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Old 3rd January 2013, 04:00 PM   #201
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Quote:
Originally Posted by couch View Post
PS: Joe, you're welcome to use anything from my first post that you think stands up to scrutiny. It's courteous of you to ask. Just consider it thought experiments--fair game for scientific challenge and correction.
Thought experiments are good, I use them all the time, especially in my work in loudspeaker design.

Take this one: You invite a subject into a room, you show him a desk and on the desk is a large piece of paper with a very intricate continuous line, with a starting point and an end. You give the subject a pen and ask him to trace that complex line and tell him not to hurry, even if a clock is going while he is doing the task, and he can have all the time he needs, and he simply needs concentrate on getting every detail right.

The you tell him to start as you click the clock on. At first he is doing really well and then he starts to sense something odd. You see the room is actually on springs and it is starting to move about erratically from forces he cannot see (is not allowed to). It is soon obvious that his task has become much harder than he ever thought and that now he will make many mistakes.

See the point? If those intricate lines to be traced represents high frequencies, then what happens at even ultra-low frequencies will affect the end result.

This is a thought experiment that helps us to understand the nature of stability and that ultimately it is related to Terra Firma, that which is beneath our feet. If it moves, you are up the creek.

Phase noise ("jitter") is commonly measured down to about one Hertz.

What if we compare two clock/oscillators, and the one with inferior phase noise above one Hertz sounds better than one that is superior in phase noise, i.e. lower above one Hertz?

This is the question raised in post #169 Oppo`s BDP105 - discussions, upgrading, mods...

What is happening below that one Hertz?

And since now we are talking in stability in time that have equivalent frequency way below where there is musical content, how can that be? The above thought experiment may offer an explanation.

Greater than 10 seconds, 100 seconds, a THOUSAND seconds?

If the SAW sounds better than the Crystek - as Coris says - then what is going on? Above one Hertz the Crystek is better. So it is supposed to sound better.

Hence it is now important for others to do the SAW versus Crystek 957 comparison.

If there is a great consensus that the SAW is superior, then we have an incentive to find out what is going on!


Cheers, Joe R.
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Old 3rd January 2013, 05:24 PM   #202
Coris is offline Coris  Norway
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Quote:
Originally Posted by Joe Rasmussen View Post

If the SAW sounds better than the Crystek - as Coris says - then what is going on? Above one Hertz the Crystek is better. So it is supposed to sound better.

Hence it is now important for others to do the SAW versus Crystek 957 comparison.

If there is a great consensus that the SAW is superior, then we have an incentive to find out what is going on!


Cheers, Joe R.
I want to express her my opinion that I consider as enough unfortunate that it seems that I`m yet the only one who is cited as above...
The SAW oscillators are not expensive. That because it will be very fortunate if many DIY-er will get the opportunity to try it, tested, used in DACs and so on. As experiment. And not at least, come here and publish their impressions, conclusions, results, measurements. Only then we can have an quite objective conclusion: better or not than those very expensive oscillators, with very good jitter figures, etc.
I may correct a little bit the above assertion about my appreciation of the sound using an SAW oscillator vs a Crystek one: my opinion is that an SAW 125Mhz sounds better than an 100Mhz Crystek on ESS9018. I did not heard yet the resulted sound out of this DAC chip, when clocking with an 125Mhz Crystek, and with an 125Mhz SAW oscillator. Such comparing it may be the right one.

