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Old 10th December 2012, 07:04 PM   #1661
TNT is offline TNT  Sweden
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If thats Hz on the x-axis it's one of the better I have seen. Whats the cost? What frequencies are available? Link? Oven is overkill... the usual box and the fact that D/A are are usually used indoors makes it unnecessary.
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Old 10th December 2012, 10:06 PM   #1662
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Quote:
Originally Posted by TNT View Post
If thats Hz on the x-axis it's one of the better I have seen. Whats the cost? What frequencies are available? Link?
This is a sample I got from HCD and it's a custom part, so any frequency could be available. About a production, the minimum order quantity is 5 pcs and break price are:
- 5 pcs 294.10 euro each
- 10 pcs 271.54 euro each

Quote:
Oven is overkill... the usual box and the fact that D/A are are usually used indoors makes it unnecessary.
Since it use an SC-cut crystal the oven is essential. SC cuts have an inflection temperature of about 92C and are very flat at the hotter end, but tail off quickly on the cold end. The proper operating temperature for an SC-cut crystal is usually in the range of 80-100C, then they are usually used under constant hot temperature, just as in Oven Controlled Crystal Oscillator.
Note that only SC-cut crystal reaches very high Q (from 300-400k up to 1M and over), which normally allows to get excellent performance in phase noise (frequency domain) and usually low jitter (time domain).
Unfortunately an SC-cut crystal and consequently an OCXO have a disadvantage: the price. For that reason they are not usually implemented in audio application. I remember only a few device, very expensive, using that way; conversely they are often used in professional analog to digital conversion, as the master clock of the entire system.
An OCXO guarantees a very high long term stability, useless in audio digital to analog conversion, but it also guarantees high short term stability in the frequency domain, essential in audio application to get low jitter.

Andrea
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Old 10th December 2012, 10:54 PM   #1663
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Originally Posted by iancanada View Post
Step1: Remove R22, R23, R24, R25 from PCB. SMT soldering station is recommended tool, but normal solder iron is still OK.

Setp2: Cover the GND pads of R23, R24 and R25 with fine cut high temperature tape to avoid signals short to GND.

Setp3: Solder the 4P SMT PH2.0 header, Pin1 (WS) to R24 signal pad, Pin2 (SD) to R25 signal pad, Pin3 (SCK) to R23 signal pad and Pin4 to both R22 signal pad and GND pad,

Step4: Cut the solder mask paint beside the both GND pads of the header appearing small area of GND copper plate, please be careful no touching any other circuit route.

Step5: Solder the support pads of the header to the appeared GND copper plate. Solder iron with higher power may require. For enough support force, applying compound of strong glue (such as epoxy) is highly suggested for double support.

Step6: Make an I2S cable to introduce an additional I2S input source.

The Digikey P/Ns are:
Connector header: 455-1736-1-ND
House: 455-1164-ND
Terminal pin: 455-1127-2-ND

Ian
Hi Ian,

Do I read allright that I have to ground (short) the signal- and the grnd pad of former resistor 22 ? I found out after I placed the connector. But if I shoud short the two, I can make just a grnd connection with pin 4.
Please could you confirm?
Thanks!
Ed
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Old 11th December 2012, 12:49 AM   #1664
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Quote:
Originally Posted by andrea_mori View Post
This is a sample I got from HCD and it's a custom part, so any frequency could be available. About a production, the minimum order quantity is 5 pcs and break price are:
- 5 pcs 294.10 euro each
- 10 pcs 271.54 euro each


Since it use an SC-cut crystal the oven is essential. SC cuts have an inflection temperature of about 92C and are very flat at the hotter end, but tail off quickly on the cold end. The proper operating temperature for an SC-cut crystal is usually in the range of 80-100C, then they are usually used under constant hot temperature, just as in Oven Controlled Crystal Oscillator.
Note that only SC-cut crystal reaches very high Q (from 300-400k up to 1M and over), which normally allows to get excellent performance in phase noise (frequency domain) and usually low jitter (time domain).
Unfortunately an SC-cut crystal and consequently an OCXO have a disadvantage: the price. For that reason they are not usually implemented in audio application. I remember only a few device, very expensive, using that way; conversely they are often used in professional analog to digital conversion, as the master clock of the entire system.
An OCXO guarantees a very high long term stability, useless in audio digital to analog conversion, but it also guarantees high short term stability in the frequency domain, essential in audio application to get low jitter.

