OK. And insulation... from what - variations? You seem to know a lot about the subject. What tests and findings have you done? How did you change the temperature? How did you measure close in noise ("offset")? What was the sound impressions?
How do one do the isolation?
Please share.
//
How do one do the isolation?
Please share.
//
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Airflow, moving air cause small temperature variations which in turn cause low frequency phase noise Xtal should be protected against it.
Attached is a phase noise measurement of 2 used commercial OCXO. Differences are only at low frequency under 20Hz. The sound quality difference between them is easily noticed. To my hears one was better, at that time I didn't have the phase measurement setup so I write "bad sounding" on it and forget it until I can measure phase noise. And measurements agreed with listening!
You will find some explanation about measurement setup here : The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
I can't say about the sound quality of the Laptech xtal oscillator, measurements are not finished. Looks like this clock is better than the actual, if the sound quality improves I know I will never be able to put it back to finish measurements! So I wait...
Joël
Attachments
Hi Joël,
very nice results! seems Laptech crystals are good stuff!
It could be very interesting if you would share your Wenzel based measurement system (hardware & software).
I believe there are many members interested on an affordable phase noise measurement system, me too.
I started a thread about phase noise measurement
Building a phase noise measurement system for digital audio
Ill be very glad if you would share your experience in the above thread.
Thanks
Andrea
Notice about available parts
Please see:
http://www.diyaudio.com/forums/group-buys/291925-tempered-master-clock-buy-24.html#post5339563
Please see:
http://www.diyaudio.com/forums/group-buys/291925-tempered-master-clock-buy-24.html#post5339563
Hi, Andrea,
Please check your mail.
Also, do you have any suitable circuit for differential oscillators? Thanks.
Still wondering maybe it is better to hold SC-cut oscillators in separate box due to potential heat issue.
WYAN
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Not sure what you mean by differential oscillator. Possibly this?: http://leapsecond.com/museum/sul25-1/
Standard practice is to have the active components in with the crystal so they have the same thermal stability. Its less of an issue with this application but long wires at 11, 22,44 Mhz or higher frequencies have a lot of negative impacts including the series inductance and the RF radiation.
Standard practice is to have the active components in with the crystal so they have the same thermal stability. Its less of an issue with this application but long wires at 11, 22,44 Mhz or higher frequencies have a lot of negative impacts including the series inductance and the RF radiation.
Hi,
Thanks. There are some differential circuit like in this lecture note:
http://rfic.eecs.berkeley.edu/~niknejad/ee142_fa05lects/pdf/lect23.pdf
I am more concerned if it is a good idea to host sc-cut crystal oscillators in the same box as other components due to heats. Especially dual sc-cut. Thermal stability is another issue that needs to be taken care of whether oscillators are in a separate box.
Cheers.
WYAN
Thanks. There are some differential circuit like in this lecture note:
http://rfic.eecs.berkeley.edu/~niknejad/ee142_fa05lects/pdf/lect23.pdf
I am more concerned if it is a good idea to host sc-cut crystal oscillators in the same box as other components due to heats. Especially dual sc-cut. Thermal stability is another issue that needs to be taken care of whether oscillators are in a separate box.
Cheers.
WYAN
Hi Andrea,
I have some optimisations and simplifications to do and then I will post schematics. Please be patient!
Joël
From AT-Clapp to SC-Driscoll
Hello Andrea,
This is an update to post #1240.
The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
Time for a feedback! A few days ago I finally managed to get the SC-cut Driscoll 22/24 working. No issues to that whatsoever. I wanted to wait a few days while keeping on listening, because I did not trust my ears, but my listening impressions were confirmed day after day....
From the sonic footprint of my AT-cut Clapp 45/49 I already was so much pleased that I did not expect a huge gain in performance. Yes, I was hoping for an improvement, but this is close to unbelievable.
Soundstage, positioning of instruments, voices, all so live and dynamic...
Thank You, Thank You, Thank You, Andrea !!!
Having made that experience there is no question that I am also interested in that HC-47/U SC-Cut 3rd overtone 5.6448.
The Well Tempered Master Clock - Group buy (Post #248)
It is not possible to go lower than 22/24 MHz to reach 176.4 / 192 kHz. But there are so many 44.1 kHz CD's that might profit of the furthermore lower phase noise / jitter (lower frequency plus better Q).
The GB for the 47/U SC-cut 5.6448 MHz and 6.144 MHz might not reach MOQ, so I can only encourage you to jump on that train and let Andrea develop that clocks too.
Regards,
Hans
Hello Andrea,
This is an update to post #1240.
The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
Time for a feedback! A few days ago I finally managed to get the SC-cut Driscoll 22/24 working. No issues to that whatsoever. I wanted to wait a few days while keeping on listening, because I did not trust my ears, but my listening impressions were confirmed day after day....
From the sonic footprint of my AT-cut Clapp 45/49 I already was so much pleased that I did not expect a huge gain in performance. Yes, I was hoping for an improvement, but this is close to unbelievable.
Soundstage, positioning of instruments, voices, all so live and dynamic...
Thank You, Thank You, Thank You, Andrea !!!
Having made that experience there is no question that I am also interested in that HC-47/U SC-Cut 3rd overtone 5.6448.
The Well Tempered Master Clock - Group buy (Post #248)
It is not possible to go lower than 22/24 MHz to reach 176.4 / 192 kHz. But there are so many 44.1 kHz CD's that might profit of the furthermore lower phase noise / jitter (lower frequency plus better Q).
The GB for the 47/U SC-cut 5.6448 MHz and 6.144 MHz might not reach MOQ, so I can only encourage you to jump on that train and let Andrea develop that clocks too.
Regards,
Hans
Attachments
... Thanks for sharing your experiences ... I really sense enthusiasm in your wording You could take the 5.4 MHz source and either multiply it (Low Phase Noise Systems – Hints and Tips |) or phase lock a 22 MHz or 44 MHz oscillator. Since its an even ratio the circuit becomes much simpler and should be free of any spurii.
Hi Hans,
nice job!
I'm very glad you have got such that improvement with SC crystals.
I had the same sonic impressions when I installed the 11.2896 SC-cut oscillator in a TDA1541A DAC: very wide soundstage, crystal clear treble but never harsh, voices so realistic.
About 5/6 SC-cut crystals... stay tuned, my discrete DAC is in progress (although it will take long time). It will work up to 192 kHz (or maybe 384 kHz) with such low frequency master clock.
Note for all DAC users: Sigma-Delta aside, the most important signal in digital to analog conversion is the Word Select (the latch signal), not the bit clock (used to load DAC registers). So if your favourite DAC can be driven separately (asyncronous bit clock to load DAC registers, stopped bit clock, synchronous latch directly from the master clock) you could get great improvement driving the Word Select at lower frequencies because at 5/6 MHz you can get crystals with the highest Q as possible, that typically means lower phase noise/jitter.
Andrea
Great thread!
Does anyone have experience in transformer isolation of the clock circuit?
The SMD isolator is not overly expensive
See
NewClassD Neutrino 24.00
Does anyone have experience in transformer isolation of the clock circuit?
The SMD isolator is not overly expensive
See
NewClassD Neutrino 24.00
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