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Old 8th July 2006, 10:14 PM   #1
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Default D-Clock it.....................

This thread is intended for discussions about the new D-Clock.

If you have any questions ... please bring'em on

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Old 9th July 2006, 02:27 AM   #2
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Default Re: D-Clock it.....................

Quote:
Originally posted by Lars Clausen
This thread is intended for discussions about the new D-Clock.

If you have any questions ... please bring'em on

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I like the transformer isolated OP and integrated reg, very good
idea. This should provide much more consistent results across a
wider range of retrofit situations.

Question WRT transformer OP, since it swings +- about gnd
terminal do you need a 1/2 supply reference on other side of
coupling cap?

Is transformer part of filter circuit?

What type of oscillator is it?

Do you have phase noise graph. Plenty of commercial clocks
acheive 1.5ps, but i think low phase noise close to carrier freq is
important and difficult to get.

Cheers

Terry
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Old 9th July 2006, 08:24 AM   #3
chaise is offline chaise  Taiwan
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As a user of LC Audio XO3, I am very insteresting in D-clock.

Since the spec both look the same from web(exclude the price... ), I wonder if D-clock can beat XO3 a lot or.....
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Old 9th July 2006, 08:38 AM   #4
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Terry: Thanks for your questions ....
Your CD circuit already has the 1/2 VCC circuit, so no need to worry about that.
The transformer is not part of a filter circuit, it transmits fully to the other side.
It's a Collpitts oscillator.
At this point i don't have noise graphs, so the jitter level is only calculated from the potential noise sources in the signal chain.
However much of the benefit of a clock comes from the fact that it is totally decoupled from the signal modulated noise of the CD player. The question however is always, how good is it decoupled?

Best regards

Lars C
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Old 9th July 2006, 12:31 PM   #5
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Quote:
Originally posted by Lars Clausen
Terry: Thanks for your questions ....
Your CD circuit already has the 1/2 VCC circuit, so no need to worry about that.
The transformer is not part of a filter circuit, it transmits fully to the other side.
It's a Collpitts oscillator.
At this point i don't have noise graphs, so the jitter level is only calculated from the potential noise sources in the signal chain.
However much of the benefit of a clock comes from the fact that it is totally decoupled from the signal modulated noise of the CD player. The question however is always, how good is it decoupled?

Best regards

Lars C
Lars,

Thanks for answers.

Yes, I did assume you had very high PS rejection from CD supply.

Cheers

Terry
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Old 9th July 2006, 12:39 PM   #6
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1 Hz from 9 to 24V that comes to some 0,003 ppm/V of PSR.
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Old 10th July 2006, 03:18 AM   #7
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Quote:
Originally posted by Lars Clausen
1 Hz from 9 to 24V that comes to some 0,003 ppm/V of PSR.
Lars,

I have heard from a friend, Joe Rasmussen, that even way below
1Hz is a benefit. I usually go a factor of 10 (0.1Hz) just to be
safe but I can't say for sure it is a definitive improvement (as Joe
did).

I am using shunt regs on XO currently but have found the actual
XO topology more important than the PS.

0.003ppm = 170dB PSRR. That is a whole lot - do you care to
disclose anything about the PS?

Thanks,

Terry
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Old 10th July 2006, 07:52 AM   #8
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Terry: Of course

It consist first of a dual HF filter with Q damped chokes. They work from 2 MHz up. Then there is the holding caps, and in the beginning of the regulator a two stage pre regulator for ripple removal.
After that a constant current source and a LM329DZ low noise reference. I found that one to be the lowest noise of any reference on the market. This way it doesn't have to be post filtered very much.
Later the 3V / 5V regulators, and post filtering with OSCON's.

I hope this description is fulfilling.

Best regards

Lars Clausen
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Old 16th July 2006, 06:40 AM   #9
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Quote:
Originally posted by Terry Demol


Lars,

I have heard from a friend, Joe Rasmussen, that even way below
1Hz is a benefit. I usually go a factor of 10 (0.1Hz) just to be
safe but I can't say for sure it is a definitive improvement (as Joe
did).

I am using shunt regs on XO currently but have found the actual
XO topology more important than the PS.

0.003ppm = 170dB PSRR. That is a whole lot - do you care to
disclose anything about the PS?

Thanks,

Terry
170dB is the "0 Hz" rejection, at higher frequencies 170 dB is something to dream about only :-)
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Old 16th July 2006, 06:41 AM   #10
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Quote:
Originally posted by Lars Clausen

At this point i don't have noise graphs, so the jitter level is only calculated from the potential noise sources in the signal chain.Best regards

Lars C [/B]

Hi Lars

What is the low frequency corner you included in your calculations ?

best
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