Andrea
Quite well explained here:
SC-cut Frequency vs. Temperature Curves
Crystal Technology

Only 700$ US$ for a dual clock setup it's a bargain! At these prices I think I will pass

Will you compare it with the CCHD-957 in a critical listening test?
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Old 11th December 2012, 01:06 AM   #1665
qusp is offline qusp  Australia
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that and finding a way to make sure you can control it correctly with fifo
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Old 11th December 2012, 02:25 AM   #1666
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Originally Posted by ed linssen View Post
Hi Ian,

Do I read allright that I have to ground (short) the signal- and the grnd pad of former resistor 22 ? I found out after I placed the connector. But if I shoud short the two, I can make just a grnd connection with pin 4.
Please could you confirm?
Thanks!
Ed
Yes, R22 short to ground by pin4 of the connector.

Ian
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Old 11th December 2012, 11:44 AM   #1667
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thanks for the confirmation, Ian.
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Old 11th December 2012, 01:03 PM   #1668
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Quote:
Originally Posted by Fridrik View Post
Quite well explained here:
SC-cut Frequency vs. Temperature Curves
Crystal Technology

Only 700$ US$ for a dual clock setup it's a bargain! At these prices I think I will pass

Will you compare it with the CCHD-957 in a critical listening test?
I received the sample yesterday, so I have not yet test its sound performance.

This is a custom OCXO, so inevitably it's not a cheap solution.
As I know, nobody produce OCXO at frequencies suitable for digital to analog conversion as a standard item.

BTW I'm following an alternative way to reach similar performance at lower cost, with an high quality AT-cut crystal in a dedicated circuit
Ian asynchronous I2S and S/PDIF FIFO KIT group buy
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Old 11th December 2012, 03:58 PM   #1669
TNT is offline TNT  Sweden
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Quote:
Originally Posted by andrea_mori View Post
This is a sample I got from HCD and it's a custom part, so any frequency could be available. About a production, the minimum order quantity is 5 pcs and break price are:
- 5 pcs 294.10 euro each
- 10 pcs 271.54 euro each


Since it use an SC-cut crystal the oven is essential. SC cuts have an inflection temperature of about 92C and are very flat at the hotter end, but tail off quickly on the cold end. The proper operating temperature for an SC-cut crystal is usually in the range of 80-100C, then they are usually used under constant hot temperature, just as in Oven Controlled Crystal Oscillator.
Note that only SC-cut crystal reaches very high Q (from 300-400k up to 1M and over), which normally allows to get excellent performance in phase noise (frequency domain) and usually low jitter (time domain).
Unfortunately an SC-cut crystal and consequently an OCXO have a disadvantage: the price. For that reason they are not usually implemented in audio application. I remember only a few device, very expensive, using that way; conversely they are often used in professional analog to digital conversion, as the master clock of the entire system.
An OCXO guarantees a very high long term stability, useless in audio digital to analog conversion, but it also guarantees high short term stability in the frequency domain, essential in audio application to get low jitter.

Andrea
OK, so You mean that the close in phase noise 0-100 hz is not possible on this level if the crystal is not heated?

/
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Old 11th December 2012, 04:11 PM   #1670
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Originally Posted by TNT View Post
OK, so You mean that the close in phase noise 0-100 hz is not possible on this level if the crystal is not heated?

/
I mean SC-Cut crystal does not work at ambience temperature.
And I also mean similar phase noise performance is very difficult to reach with an AT-Cut crystal. See Crystek specs and compare with HCD OCXO.
I'm trying to reach something of similar with the Laptech AT-cut crystal, but it's a cold welded and polished crystal that cost 2 times the Crystek.
Without a good crystal you cannot build a good oscillator. PLL or similar solution, do not solve the problem coming from a bad crystal, at least in audio application.
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