I2S board that can be used in OPPO 103 and 203 is now developed.
With the HDMI type connector of PS AUDIO standard, DSD and SACD data as well as PCM file data can be transmitted to the outside via HDMI terminal conforming to PS AUDO standard.
The I2S signal from the main board is branched out simultaneously.
So that it goes to the internal DAC board on one side and the other to the outside.
The problem is that an HDMI type connector can not be mouned to the rear pannel of OPPO 203. In the near future, I m planning to produce a small amount of back panel that can mount HDMI Type I2s board and connector.
OPPO 103 and 203 can be selected with the jumper switch setting.
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I know there is not much demand, but some people have been asking steadily.
In the future, however, there is an increasing number of external DACs capable receiving the sacd and DSD data streams. Most of them conform to the PS Audio specification.
If it is HDMI connector's pin placement is different, it is solved by specially making HDMI cable.
This is an excellent job. I am planning to use a Cambridge Audio CXUHD as an audio transport with my next DAC project. The CXUHD is an Oppo203 optimised as a digit transport with no DAC. This would be a great addition. how do I buy one?
To those that have designed and built LPS for the 203/205:
Does the PSU supply +5V to the digital board or is +5V being fed back to the PSU to supply unpopulated parts? I just got my 203, lifted the lid to look at the PSU and can see +5V trace from CN5 to unpopulated D9/RL1 but I can't see any other trace to/from this pin. This would fit with heyj's comments about his LPS only supplying +12V to the digital board.
Also, does anyone have a part number for CN5? This is a different connector from what I have used on other projects. Of course I could redo the connector on the ribbon wire but it would be easier to have the compatible board header connector part.
Does the PSU supply +5V to the digital board or is +5V being fed back to the PSU to supply unpopulated parts? I just got my 203, lifted the lid to look at the PSU and can see +5V trace from CN5 to unpopulated D9/RL1 but I can't see any other trace to/from this pin. This would fit with heyj's comments about his LPS only supplying +12V to the digital board.
Also, does anyone have a part number for CN5? This is a different connector from what I have used on other projects. Of course I could redo the connector on the ribbon wire but it would be easier to have the compatible board header connector part.
+5v is not a power rail, but a control signal coming from main board, and is meant to activate the relay for the toroïdal transformer in 205 model. Oppo use the same new designed SMPS board for both models. This signal is also active for both models main boards.
If no any other better solution, I will recommend soldering the original (one end) cable to the power supply, dismissing so one connector, which it only worse the connection quality.
If no any other better solution, I will recommend soldering the original (one end) cable to the power supply, dismissing so one connector, which it only worse the connection quality.
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Thanks for the confirmation. I might map out a board using a high performance discrete regulator circuit I have used in the past with modifications to accommodate 3+ amps.
Later I may decide to purchase some of the main board upgrades you guys have done. I'm a bit wary though when I look at some of the pics shown here. I understand that trace lengths matter enormously in digital circuits, particularly when it comes to the efficacy of oscillators, due to parasitic inductances, EMC considerations etc. I see some relatively large boards for oscillator mods with long trace lengths created between input signals and their (ground) returns. But even though this is a DIY forum as opposed to a Vendor forum people seem reluctant to post schematics and board layouts so it is impossible to examine/verify. Maybe I am overly cautious. I've not delved into digital electronics yet. The 10 Best Ways to Maximize Emission from Your Product
On connectors, they're ubiquitous, convenient and work well. If I can't find the part used I will just rewire the ribbon side and use a Molex connector I've used in my high-end amp builds.
Later I may decide to purchase some of the main board upgrades you guys have done. I'm a bit wary though when I look at some of the pics shown here. I understand that trace lengths matter enormously in digital circuits, particularly when it comes to the efficacy of oscillators, due to parasitic inductances, EMC considerations etc. I see some relatively large boards for oscillator mods with long trace lengths created between input signals and their (ground) returns. But even though this is a DIY forum as opposed to a Vendor forum people seem reluctant to post schematics and board layouts so it is impossible to examine/verify. Maybe I am overly cautious. I've not delved into digital electronics yet. The 10 Best Ways to Maximize Emission from Your Product
On connectors, they're ubiquitous, convenient and work well. If I can't find the part used I will just rewire the ribbon side and use a Molex connector I've used in my high-end amp builds.
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I can not see any reason heaving a connection cable for DC 12v power, with two connectors. When about a production line for a mass production device, there is a good reason heaving a such two connectors cable... Connectors it however minimise the connection quality, especially for a DC rail.
In my opinion, it is not necessary using a high performance PSU (lowest possible noise) for DC powering a digital stage. The digital stage is however very noisy, and it will degrade the performances of a linear PSU, connected to a such digital stage.
The idea in this powering approach, is eliminating the huge noises amount added by a SMPS, to that digital stage, by using a much less noisy linear PSU. In this way the overall noise level into the system it will be lowered dramatically, (to the noise level of the digital system itself). The very low noise (performant) linear PSU it may not lower the overall noise level of the system, lower than that native it is already...
