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Old 20th August 2011, 12:04 AM   #1
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Default Clock Selection Experts?

I have a USB-I2S board which uses two Sunny SCO-020 oscillators. These are mounted in DIP 14 sockets, so trying something else would be really easy. The oscillators are 3.3 V models, and I cannot find any phase noise plots for them, or RMS jitter spec. I am wondering if anyone is familiar with the performance of these oscillators, and if there is anything else in DIP 14 which might improve performance. Maybe go to an smd oscillator with an adapter...Crystek CCHD?
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Old 21st August 2011, 05:13 PM   #2
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Default No ideas?

Oh well. I have decided to go with the new CCHD-957 oscillators from Crystek, and to adapt them to the board myself. Now I need to find a supplier for these oscillator modules.
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Old 30th August 2011, 03:13 PM   #3
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Hi,

You don't say what the frequency is but I assume it is 12.000Mhz ? Why are you set on 3.3V ? It really limits your choice.

There is quite a wide range available from cheapo smd to rubidium if your willing to do some diy. What's your budget ?

For me, best bang for the buck so far has been this :

ʯƼ100ѪƼ¾OCXO 0.01PPM-Ա

Dunno if you can get this where you are.

FWIW
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Old 30th August 2011, 04:02 PM   #4
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Default These are...

for upgrading an existing USB-I2S board. Two fixed oscillators:

22.5792 and 24.576, running on 3.3 VDC supply. I am not looking for ovenized clocks at $100s of dollars each, but low phase noise types like the new Crystek CCHD-957 (available ~8 weeks) seem like a good option. I was just wondering if anyone knows of any DIP 14 types with really high performance which would just plug right in. I am pretty sure I can adapt the CCHD-957s to the board, with some careful mods.
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Old 30th August 2011, 11:34 PM   #5
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Vanguard Ultra precision Golden TCXO, 0.3ppm 24.576MHz | eBay

I have used these and they are as good as it gets in dip14 and 3.3V. Very similar to tent lab xo. The 0.3ppm work with 3.3V and 5V, the 1ppm only work with 5V.

TBH, if you're upgrading the xo, you really should think about giving it clean power too.

If you really want a budget option then Euroquartz xo91 are low jitter smd parts.

Last edited by KlipschKid; 30th August 2011 at 11:44 PM.
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Old 6th September 2011, 12:05 AM   #6
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Quote:
Originally Posted by KlipschKid View Post
Hi,

You don't say what the frequency is but I assume it is 12.000Mhz ? Why are you set on 3.3V ? It really limits your choice.

There is quite a wide range available from cheapo smd to rubidium if your willing to do some diy. What's your budget ?

For me, best bang for the buck so far has been this :

ʯƼ100ѪƼ¾OCXO 0.01PPM-Ա

Dunno if you can get this where you are.

FWIW
When dealing with Chinese vendors - proceed with caution!

The specification sheet looks fancy but not worth the paper it's written on.

Google Translate

GOLDY۾ϵ(5)------ SC-CUT OCXO𱬳¯ - DIY̳ - HIFIDIY̳ - Powered by Discuz!

Certainly not SC-cut, probably not as good as Tent / Crystek

T
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Old 6th September 2011, 12:13 AM   #7
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Default I am

going to go witht he Crystek CCHD-957s when they become available (still 6-8 weeks out). The digital guys I believe in most all seem to talk about phase noise at low frequencies as the most important criteria, and the CCHDs shine in this area-purpose built oscillators for audio.
Of course, totally good call on power supply, no clock will perform its best with a bad supply. Right now the board gets its 5 VDC overall supply from a LiFePO4 battery pack, with a dexa pre-regulator followed by 4x1000 uF of Elna Cerafines. I am trying to decipher which board level regs supply the 3.3VDC clocks, but board level detective work on this tiny smd populated board is tricky. I have a nice mini shunt to use to power the clocks if I can figure it out...
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Old 6th September 2011, 03:08 AM   #8
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Originally Posted by Terry Demol View Post
When dealing with Chinese vendors - proceed with caution!

Certainly not SC-cut, probably not as good as Tent / Crystek

T
Yep, I completely agree - lots of fakes, lots of caution. For me, it really helps to be a local but I have a western face so I still get more than my fair share of people trying to rip me off.

The items I recommended are from personal experience not second hand third party posts on the internet. I'm sure we're all aware that many people who post stuff on the internet are not reliable so you have to test everything and decide yourself.

I have a Tent Labs too, and I found the Vanguard 0.3ppm to be very similar to the Tent Lab xo module in terms of the definition it gave. I've tried them both in 5V and 3.3V systems and I've actually left the Vanguard in the upsampling cd player rather than the Tent because the Tent seems to be able to do better when it is given a really clean supply and the supply in the cd player is ordinary 3 pin reg. The Vanguard suits this better.

The ocxo has pipped them both so regardless of whether it meets the seller's specs, it is still a very good clock. There's more depth and space and vocals come forward more and seem smoother. However, it takes time to warm up and that's something I'm not so keen on. I don't want to turn on the hifi and then come back 30 minutes later to listen, but despite this, it has stayed because it does sound good. It also needs a cleaner regulated supply because the board it comes with doesn't have enough ripple rejection etc to get the best from the clock. I'm still experimenting with this but so far a 12V sla battery is working very well.

There are still a few more clocks out there for me to try. I'd be very interested to hear from anyone who has compared the Tent to the Audiocom superclock as that is next on my list.

Last edited by KlipschKid; 6th September 2011 at 03:13 AM.
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Old 6th September 2011, 03:26 AM   #9
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Quote:
Originally Posted by barrows View Post
going to go witht he Crystek CCHD-957s when they become available (still 6-8 weeks out). The digital guys I believe in most all seem to talk about phase noise at low frequencies as the most important criteria, and the CCHDs shine in this area-purpose built oscillators for audio.
Of course, totally good call on power supply, no clock will perform its best with a bad supply. Right now the board gets its 5 VDC overall supply from a LiFePO4 battery pack, with a dexa pre-regulator followed by 4x1000 uF of Elna Cerafines. I am trying to decipher which board level regs supply the 3.3VDC clocks, but board level detective work on this tiny smd populated board is tricky. I have a nice mini shunt to use to power the clocks if I can figure it out...
The Crystek phase noise does look very impressive but I can't see any info about jitter or stability. http://www.crystek.com/crystal/spec-...k/CCHD-957.pdf

When you get the clock, please post your impressions and any clock you can compare it to please.

I'm also interested in how you regulate the battery to remove battery noise. :-)

Last edited by KlipschKid; 6th September 2011 at 03:32 AM.
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Old 6th September 2011, 10:13 AM   #10
oshifis is offline oshifis  Hungary
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Hi clock experts,

Does it make sense to replace the original SC-cut 10.000 MHz crystal in an OCXO to a plain 11.2896 MHz crystal removed from a CD-player?
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