If you can wait a little bit more, then it will be finished with my bran new designed I/V circuit/module based on OPA1632...
Else, from my part I was quite impressed by the way it works when using OPA1632. But this chip is not quite easy to work with it. First it works hot, and the heat it have to be well dissipated to not get important offset skews. There are some another difficulties in implementing OPA1632 as I/V, but when all the solutions are in place and working, then it brings quite high levels performances. And now, do not forget the cap over the DAC phases...
When about Oppo player. I will strongly suggest to pay attention to its own/internal power system. Is here first one may do some mods to get a clean power for its internal sensitive stages. One have to use the switching PSU inside the player (as designed), as this is the only one which it may be efficient for power hungry chips, processor, boards inside, and when about heat generating.
Better filtering, bypassing of the switching PSU is a must, carefully routing of the wires, shielding is to be recommended to get the best results. Then one may pay attention to the local regulators for the most sensitive circuits: clocks, DACs, analogue post DAC processing. Lower noise regulators do actually a good job in such cases.
After all these improvements are in place inside the player, and not enough satisfied with the results, I should think to improve the quality of the AC power (from wall) in general.
But anyway, heaving a trusted quality for the AC power system from the wall, one may goes in to details and improve what is inside the player.
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Coris,
thank you for the detailed response. Actually I mostly did the power filtering for my amplifier, and to separate the OPPO from the amplifier.
I'm interested in the OPA1632 solution, and how it compares to the alternatives. I see that they have a power pad variation which has much improved heat dissipation and thermal capability.
Eric
thank you for the detailed response. Actually I mostly did the power filtering for my amplifier, and to separate the OPPO from the amplifier.
I'm interested in the OPA1632 solution, and how it compares to the alternatives. I see that they have a power pad variation which has much improved heat dissipation and thermal capability.
Eric
There is right that is a version of OPA1632 chip which have better thermal dissipation (pad). I use that one.
After my PCBs will come, and it will be assembled, I intend to do quite extended measurements, both using 1792/94 and Sabre chips. So, one may have then something to compare with...
After my PCBs will come, and it will be assembled, I intend to do quite extended measurements, both using 1792/94 and Sabre chips. So, one may have then something to compare with...
Joe,
yes, I read your suggestions about the OPA-860.
In the thread, you were too modest to describe the results at the time.
In any case, you constrained yourself to using a chip that would fit in the same place SOIC at the same price. If we remove those constraints, would you still suggest the OPA-860, or maybe something else?
How will this compare to the alternatives?
Eric
yes, I read your suggestions about the OPA-860.
In the thread, you were too modest to describe the results at the time.
In any case, you constrained yourself to using a chip that would fit in the same place SOIC at the same price. If we remove those constraints, would you still suggest the OPA-860, or maybe something else?
How will this compare to the alternatives?
Eric
Coris,
I would recommend doing FFT / FR plots with a very good soundcard at 192k
SR to capture some of what is happening at > 20kHz.
cheers
IMO, you are better off with either:
1) discrete open loop I-V
2), a transformer based one or
3) one that integrates both discrete open loop + transformer.
I am currently playing with 3) and I think this is potentially the ultimate
solution. To do them well though is not easy.
Z
Too modest? That started my day with a laugh and I thank you for that - considering what has trasnpired in the last few days.
I would have preferred using the OPA-660, but they discontinued it and this is their replacement (ecept it isn't completely). So the replacement OPA-860 was a second best option and being SOIC, it could actually be used by Oppo if the wanted.
Downside: In the OPA-860, the Buffer side in an opamp - that's the bad news, but it seems to be a 'current' feedback opamp and very fast.
But how does it sound? Actually very very good and if you decide to do it, then I doubt you will be disappointed.
But the SAW clocking also makes a difference.
Just a few things I would do differently, see schematic below.
C1 should be 0.33uF.
R3 should be 220K and then check DC on the output and eliminate C4 output cap. That 220K could also be replaced by a Trimpot and null DC on the output. No caps in the signal path.
If you went ahead with this, we could discuss implemeting the SAW clocking.
If you decide to try OPA-660, then the above will also work, but I can't be specific with regard to values etc. You will have to work out those, but the OPA-860 works as shown and I was very pleased with the results.
Cheers, Joe
.
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The answer is part yes and part no. There are some things I am bound by. But I will suggest something in principle: Use a zero feedback low noise phono stage, sans RIAA EQ and add post-DAC filtering instead, and that is what I use, the idea came from the JLTi Phono Stage here, which is a commercial product that has been made by two companies.
But that OPA-860 circuit I suggested, is not that far off from what I do, and it is very good and I would love others to use it.
Cheers, Joe
.
Hi Terry, any chance of publishing it - I would be interested. Understand if answer is no.
Cheers, Joe
The Darbee tech does not interfere with what the QDEO does. Darbee's patent is centered on how the human eye perceives depth. The technology within the Darbee license uses this technology to allow us to better percieve depth cues in images (Darbee have patents). This has nothing to do witih QDEO, how well the Oppo player decodes video or it's color accuracy. Nor does the technology affect color calibration of the unit in any way.
The benefits of having the Darbee tech in the chain outweigh any of the assumed negatives you mention. That's why Oppo added the tech and also why many AV enthusiasts are buying the Darblet as a standalone device for their AV gear.
