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Author Topic: Rubidium Atomic clock  (Read 5562 times)

Alécio Costa - Brazil

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Rubidium Atomic clock
« on: December 29, 2007, 02:20:00 PM »

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Alécio Costa Studio
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mcsnare

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Re: Rubidium Atomic clock
« Reply #1 on: December 29, 2007, 02:33:27 PM »

One of the guys from the company was taking a demo unit around town a few months ago. I didn't hear it but everyone I talked to thought they heard an improvement when using the Atomic for clock. I'd like to hear the Isocrone and see if that improves the sound. I know that technically an external clock should not improve performance, I'm just sayin'......
Dave

Jerry Tubb

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Re: Rubidium Atomic clock
« Reply #2 on: December 29, 2007, 04:34:19 PM »

Is that the same Rubidium clock Roger Nichols was using about a decade ago?

JT
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Terra Nova Mastering
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Larrchild

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Re: Rubidium Atomic clock
« Reply #3 on: December 29, 2007, 07:10:05 PM »

Cesium-Beam and Rubidium frequency references are all over ebay now that GPS has replaced many free-standing sources.

 http://search.ebay.com/search/search.dll?sofocus=bs&sbrf  tog=1&dfsp=1&from=R10&satitle=rubidium&sacat  =-1%26catref%3DC6&sargn=-1%26saslc%3D2&sadis=200& ;amp  ;fpos=90036&sabfmts=1&saobfmts=insif&ftrt=1& ftrv=1&saprclo=&saprchi=&fsop=1&fsoo=1

http://search.ebay.com/cesium-beam_W0QQfromZR41

Which begs the question: "If they are now locking to GPS reference, why can't we?"

All the broadcast stations do it.

http://search.ebay.com/search/search.dll?sofocus=bs&sbrf tog=1&dfsp=1&from=R10&satitle=gps+oscillator& ;sacat=-1%26catref%3DC6&sargn=-1%26saslc%3D2&sadis=2 00&fpos=90036&sabfmts=1&saobfmts=insif&ftrt= 1&ftrv=1&saprclo=&saprchi=&fsop=1&fsoo=1
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Larry Janus
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J.J. Blair

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Re: Rubidium Atomic clock
« Reply #4 on: December 29, 2007, 07:28:35 PM »

Sure, the atomic clock is 144,000 times more accurate than crystal, and sounds better.  But if the music sucks, does it really matter?
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Larrchild

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Re: Rubidium Atomic clock
« Reply #5 on: December 29, 2007, 07:32:22 PM »

On the odd-chance a good one gets through, you have to hedge your bets.
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Larry Janus
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dcollins

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Re: Rubidium Atomic clock
« Reply #6 on: December 29, 2007, 11:12:05 PM »

Larrchild wrote on Sat, 29 December 2007 16:10


Which begs the question: "If they are now locking to GPS reference, why can't we?"

All the broadcast stations do it.



Because they need the great long-term accuracy (like loses a second every billion years) and audio wants great short-term accuracy (like 10^-12 jitter).

Has there ever been a review of an external clock where the sound was made worse?


DC

Larrchild

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Re: Rubidium Atomic clock
« Reply #7 on: December 29, 2007, 11:22:56 PM »

I wanted to park outside your place and transmit jittery psuedo GPS signals, shoot, I'm crestfallen. Rolling Eyes

I get it, long term is irrelevant here.
Even with a Long-Playing album.
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Larry Janus
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bruno putzeys

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Re: Rubidium Atomic clock
« Reply #8 on: December 30, 2007, 05:19:07 AM »

dcollins wrote on Sun, 30 December 2007 05:12

Larrchild wrote on Sat, 29 December 2007 16:10


Which begs the question: "If they are now locking to GPS reference, why can't we?"

All the broadcast stations do it.



Because they need the great long-term accuracy (like loses a second every billion years) and audio wants great short-term accuracy (like 10^-12 jitter).

Spot on. Of all the audio myths I've seen promoted lately the one that surprises me most is that sound quality should improve with absolute accuracy. It's like claiming the positional stability of a puppy on a leash is improved by tying the leash to a lamp post located exactly on the equator instead of another one down the road.

Guido Tent has knocked together a reference oscillator that we use to calibrate house syncs for people who need grade 1 accuracy. The reference oscillator puts out 44.1k and 48kHz within 0.01ppm. The output is phenomenally jittery, you can see it rattle on a scope. Point is, the actual oscillator is an oven oscillator at 10.000MHz. To get audio rates, a PLL is added. Since jitter doesn't matter when all you need is an exact frequency over the long run, a 74HC7046 (!!!) is used for that.

I daresay rubidium oscillators also don't come at audio rates so you'll always need to slap on a PLL or a digital synthesizer. Whether the result is any good for audio (ie. jitter performance) is entirely determined by *that* circuit.
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minister

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Re: Rubidium Atomic clock
« Reply #9 on: December 30, 2007, 03:19:49 PM »

Bruno Putzeys wrote on Sun, 30 December 2007 04:19

Spot on. Of all the audio myths I've seen promoted lately the one that surprises me most is that sound quality should improve with absolute accuracy. It's like claiming the positional stability of a puppy on a leash is improved by tying the leash to a lamp post located exactly on the equator instead of another one down the road.

How else can you ensure the Absolute Puppy Phase for your dog?

Puppy Chow In : Puppy Chow Out.  makes clean up easier.



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dcollins

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Re: Rubidium Atomic clock
« Reply #10 on: December 31, 2007, 12:23:16 AM »

minister wrote on Sun, 30 December 2007 12:19


Puppy Chow In : Puppy Chow Out.



Clearly you are not a dog owner.

DC

crna59

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Re: Rubidium Atomic clock
« Reply #11 on: December 31, 2007, 12:30:15 AM »

minister wrote on Sun, 30 December 2007 14:19


How else can you ensure the Absolute Puppy Phase for your dog?



My Puppys are in phase!  Laughing

Regards,
Bruce
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Larrchild

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Re: Rubidium Atomic clock
« Reply #12 on: December 31, 2007, 01:17:31 AM »

I figured you would have to slave a lower-jitter vco to it, but I didn't realize it would throw jitter in so violently. They have these "GPS Disciplined" TCXO's that seem pretty usable though. Same idea, I guess. A dog sitting in the hot, equatorial sun, thinking:"I'd rather be taking orders from a 1/4" round piece of quartz, right now, somewhere cooler."

Quote:

It's like claiming the positional stability of a puppy on a leash is improved by tying the leash to a lamp post located exactly on the equator instead of another one down the road.

Disclaimer: No Dogs were harmed during this metaphor!
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Larry Janus
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bruno putzeys

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Re: Rubidium Atomic clock
« Reply #13 on: December 31, 2007, 05:43:44 AM »

I'm not saying a PLL *necessarily* adds this kind of dirt. What I mean is that the presence of a precise frequency standard means nothing to audio quality if the PLL isn't up to scratch.

What I fear is that someone simply decided "oh clocks seem to sell, let's do something with rubidium - I'm sure that'll resonate well with the customers".
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zmix

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Re: Rubidium Atomic clock
« Reply #14 on: December 31, 2007, 02:05:11 PM »

I spent quite a bit of time listening to this clock in a variety of studios here in NY.  It was gratifying to compare notes with another engineer and discover that we had each heard the same things, but our observations were at odds with the sales rep's claims.

YMMV

CZ

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