Last edited by Coris; 3rd January 2013 at 05:53 PM.
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Old 3rd January 2013, 05:40 PM   #203
Coris is offline Coris  Norway
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Originally Posted by Coris View Post
About wiring of the oscillator here I will think to an analogy with the 95 model. It may be the similar design, and the chip for sure do not have any changes for the clock pins, comparing with the old model.
So, in 95 model the clock were injected on X1 crystal tab 3 (pin 3). I think the designers used the processor corresponding pin as clock IN and another corresponding pin as clock OUT. This design it may also be similar for the 27 Mhz clock on backside of the motherboard of 95 model. There may not be important reasons that this "logic" and design it will be modified for this new processor model (105).
So, my supposition is that the clock IN pin of the processor it may be connected to the pin 3 of the 27Mhz crystal (105 model).
I fully agree that the most reasonable way is to remove the passive components around this crystal to isolate it, and do not desolder it out from the board.
I will want to identify the trace which goes from the pin 3 of the crystal to the processor, and I will want to try first to connect there the new clock signal (after isolate the crystal).
There are of course 50/50 chances that this logic may be true. So if it does not work this way, then one may connect the clock signal to another processor pin...
In general the design of such clock inputs are made to function well for both way of use: crystals and oscillators. So, may not be catastrophic if one connect the oscillator output on the so called output clock pin of the processor. I will want to use first an 27Mhz oscillator as clock, to see that all may function as it should, and then try something else...
About this above subject, I may say that I forgot something quite important.
Before doing any modification here, I will want to measure first the amplitude of the oscillations on those two clock pins of the main processor. I just suppose that on this new model of Oppo processor it may be changing of the needed clock amplitude signal, comparing with the precedent processor (used in 95). This aspect may be important when modding in this area.
It is enough important to know what kind of oscillator it may be used here: 3,3V, 1,8V or something else.
Then, I will want to cut the traces which goes to the processor, isolate the oscillator components, and measure those components. Then remake the connections, remove the passive components around the crystal, and at last connect an external (custom) oscillator, which will deliver an clock signal with the same (measured) amplitude as the original one.
In my opinion this way it may be a safe one...
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Old 4th January 2013, 11:03 AM   #204
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I have used both 100MHz and 125MHz SAW - noticed no real difference other than 125MHz became noisy (sounded like static a bit) on one Oppo 95 I did and it was OK with 100MHz SAW.
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Old 4th January 2013, 01:49 PM   #205
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I could never noticed any noise using either 125Mhz clock or 122Mhz or something else over 100Mhz. Just very good sound...
I`ve got only sparkling like noises in silence/in between tracks, when I used 133Mhz oscillator. I have my own analogue circuit design after DAC, without any filtering (32mVpp residual HF noise on final opamp output, for an max 28Vpp audio signal).
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Old 4th January 2013, 11:43 PM   #206
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Quote:
Originally Posted by Coris View Post
I could never noticed any noise using either 125Mhz clock or 122Mhz or something else over 100Mhz. Just very good sound...
I`ve got only sparkling like noises in silence/in between tracks, when I used 133Mhz oscillator.....
It clearly varies according to the player. I have my own at 125MHz right now and I get some slight noises. I did another player after that and at 125Mhz was very much more noisy, this was fixed when 100MHz SAW was fitted. So since I am doing, not a single player but players, I have to stay safe. I have now done 100MHz on a number of players and they don't sound much difference to 125MHz.

Cheers, Joe R.
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Old 9th January 2013, 03:12 AM   #207
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54MHz SAW Oscillator:

On Digi-Key website they call this a SAW Oscillator and available in 54MHz:

KC5032A54.0000C10E00 AVX Corp/Kyocera Corp | 1253-1054-1-ND | DigiKey

The Datasheet does not mention "SAW" but does say "High Frequency" and the range starts at a low 50MHz (up to 170MHz), so this sounds like a SAW unit.

I am sending AVX/Kyocera and email, to see if they can confirm SAW.

The 54MHz should be convertible to 27MHz using the 74HC4040N divide-by-two I posted earlier in:

Oppo`s BDP105 - discussions, upgrading, mods...

It is the smaller form factor of 5x3.2mm - but that's OK - and 1.6V to 3.63V DC range.

Make sure 4040 chip is the NXP 98 MHz version as other 4040 don't have sufficient bandwidth. Element14 part #380880.

Cheers, Joe R.

PS: Alas Digi-Key does not have stock and quoting Feb 20th.
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Old 9th January 2013, 04:33 AM   #208
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Correction - available range of the KC5032A-C1 is 50MHz to 133MHz. The fact the lowest is 50MHz does support that it is what Digi-Key claims, a SAW. But it seems they don't stock any of them - you have to place order and wait.
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Old 9th January 2013, 06:14 AM   #209
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..............................................

I found it at Digikey an 54 Mhz oscillator (PN 1253-1054-1-ND) which is specified as "Type SO (SAW)"... I can not see in the data sheet something about SAW type... I think I will give it a try anyway to this and another similar one 27Mhz.
Redundancy...
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Old 9th January 2013, 06:42 AM   #210
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It may be easier to get 53.125MHz SAW than 54MHz. Divide by 2 gets us 26.565MHz.


I wonder how critical 27MHz actually is - 26.565MHz is 1.6% lower in frequency.

Is the Crystek 957 available in 27MHz?

ALSO - is this a SAW oscillator from Crystek - when the range starts at 50MHz and upwards, then there is a chance it's a SAW:

http://www.crystek.com/crystal/spec-sheets/clock/CCHD-575.pdf

Cheers, Joe R.

PS: Crystek makes another oscillator called "CVS575S-500 - a 500MHz Voltage Controlled SAW (surface acoustic wave)
Oscillator, or VCSO. SAW crystal technology provides low-noise and low-jitter performance with true sinewave output."
Note
that they have 575 in common.

Makes you think?
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