Some random AT-cut crystal plus a logic gate in a tin can does not need 3 days to reach thermal equilibrium with the environment. Any measured changes are academic.
Don't mixup measurement duration for testing at say 0,1 Hz and settling time for the osc!? These measurements can take many hours.
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The best sounding digital audio processing units (DAC's included) use oven-controlled cristal oscillators. MSB used to have the white papers on this topic available on their site, but not any more. The one such player that uses oven-controlled oscillators is Denafrips Terminator Plus.
Other manufacturers who care, use various isolation technics - some encapsulate the oscillators completely (Acusilicon) - but then an abient warm-up time is required to achieve the best sound. Some leave little corner holes (OPPO 205) that allows for an even, slow heat-up of the crystal used inside the encapsulation.
Other manufacturers who care, use various isolation technics - some encapsulate the oscillators completely (Acusilicon) - but then an abient warm-up time is required to achieve the best sound. Some leave little corner holes (OPPO 205) that allows for an even, slow heat-up of the crystal used inside the encapsulation.
Because that would be a waste of time....just think about it. Such oscillator would still need to be soldered to the PCB somehow - and that will transfer the heat.
The best approach is to oven-control the heat inside the oscillator, to provide an optimum temperature for the used crystal, that will, in turn, provide the lowest phase noise possible.
EDIT: Plus, the optimum temperature is usually achieved very quickly -> 10-15min and it is kept constant, irrelevant of the surrounding temperature (inside the player).
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That's common in applications that need absolute stability, but not audio. MSB is not a credible reference.
I thought the clock mongers that inhabited this forum years ago were anti-OCXO. I guess that's now a fad.
Thirty years ago when GSM was new one of the specs was that it had to be on frequency lock within 20 minutes from a -30C cold start. Whilst the whole networks back than were referenced back to an atomic reference (GPS clock sources were in their infancy still) it still needed an OXCO in the base stations. So for me, if something isn't stable with a few mins from a room temp start either the design is wrong or the parameter doesn't matter.
Hmm.. The 7GHz R&S FSV7 on my table does not switch off, it just goes into standby with the OCXO constantly on. Several of my old HP analyzers, too. The ones with high stability option does have the standby option usually. The Pendulum CNT-91 on the other table is going to standby, owen constantly on, too. I can look up quite more in the lab, shell I start?
Scopes are less frequently having it. They are also not relevant tools for close-in phase noise purposes. And yes I still like to use them for jitter analysis..
Ciao, George
Did you take it apart to verify that? I can find no mention of that nor required warm-up time beyond 30 minutes in the FSV7 manual. If it kept the OCXO on, you would think it would be noted in the manual, as the device may be on a shelf and not plugged into mains all the time. Again, it requires 30 minutes to reach spec. Not 3 days for some cheap AT cut audio XO.
Stability, not an issue for audio. This is a joke. You are another fetishist, yes I know. Audio is not metrology.
Flagship Keysight PNAs require 90 minutes for stability according to the datasheet. Keysight N5511A - 20 minutes.
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Maybe you should read the statement in the datasheet. All of them, including phase noise.
https://scdn.rohde-schwarz.com/ur/p...pdf_1/FSV_FL_dat-sw_en_3606-7982-22_v1300.pdf
BTW, that datasheet is for a different set of FSV models. The FSV7 manual itself does not even mention a warm up time at all!
https://scdn.rohde-schwarz.com/ur/p...sv_1/FSV_K73_3GPP_FDD_UE_UserManual_en_04.pdf
So, yes, when a Keysight N5511A, which starts at $135k USD and can measure phase noise down to -177 dBm/rtHz at room temperature according to the datasheet only requires 20 minutes of warm up time, I am going to call this BS out.
Keysight can apparently near theoretical limits in 20 minutes from cold with an OCXO. Don't worry about that though, you need to let your Crystek CCHD-957, which isn't even sealed, run for 3 days to allegedly HEAR the difference... lol
https://scdn.rohde-schwarz.com/ur/p...pdf_1/FSV_FL_dat-sw_en_3606-7982-22_v1300.pdf
BTW, that datasheet is for a different set of FSV models. The FSV7 manual itself does not even mention a warm up time at all!
https://scdn.rohde-schwarz.com/ur/p...sv_1/FSV_K73_3GPP_FDD_UE_UserManual_en_04.pdf
So, yes, when a Keysight N5511A, which starts at $135k USD and can measure phase noise down to -177 dBm/rtHz at room temperature according to the datasheet only requires 20 minutes of warm up time, I am going to call this BS out.
Keysight can apparently near theoretical limits in 20 minutes from cold with an OCXO. Don't worry about that though, you need to let your Crystek CCHD-957, which isn't even sealed, run for 3 days to allegedly HEAR the difference... lol
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Ok, thanks. I did look at the first pdf you posted.
Do you think its specs are suitable to measure the phase noise in digital audio reproduction equipment (DAC's)?
"... which starts at $135k USD and can measure phase noise down to -177 dBm/rtHz at room temperature according to the datasheet only requires 20 minutes of warm-up time" I see, and you believe that this is sufficiently good enough to capture the phase noise spectre at 0.01Hz?
Ok, I see that it does actually measure the phase noise starting from 0.01Hz.
Do you have any proof that its oscillators are actually powered off in stand by? Do you have any pictures of its internals that show the actual oscillators? If they do indeed get switched off completely, I would seriously consider the validity of the measured results.
Do you think its specs are suitable to measure the phase noise in digital audio reproduction equipment (DAC's)?
"... which starts at $135k USD and can measure phase noise down to -177 dBm/rtHz at room temperature according to the datasheet only requires 20 minutes of warm-up time" I see, and you believe that this is sufficiently good enough to capture the phase noise spectre at 0.01Hz?
Ok, I see that it does actually measure the phase noise starting from 0.01Hz.
Do you have any proof that its oscillators are actually powered off in stand by? Do you have any pictures of its internals that show the actual oscillators? If they do indeed get switched off completely, I would seriously consider the validity of the measured results.
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That's not its primary purpose, considering you have to buy a package to enable it.
You tell me, though:
https://scdn.rohde-schwarz.com/ur/p...df_1/FSV-K40_dat-sw_en_5213-9705-22_v0200.pdf
Maybe you should read the datasheet / manual yourself. Call Keysight and ask them if their $135k phase noise analyzer is good enough for audio clocks maybe while you're at it, lol.
You tell me, though:
https://scdn.rohde-schwarz.com/ur/p...df_1/FSV-K40_dat-sw_en_5213-9705-22_v0200.pdf
Maybe you should read the datasheet / manual yourself. Call Keysight and ask them if their $135k phase noise analyzer is good enough for audio clocks maybe while you're at it, lol.
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I read what you wrote perfectly fine, but I can't read your mind and can't pre-read what you edit in later.
The manual says it takes 20 minutes to warm up without any qualification. Feel free to contact them for clarification. I don't own one, but if I did, I wouldn't take apart a calibrated piece of equipment that costs more than a brand new Porsche C2S to confirm it either.
The manual says it takes 20 minutes to warm up without any qualification. Feel free to contact them for clarification. I don't own one, but if I did, I wouldn't take apart a calibrated piece of equipment that costs more than a brand new Porsche C2S to confirm it either.
it's difficult when I can't quote the last reply any more.... plus it seems we have very quick fingers.
I will do the research on my own to try to find more details/photos
I will do the research on my own to try to find more details/photos