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Old 12th May 2013, 07:24 PM   #421
Coris is offline Coris  Norway
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Well, I see your point, and agree in general. But in that example with a component which it run hot because somebody thought that is enough a little heatsink, instead of a much bigger one, to run that device cool, and having better performances, I can not agree.
If you can remember, it were a similar case (and discussion) about the processor in 95, which it were running with a very poor own cooling system. The Oppo designers added an heatsink to the lower dissipation processor in 105 model...
My earlier remark were not meant to offend all the engineers out there. It were referred to that designed product.
Everybody has one time or another appreciated (based on some reasons) that somebody else did stupid things. That it not for sure meant that all the world is stupid... Agree?

Why not read it and understand the texts as it is, without unnecessary extrapolations?

Last edited by Coris; 12th May 2013 at 07:44 PM.
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Old 13th May 2013, 12:30 AM   #422
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Quote:
Originally Posted by eganz1 View Post

The OPPO-105 is a technical tour de force.
Agreed. They really have upped the game in its standard form as it comes out of the factory. The clocking to the Sabre DAC is more careful and there are other subtle things. One I am not agreeing entirely with is the non-paralleling of the DAC's output phases, BUT it seems to work better with their post-DAC solution that it did in the '95, so you can't blame them for that.

But if somebody was after a stock '95 or '105 - then the added dollars of the '105 is worth it. Let's face, the number that are going to be modded or upgraded is very small.

I say it again - even to the phone enquiries I get - get the Oppo '105 even if you don't want to get it upgraded. It's great value for the money.

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Old 13th May 2013, 12:36 AM   #423
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Quote:
Originally Posted by Coris View Post
The Oppo designers added an heatsink to the lower dissipation processor in 105 model...
It is an improvement, but there is still a positive 15V regulator that get rather more warmer compared to its negative 15V brother (sister?) next to it. Comes down to the fact that the negative is mainly only for the post-DAC circuit, whereas the +15V has to drive a lot of other things. But at least the cooling through the top panel is better too.

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Old 13th May 2013, 07:57 AM   #424
Coris is offline Coris  Norway
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I'm not arguing about the heatsink on the processor of 105. It is a good thing, and it should be there. It were in my earlier post about a design decision Oppo taken comparing with the older model. I should want actually a bigger heatsink for 105... Of course the chip itself is much improved, dissipate less and for sure it can run in parameters at much higher temperature. BUT running the processor as cool as possible it improve the picture a lot. I only still wonder why the designers of the device did not observed this fact.

The positive 15v regulator it still be used to generate AVCC for DAC and some other needed lower tensions. As the difference between 15v and the lower regulated ones is quite big, the dissipation it still be important. Anyway, I agree that on 105 it is an improvement over the 95 model. But the power supplies need better filtering, special the analogue 5v one. 150 - 170mV ripple on this 5V rail is quite much. I removed the headphone noise floor in my device by better filtering for PSUs...

Last edited by Coris; 13th May 2013 at 08:13 AM.
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Old 13th May 2013, 08:17 AM   #425
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[QUOTE=Coris;3489076]I'm not arguing about the heatsink on the processor of 105. It is a good thing, and it should be there. It were in my earlier post about a design decision Oppo taken comparing with the older model. I should want actually a bigger heatsink for 105... Of course the chip itself is much improved, dissipate less and for sure it can run in parameters at much higher temperature. BUT running the processor as cool as possible it improve the picture a lot. /QUOTE]

Coris are you suggesting that the picture (as on the screen) would improve when the chip would be cooler?

jan
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Old 13th May 2013, 12:44 PM   #426
Coris is offline Coris  Norway
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Yes, I would say so...
You know, the idea with a fan inside the box is not bead. The problem is that a such fan make noise... I have mounted a bigger heatsink for the processor. Now is more easy to do this, because the holes are already in place. But anyway, this task is not an easy one...
The basic idea here is that the processor it may run at the coolest temperature one can get (one way or another).

