External clock for DENON DCD1650SR - diyAudio
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Old 13th July 2004, 11:48 AM   #1
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Join Date: Dec 2003
Location: Sydney
Question External clock for DENON DCD1650SR

Hi All,

There must be some clever people out there who could suggest which clock to use, and how to feed a clock signal to both LC78625E AND DXP6001AF separately...

I know how to connect a clock signal to LC7865E no problem, remove two 15pF caps and connect external clock signal to pin 77. There's no resistor across pins 77 and 78.

I need suggestions on how to connect second, buffered signal, to DXP6001AF? Are there any external clocks that provide TWO clock-signal outputs? I am concerned about the inverter and timing. DXP6001AF (DENON's AL24 processor) generates 24 bit, 96kHz signal and feeds four PCM1704 DACs in dual differential mode. I do not think that LC78625E and DXP6001AF have to have clock signals in perfect sync. In other words, clock signal for DXP6001AF can lag a bit - it shouldn't mater. LC7825E generates 16MHz signal internaly, at pin 71.

I'm I right?

I should probably remove R194 and connect second buffered clock signal to C246. Can I remove inverter chip and connect clock signal straight to pin 42 of DXP6001AF chip, or this signal MUST be inverted?

Is there any danger in connecting AN ACTIVE external clock signals to these chips?

Your suggestions are highly appreciated!!!

Extreme_Boky
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Old 13th July 2004, 12:17 PM   #2
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Send a message via Yahoo to Elso Kwak
Hi,
Keep the buffer and feed the new clock to pin 77.
I bypassed the DAC and digital filter for the clock signal in my Philips CD931 as I am using the player as a transport and the difference in sound is pretty small.
Edit: But you can try your idea with my clock using the other output of the comparator too.
http://www.diyaudio.com/forums/showt...928#post199928
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Old 13th July 2004, 12:38 PM   #3
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Join Date: Dec 2003
Location: Sydney
Thanks Elso,

You probably meant I should keep the INVERTER......, right?

I like your clock7 a lot. Have you tried using o.1mF / 50V Black Gate NX for C3, C4, C8, C14 and C15? It is an APSOLUTE CHAMPION. However, it does not like any bypass caps - should be used on its own!

Can I obtain a clock7 PCB from you?

Regards,
Extreme_Boky
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Old 13th July 2004, 04:04 PM   #4
A 8 is offline A 8  Sweden
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Join Date: Mar 2003
Location: Gothenburg
I have another idea for you.

The PCM1704 have a great feature in that they trigger analog out based on the bitclock.
I would build or get a good clock, place it close to but shielded from the dacs, connect the clock directly to bitclock on the dacs and finally feed XIN on the sanyo chip from the same, new and improved clock.
To keep timing integrity you might need an inverter between the clock and XIN on the sanyo chip.

I have not done this on the chip combination you have but I have on others and it works very well, you basically make sure a good clock gets used where it matters the most.

If you show us how the 1704's get their bitclock and try to find out (there is typically a scope pic in the manual) which freq bitclock runs at then we can tell you if it is likely to work or not in your case.
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