27th April 2012, 07:45 AM	#9
chansiukwing diyAudio Member Join Date: Jul 2009	please visit here for more information: ( written in chinese only ) CD&CD-ROM×ªÅÌÍâ¹ÒÊ½¸ß¾«¶ÈÊ±ÖÓ°åVIISE - Create Dream

27th April 2012, 08:36 PM	#10
jitter diyAudio Member Join Date: Aug 2004 Location: Eindhoven, The Netherlands	Unfortunately I don't read Chinese, but I'm guessing it's the same as the English text in the eBay advertisement. Please tell us how jitter reduction is achieved.

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