For a linear PSU powering a digital stage, it is enough heaving lowest possible ripple, good filtering, good output impedance, and stabilisation, as compensation for GND voltage drop on the quite long connection cable (Oppo devices case).
I suppose it may help if you can be more specific in your critics ("some pics shown here")...
In my opinion, it is not necessary using a high performance PSU (lowest possible noise) for DC powering a digital stage. The digital stage is however very noisy, and it will degrade the performances of a linear PSU, connected to a such digital stage.
The idea in this powering approach, is eliminating the huge noises amount added by a SMPS, to that digital stage, by using a much less noisy linear PSU. In this way the overall noise level into the system it will be lowered dramatically, (to the noise level of the digital system itself). The very low noise (performant) linear PSU it may not lower the overall noise level of the system, lower than that native it is already...
For a linear PSU powering a digital stage, it is enough heaving lowest possible ripple, good filtering, good output impedance, and stabilisation, as compensation for GND voltage drop on the quite long connection cable (Oppo devices case).
I suppose it may help if you can be more specific in your critics ("some pics shown here")...
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I agree regarding high performance LPS. I just happen to have most of the parts for the circuit and even more so already have the circuit in Eagle, meaning mapping out a board will be fast. Plus I know it is fully transient tested and stable etc.
I guess when I look at the pic in post 419 for example I see a huge board and worse, rather long wires from the digital board to connect to it and return. (I'm not talking about the power connections.) I understand millimetres matter in such applications so even seemingly short wires from the digital board to a sub-board 'upgrade' can undermine any benefits of a better oscillator part. Maybe I am wrong but I have seen cautions from very experienced digital EEs in other threads. So far I have played around only with high performance power supplies and amplifiers, nothing in the digital realm.
I guess when I look at the pic in post 419 for example I see a huge board and worse, rather long wires from the digital board to connect to it and return. (I'm not talking about the power connections.) I understand millimetres matter in such applications so even seemingly short wires from the digital board to a sub-board 'upgrade' can undermine any benefits of a better oscillator part. Maybe I am wrong but I have seen cautions from very experienced digital EEs in other threads. So far I have played around only with high performance power supplies and amplifiers, nothing in the digital realm.
@heyj
Where did you source your heatsink from and what is its thermal resistance (C/K)? I see you have a maximum current capability of just under 1.5A running your 35VA transformer at its limit (and secondaries in series). Even so, designing for that is a bit of a challenge when it comes to onboard heatsinking. The pass transistor can be required to dissipate a rather large amount of watts in heat if designing for continuous 1.5A operation. Obviously the numbers get a lot worse if designing for a higher continuous current need.
I designed continuous 5A circuits for another application but I had the pass transistors (Mosfet in that case as well; not as good as BJT) mounted directly onto the case wall of a Modu Dissipante 3U enclosure. Finding a heat sink that will fit on half a 15.5x10cm board and dissipate the required heat is a real challenge.
Of course, if the 203 doesn't come close to using a lot of current then things get considerably easier.
@coris
You used and recommend a 50VA transformer. What is the nominal secondary voltage of your transformer? Again, I'm trying to get to the maximum current expectations you guys have designed for since you have subjected your LPS to real use. Your pics suggest a minimal heat sink requirement which again suggests low current demands.
Designing for, say, 2.5A continuous, allowing enough headroom to maintain regulation at the possible low end of the mains supply voltage range, means the pass transistor in a discrete voltage regulator (and likewise an IC reg) could be asked to dissipate well more than 15W. That's a tremendous amount of heat for an onboard heatsink to handle. Let's say we find one that has a natural convection thermal resistance of 4.5C/W. So, using 15W, we have 68C above ambient and the ambient inside the enclosure is being raised by everything else producing heat (e.g. rectifying diodes etc). 30C ambient and that sink is very hot! (Even designing for 1.5A continuous the number is still 11W or more.)
I spent a couple of hours mapping out a board based on a Darlington BJT circuit. But I am pausing as LTspice modelling suggests those sort of currents demand massive heatsinking, well beyond what I can find to fit on the board (especially given the height limitation which appear fractionally over 50mm). Of course, one could just slap a good sink down and hope the current demands are never that high, but it would be great to leverage your previous experience. If you and heyj aren't running into thermal issues then the current used just can't be that high.
EDIT: I see you added some forced convection to generally lower the temperature inside the case.
The 50w transformer I chosen to use, it cover well for the needs of all the Oppo player models. More, the R core transformer is very efficient, and it can actually and very well, provide more power than it is rated for. I have designed my LPM (PCB) to fit for all models, accordingly populating the board. Also I have chosen a standard rated power transformer for my approach, as so it was more convenient for the project. The need for power are lower for the last models, as it use improved processors.
