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The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
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Old 20th April 2019, 03:41 PM   #1741
wlowes is offline wlowes  Canada
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Old 21st April 2019, 12:17 AM   #1742
andrea_mori is offline andrea_mori  Italy
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Default Boards 3D model

Since a member asks for boards 3D model I publish 3D PDF document for each boards mentioned in this thread.
TWTMC-C.PDF

TWTMC-D.pdf

TWTMC-DIL.PDF

TWTMC-OVN.PDF

TWTMC-P.pdf

TWRPS-pp micro.PDF
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Old 15th June 2019, 09:36 PM   #1743
mr_whocares is offline mr_whocares  Germany
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Default one oven, two XOs

Hi Andrea,

Do you see any issues using just one oven for two clocks ? I was thinking to double the length of the copper tube, solder it in the middle and insert the XOs from both sides.

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Old 17th June 2019, 12:00 AM   #1744
1audio is offline 1audio  United States
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The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
In an ideal world you would test each crystal for its "turnover" temp, the temperature at which its most stable and then adjust the heater to match usually within +/- .1C or whatever you can manage. In that case each crystal will be a little different.

I don't think that's possible with this type of oven and you aren't chasing frequency perfection, just stability, low drift and low phase noise so probably no real sacrifice to share an oven.
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Old 17th June 2019, 01:22 AM   #1745
gerhard is offline gerhard  Germany
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Quote:
Originally Posted by 1audio View Post
In an ideal world you would test each crystal for its "turnover" temp, the temperature at which its most stable and then adjust the heater to match usually within +/- .1C or whatever you can manage. In that case each crystal will be a little different.
That's what they do in commercial double crystal ovens:

< http://www.karlquist.com/oven.pdf >

He talks about crystal temperature stability of +- 100 uK (Mikro-Kelvin).

You don't know the exact inflection point of your crystals, just
that ist's somewhere near 70C or whatever you have ordered, and you
have no realistic means to measure it.

But that's not really bad. The simple oven will allow your crystal to
operate close to the sweet spot. Remember other crystals have to work
without any temp stabilization. I would not hesitate to put 2 crystals
into the same oven, as long as they are designed for the same temperature.

Just make sure that they cannot see each other electrically.

regards, Gerhard
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Old 17th June 2019, 07:45 AM   #1746
mr_whocares is offline mr_whocares  Germany
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Many thanks for your replies, gentlemen!

The crystals are sitting tightly in the copper tube, so their housings will be connected electrically together. Is that an issue? Do I have to try to find away to isolate the housings from each other?

Regarding the temperature setting points, I do not have the exact measurement data from the manufacturer and which working temperatures are recommended for my crystals. (Maybe Andrea could help on that topic if he still has the manufacturer data). What I did was to choose the temperature of 82C mentioned in the Andreas's document as the starting point and then fine adjusted it just by hearing! The sound changes are audible within few centigrade ( 3C ?), so I hope that the recommended temperatures for the two crystals are within few centigrade too. :-)

what is your experiences for adjusting the temperature of the oven ? Do you hear changes in sound quality , let's say, for +/- 1C?

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Old 17th June 2019, 09:00 AM   #1747
wealas is offline wealas
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I thought the temp listed on the crystal case was supposed to be the inflection point temp?
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Old 17th June 2019, 11:10 AM   #1748
gerhard is offline gerhard  Germany
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Oh, if they are marked, use it
If you have several of them, how big is the spread?
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Old 17th June 2019, 11:43 AM   #1749
wealas is offline wealas
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I'm not home at the moment but Andrea posted the shipping docs and they do contain the temps. Here is the list from the latest batch: The Well Tempered Master Clock - Group buy
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Old 17th June 2019, 01:10 PM   #1750
diyiggy is offline diyiggy
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Greetings,

I please have some questions, I think I missunderstood several things.

Does the temperature of the dac cabinet can change the temperature targett of the ovens?
I think I easily have around 35c inside the cabinet ...
What about the distance between an oscillator/sc cut crystal with a masterclockboard (ianfifo in my setup)? If there are for example 4 inches, will it add jitter? If yes is it that important for a 16/44 or 20/96 old pcm dac chip ?

Is there a problem of frequency or stability of it with extra jitter due to the distance?
Does it affect phase noise which seems from the few I believe to understand is what we want at low frequencies below 10 htz vs cchd-957 or NDK crystals?

Many questions sorry, I get the 5 Mhz sc cut from Andrea and I would like to know the best layout trade off I should targett but some basics I already understood as the wire impedance between boards.
Many thanks if you can enlight me,
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