Last edited by Coris; 13th May 2013 at 12:52 PM.
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Old 13th May 2013, 01:46 PM   #427
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I can not imagine any effect of the chip temp (as long as it within the spec of course) on the picture rendering. Do you have any more information about that?

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Old 13th May 2013, 02:08 PM   #428
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I think I have lost the thread - can we have some clarification - heatsink on the MediaTek chip?
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Old 13th May 2013, 06:06 PM   #429
Coris is offline Coris  Norway
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Quote:
Originally Posted by jan.didden View Post
I can not imagine any effect of the chip temp (as long as it within the spec of course) on the picture rendering. Do you have any more information about that?

jan
It is not about picture rendering here... Rendering it is made in QDEO chip, based on the digital data coming/decoded from/in MediaTeck chip.
There is here about thermal noises which increase in a quite complex data chip`s stages, and generate electrical noises. Such noises it may be added to the useful data, and taken as data... An extra check and filtering it may be necessary to get rid of more often errors. This mean more processing time and filtering which it may filter or affect the useful data...
Those things are very much simplified here, but are a lot complex. You can judge this thinking at your processor in your computer. A such processor is specified at 90 - 100 dg.C, and it have to work at that temperature. Do you know what happen when you actually run your computer`s processor at 90dg.C? Or 80dg.C? Or 70dg.C for enough long time? You can only try yourself.
There is a quite simple rule here: running cool = running smooth. Running hot = running hard to get rid of errors first, then do the job it have to be done. More errors, more wasting time...

There is no any benefit for the job to be done, to increase (thermal)noises in a electronic device. This issue have to be prevented. About this I think we can agree. In opposite, there is benefit to run that device cooler as one can do.

Oppo 95 it had a very poor cooling solution. The chip itself could reach 60-70 dg.C in normal drift. After I mounted a better cooling system, and I lowered the temp to 40dg. C, I could notice the increasing in picture quality.
Oppo105 it have a heatsink mounted o n MediaTek, there is a lower dissipation processor, and the running temp (on heatsink) it is approx 50dg.C. Lowering this working temp for the processor even more it have impact in picture quality. This impact is not dramatic of course, but is reflected in a way that is not very easy to be described. The fine details are revealed better, the tonal and gradient in colors is changing in positive way, and so on. The picture to be designed on the screen get use of more detailed informations, and this it is noticeable.
The same thing it happen when one use another (better) oscillator for the main processor. The same thing it happen when one filter better the power in the system. What mean this? Removing/preventing the noises to get into the system in different ways and at different levels: cooling down the hot running components, less jitter on the clocks, more clean power for the devices.
All those things have impact, each in its domain, and the all together`s result is to be visualised on the screen and hearable on audio outputs... Increasing in quality is at last obvious!

Of course it may be difficult for (some)one "to imagine" something like this (above). When that someone goes through all those things, step by step, do it by himself one or another, then one not need to imagine something at all: is just experience it...

BTW, rendering is a digital processing based on special algorithms, noises in a system is about physics... Quite different things....

Last edited by Coris; 13th May 2013 at 06:34 PM.
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Old 13th May 2013, 06:20 PM   #430
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CMOS digital chips (almost all processors are made this way now) do behave differently over their operating temperature.

Mostly, the effects are related to the increase in channel resistance when hot. This effect can reach tens of percent; not negligible!

The increased channel resistance reacts with the capacitance of succeeding stages, and slows down transitions - with increasing temperature. This should be of no consequence, provided the design is properly timed in the first place, and the intended ambient temperature range is not breached.

However, in the converse, when cold, the lowered channel resistance increases transitional currents, which puts greater demands on local power supply decoupling.
Again, it should all be incorporated in the design - but differences may arise.

A system with degraded picture in cold ambients may have suspect supply design or decoupling.

I'm not saying any of this is happening here - but it's not impossible.
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