PS I dont work nor am I in any way affiliated with Darbee. Just pointing out that the tech does not interfere with the video or alter it in a way that hurts our visual perception of accuracy.
-Raja
Furthermore, the Darbee video processing is totally independent as you can simply disable it.
And most importantly the 105D improved on the 105 because in the 105 you have the sharpness control set on softening very slightly the picture, which is inaccurate, and you cannot defeat it, or readjust it with the sharpness control; it is there permanently and it is impossible to fix it! ...Even with a firmware update. There!
...No such thing in the 105D.
Simply put: The 105D is superior to the 105 which is superior to the 95.
...The latest the best.
And most importantly the 105D improved on the 105 because in the 105 you have the sharpness control set on softening very slightly the picture, which is inaccurate, and you cannot defeat it, or readjust it with the sharpness control; it is there permanently and it is impossible to fix it! ...Even with a firmware update. There!
...No such thing in the 105D.
Simply put: The 105D is superior to the 105 which is superior to the 95.
...The latest the best.
Thanks for your explanations on Darbee technique. I agree that Darbee it may be an improvement for picture. They developed a new filtering (hardware/software) technique, used first in sound, and it were expended further in video. Well, this is a progress. Is very well too that Oppo have implemented Darbee in the players, and in their one of the last mobile phone model, for the sound. I can well understand that it may be here not only about technical reasons in this collaboration...
I`m of course not against using of Darbee image processing in BDP105 or the later models.
My approach it were maybe not very clear explained, or it were a little bit misunderstood. I never meant that using Darbee processing it have a negative impact on the last Oppo player model...
OK, we know in general what Darbee do for the image. It process the image in real time to increase the details perception and the depth in a 2D picture.
I have to say that I observed exactly the same increasing in details and a better perception of the depth in video stage of a BDP105 model, only by replacing the standard 20Mhz oscillator of the QDEO chip with a better quality one. Better power supply for the same chip, and the oscillator, as lowering in general the HF noises in the system, by better filtering, decoupling, shielding, and so on. And of course a better quality oscillator for the main processor.
So, this it were my thinking, when I mentioned that with few quite small improvements in an existing 105 device, one could get the same improvements for the picture, as using a Darbee processor, in a 105D model...
That because my conclusion in my previous post, that Darbee processor it was not so necessary, IF one should improve a little bit more the actual design of the 105 model...
There is obvious for me that the depth perception in digital picture is in a close relation with the noise level in the imaging system. The noises due to the power, and clock systems. A cleaner video signal lead to quite dramatic improvements in the digital image details. Details increasing improve also the depth perception in a 2D picture.
Darbee video processing (patented) technique is to be used in noisy and/or relative low quality systems. This processing it happen in noise domain of the digital video signal. It filter actually the signal for the noises in a quite sophisticated way, in both hardware and software real time processing, with a dedicated processor.
I`m quite sure that this Darbee processing it will disappear when the UHD system it will be the standard for digital video. With that exceptional image resolution, one it will have the necessary image details to appreciate very well the depth of a 2D image... and will not need anymore the Darbee improvement. That because the video devices manufacturers it focus today on making the UHD technique as accessible as possible, and are not at all interested to invest more in further developing of the 3D image systems/devices...
PS. I do not mean here to minimize the Darbee efforts and progress in their video signal processing technique/improvement, but only to express my opinion in this case.
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Actually it is the other way around; the higher the resolution of your display (onscreen picture ultra high quality), the more effective the Darbee video processing is.
And it should be excellent with Ultra HD (4K).
Here I was strictly referring to the top Oppo model, the BDP-105D, as compared to all its predecessors. ...The stock BD players, not modified.
You are correct that noise and jitter artifacts affect the depth of an image. Certainly a cleaner power supply and better clock will help these things.
However, Darbee's patent revolves more around human eye perception and is independent of the effect clock jitter or power supply noise creates. Darbee's product decodes information that aids our eyes in perceiving depth. So whether or not you improve the 105 model with power supply and clock mods, the Darbee unit's addition in the chain still has positive benefits - you cannot replace what the Darbee unit does just by upgrading the power supply of a non-Darbee unit. While both things help depth, the Darbee unit does something that we cannot mimic by modifications.
-Raja
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There is of course not only the increased (hardware) resolution which it may improve the image perception... There are important the very fine details in the reproduced digital picture, higher amount of tonal levels, and huge amount of other parameters. In these areas the noise/signal ratio is that which decide...
Else I have serious doubt that (for a god while) the consumer accessible technology will permit to Darbee to apply its processing technique (in real time) to a so huge amount of data and the extreme necessary speed for doing this, when about 4k/8k digital video/picture...
But they can do well enough when about Darbee sound applications... I just wander if Darbee technology in sound improving (impulse response of the digital processing), by real time software processing, is not the same what we are talking about here, and some of us are doing by hardware means, when about that cap placed over the DAc outputs...
Darbee sound processing increase the weight of the sounds in a large spectre in a audio chain But to get such improvement one have to have a computer connected to the audio system, to software process the signal, using Darbeee algorithms...
We (some...) get almost the same improvements by only solder in that cap in the place...
To be further discussed...
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