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Old 12th May 2013, 08:09 AM   #411
qusp is offline qusp  Australia
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ahh yes those stupid designers again have been outwitted by an amateur with a big mouth, zero experience in designing digital video circuits and lots of handwaving. 50c is nothing, its completely within the parameters of... well... everything, WELL within the parameters. Even the cheapest capacitors are rated at 85C and anything that has to deal with real heat is rated for 125C. active parts, will vary, but 50C is not hot, even a low noise device like the ESS is rated for 70C ambient. your comment about the designers not caring how the wires are routed is pretty rich coming from someone who fills his contraptions with flying wires and doesnt seem to take any care about the return path, or ground plane, EMI, RFI, anything, has no test gear and only considers that there is a problem if there is audible noise.

given its a picture, easily saved, how about you put your money where your mouth is and take a frame (digital, or if you prefer, analogue photo, you will need a tripod) before and after, it should be very easy to see the difference and very easy to perform a difference calculation to show only the difference.

but you wont do that..

Last edited by qusp; 12th May 2013 at 08:32 AM.
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Old 12th May 2013, 08:19 AM   #412
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Quote:
Originally Posted by Coris View Post
Not very special oscillator either, Even though the improvement in picture is obvious.
I recall that Martin Mallison of E.S.S., talking about multiplying and dividing clock frequencies at RMAF, he said there was definite advantages to dividing clock frequencies downwards (the opposite is s a definite no-no).

So maybe starting high and going low, despite potential penalties in that, maybe the advantages outweigh the disadvantages?

I have an open mind on that.

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Old 12th May 2013, 08:30 AM   #413
Coris is offline Coris  Norway
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The only problem with this going low (dividing frequency) is introducing jitter/skew. The higher the frequency of an oscillator, the better jitter figures. But using a divider with it`s own skew (added jitter) it may cancel the benefit of a better oscillator. This it may be a big dilemma... But, it seems that there are out there some good dividers too.
In this particular case here is about using a good clock/oscillator/frequency for ESS9018, and a little bit more added jitter to the divided (synchronized) frequency which goes to clock the MediaTek chip... I still wonder why it is noticeable an improvement in both picture and sound when only changing the standard/original resonator for MediaTek with a standard oscillator... And it still be improvements when clocking the same chip with a jittery frequency coming from a divider... It may be all this anyway better than the original clocking by resonator?
Experimenting is the way to find a better compromise.
As I said in earlier post, I could register improvements by only using quite common parameters devices in dividing 108Mhz (standard oscillator) with an modest quality divider. It looks like using better components, the improvements are guaranteed...
Keep working.

Last edited by Coris; 12th May 2013 at 08:46 AM.
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Old 12th May 2013, 09:03 AM   #414
Coris is offline Coris  Norway
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This is what I have got from the divider in this experiment...
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Old 12th May 2013, 09:14 AM   #415
skunark is offline skunark  United States
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One approach is use the divided clock as an enable with all flops running on the main clock . Skew will still be introduced with a typical clock tree, but there are several recipes to minimize or at least make the skew deterministic.
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Old 12th May 2013, 10:32 AM   #416
Coris is offline Coris  Norway
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I agree, but this is when one design/build the clock circuitry using quite discrete components. As usually one (simplest/minimalistic way) use integrated (monoblock) dividers, where is it not to have accesses to individual flip-flops...
I think it may work very well with good quality components, which can offer lowest possible skew. Those are in few ps range.
In this case, is the ESS9018 which it get the best clock, and this it is a main goal at least...
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Old 12th May 2013, 02:43 PM   #417
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Quote:
Originally Posted by qusp View Post
ahh yes those stupid...
What's eating you?

Contribute or don't. OK?
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Old 12th May 2013, 03:01 PM   #418
Coris is offline Coris  Norway
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I found also that multichannel stage it work very well at 108Mhz clocking. The clock signal it is transmitted to the second DAC by the mean of some differential circuitry and line. All those devices involved in this clock transmission it support well this quite high clock frequency.
I was not before into the multichannels part of the player, and this stage it is not yet modified. Making some measurements, I can see that here the output offset difference between every single channel is quite big and with +/- levels just by chance (but in the mV range anyway). As I expected and expressed long time ago, this variation (in production process), explain why they chosen an AC coupling.
It is interesting that on (measured) FL/FR channels there is an +/-DC offset before the caps, but after those caps there still exist an equal 2mV positive offset on both those channels.
Another thing, the offset control for the I/V stages is independent of the rest of the system. While on the main board this is 1,650v, on multichannels board it is 1,000v. All the I/V resistors have identical value here.
The clock frequency of 108Mhz for the DAC it make the multichannels stage (in this case FR/FL) sounds quite good without any modification... But with a little bit lower dynamic, not so wide and detailed soundstage, while a very high fidelity...
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Old 12th May 2013, 03:07 PM   #419
Coris is offline Coris  Norway
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Quote:
Originally Posted by Joe Rasmussen View Post
What's eating you?

Contribute or don't. OK?
Sorry for say that, but I couldn't ever read something about a real contribution form this poster. Only expressed criticism for all and everything other come with in this forum...
From my part I choose to just ignore his interventions.
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Old 12th May 2013, 08:06 PM   #420
eganz1 is offline eganz1  United States
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Well Coris,
I think we should give more credit to the engineers who create these devices that we buy.

The OPPO-105 is a technical tour de force.

The Panasonic plasma TV that I bought last year just astounds me with the images from Blu-ray.
Of course, these items are built to a price point, and consumers demand products at very low prices. It is this price pressure which produces the constraints that you have been studying in these products.

For those with the inclination, it also provides an opportunity to improve things…
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