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Old 11th March 2004, 12:16 PM   #1
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Default Slaving transport to DAC clock - with a wrinkle

Hi
I would like to implement a low-jitter clock in my DAC and slave my transport to the same clock
There seem to be two commercially available ways of doing this:
1. LCAudio - install a LClock XO 3 in the DAC (215 Euros). This has two clock outputs, one is used for the DAC, the other is taken by a user-installed co-ax lead to the transport and replaces the crystal in the transport
2. Guido Tent - XO-DAC with XO module in the DAC (267 euros), and a XO-3 with VCXO module in the transport (132 euros), with a link cable between the two. I don't really understand how this option works, but it does result in a free-running low-jitter clock in the DAC (ie not pulled about by a PLL anymore)

In any case, the whole thing is dependent on the transport and the DAC having the same clock frequency.
In my case, I have a Meridian 500 transport and an Audionote DAC kit 1.2, both are nominally 11.2896MHz

BUT....in this DAC, the 11.2896MHz clock is not actually used at all, instead a 2.8224MHz clock from the receiver chip is used to directly clock the DAC chip.
So in fact I would need a low-jitter 2.8224 clock in the DAC and a 11.2896MHz clock signal to send to the transport.

I do know that Guido's XO-DAC when fitted with a 11.2896MHz VCXO is capable of outputting the 2.8224 frequency, because this is what I used to use in my DAC until I blew the XO module up by being careless one day. I hope this is still possible with the XO module fitted, but I don't know.

Does anyone know whether the LCAudio LClock is also capable of outputting sub-multiples of the basic clock? (2.8224 = 11.2896/4)

Has anyone got experience of either of these two sync'ing methods?

Thanks

Maxwell
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Old 11th March 2004, 03:12 PM   #2
guido is offline guido  Netherlands
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Hi,

There is another recent post with all the info. I'm doing this for a 11.2896MHz CD player
too. In short: clock at DAC 11.2896 MHz with some dividers to get 2.8224MHz. And the
11.2896 is fed back to cd players decoder/filter. Inbetween you can put a fifo to avoid
timing problems, somebody did without however.

Use search on the word fifo.!

The other
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Old 11th March 2004, 04:13 PM   #3
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Default Re: Slaving transport to DAC clock - with a wrinkle

Quote:
Originally posted by Maxwell
BUT....in this DAC, the 11.2896MHz clock is not actually used at all, instead a 2.8224MHz clock from the receiver chip is used to directly clock the DAC chip.
So in fact I would need a low-jitter 2.8224 clock in the DAC and a 11.2896MHz clock signal to send to the transport.


Maxwell

The 11MHZ clock in the DAC1.2 is not a standalone clock. It is intimately tied to LRCLK and SDATA. For this to work properly you would have to generate SCLK (11.2896MHz) and LRCLK (44.1KHz)
and send them to the input receiver and dac chip with the PLL based clock in the transport.

ray.
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Old 12th March 2004, 05:38 AM   #4
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Guido
A search on fifo brings up 56 threads, and I'm afraid I can't work out which one you're referring to. Can you give me another clue?

I'm not an electrical engineer, I'm really wondering if either of the commercial sync-link options (LCAudio or Tent) will work with my DAC.
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Old 12th March 2004, 10:48 AM   #5
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Default Re: Re: Slaving transport to DAC clock - with a wrinkle

Quote:
Originally posted by rfbrw



The 11MHZ clock in the DAC1.2 is not a standalone clock. It is intimately tied to LRCLK and SDATA. For this to work properly you would have to generate SCLK (11.2896MHz) and LRCLK (44.1KHz)
and send them to the input receiver and dac chip with the PLL based clock in the transport.

ray.
That last line should have read
"send them to the input receiver and dac chip using a fixed clock in the DAC1.2 with the PLL based clock in the transport."

ray
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Old 12th March 2004, 10:56 AM   #6
guido is offline guido  Netherlands
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Quote:
Originally posted by Maxwell
Guido
A search on fifo brings up 56 threads, and I'm afraid I can't work out which one you're referring to. Can you give me another clue?

I'm not an electrical engineer, I'm really wondering if either of the commercial sync-link options (LCAudio or Tent) will work with my DAC.

Buffer choice for IIS Direct
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Old 12th March 2004, 09:40 PM   #7
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Thankyou Guido, I appreciate the trouble
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