As I mentioned, the devices need for current is variable, as the way it function to fulfil different tasks. The max current for the PSU it have to cover the max needs, for a good and safe functioning. I test my LPM for 203/205 models for a max 3A, even thought, the continuous current used by these models is lower.
The amount of heat dissipation is not just as it seems to be out from calculations. I tuned my LPM for a minimum heat dissipation, and the heatsink is enough big for this purpose. The heatsink of my LPM is in thermal contact with the chassis bottom, so a large part of the heat it is dissipated this way. I use a forced ventilation, more for cooling the whole device, rather than for cooling the LPM.
There is a big quality gain when the main processor it is not working at high temperature. Natural convection in a such low enclosure as the 203 is, is totally inefficient, and actually not existing. In this conditions, adding a slightly heat source as the LPM it is in fact (its way of functioning), it increase enough much the overall working temperature of the device. This is not good. Therefore a slightly airflow inside the enclosure, created and controlled by a fan, it is indeed very efficient and it lower the working temperature to the room temperature. This it have an added impact for the overall signals quality gain, as well.
My advice to you, is building a linear PSU sustaining a max of 3A (12v), then connect it to your 203 player, and see (measure) everything you may need to know in this respect. Or a much more convenient alternative, getting a existent linear PSU, designed already for this purpose.
To be honest, I have to say that I used actually quite long time designing, developing and improving my LPM for these Oppo devices, and this it was an not cheap investment...
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There has been a lot of discussions on here about the merits of using LPM instead of the switching PS, but none about the 205's main toroidal transformer, which appears to me to be on the small size - I suspect done purely on economic grounds. Has anyone tried a higher rated transformer and its impact on creating a deeper more tuneful bass?
Well sure current demands are variable. And designing for peak or relatively short bursts of 3A (or more) is easy. The more pertinent question is what is average current need, say, when the player is in a 'relatively steady state' spinning a movie disk for 2 hours or more. If this settles at a more reasonable current demand then thermal issues get considerably smaller.
Normally one designs a power supply having a very good understanding of the supply needs. No one here designed the rest of the unit so there's some guessing and trial and error involved. I'm merely hoping to leverage the experience of you guys a bit as you have spent considerable time with the 203, 205 and prior models.
As always with LPS, managing thermal demands is a design challenge. (And for those that insist on unnecessarily massive filter capacitance, in-rush challenges.) The 203 isn't helpful in this regard because of the lightweight and shallow enclosure. It is quite possibly a very good idea to mount the pass transistor to the bottom of the enclosure and add some heatsinking on the underside. Maybe this becomes necessary. The good news is that such adaption can be readily accommodated by the board I've laid out. (Although annoying that the standoffs don't seem readily changeable.) I guess I just have to try things out with fingers crossed.
A small variable speed fan that is driven according to internal enclosure would be a nice addition too. But better that it is placed in the rear panel to pull hot air out of the enclosure rather than just circulating the hot air inside. There's room on the panel of the 203, not sure about the 205. I've not looked at the circuitry required to drive variable speed according to an NTC temp sensor but I doubt it is hard. Maybe something for later.
Normally one designs a power supply having a very good understanding of the supply needs. No one here designed the rest of the unit so there's some guessing and trial and error involved. I'm merely hoping to leverage the experience of you guys a bit as you have spent considerable time with the 203, 205 and prior models.
As always with LPS, managing thermal demands is a design challenge. (And for those that insist on unnecessarily massive filter capacitance, in-rush challenges.) The 203 isn't helpful in this regard because of the lightweight and shallow enclosure. It is quite possibly a very good idea to mount the pass transistor to the bottom of the enclosure and add some heatsinking on the underside. Maybe this becomes necessary. The good news is that such adaption can be readily accommodated by the board I've laid out. (Although annoying that the standoffs don't seem readily changeable.) I guess I just have to try things out with fingers crossed.
A small variable speed fan that is driven according to internal enclosure would be a nice addition too. But better that it is placed in the rear panel to pull hot air out of the enclosure rather than just circulating the hot air inside. There's room on the panel of the 203, not sure about the 205. I've not looked at the circuitry required to drive variable speed according to an NTC temp sensor but I doubt it is hard. Maybe something for later.
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Well, this fault it was done before by Oppo itself in the 95 design... A fan which work this way (on the rear panel), having contact with the air outside the enclosure, it will transmit all the generated audible noises outside as well. Such noise is indeed very annoying... More, the fan itself vibrations are to be transmitted and amplified by the chassis it is connected to (if no special measures are taken for damping).
My concept is heaving the fan (with its noises) inside the enclosure, generating or moving the inside air in a controlled very low airflow, allowing the air to transport and exchange the temperature with the whole enclosure surfaces. This it is enough and it lower the inside working temperature quite dramatically. A better approach is having the fan also placed inside the enclosure (and so, enough well phonically isolated), and only the air going in and out of the enclosure.
I implemented also this ventilation approach for 203 model, using new side panels with ventilation windows aesthetically placed, where the fresh air is admitted through the right window (over the main processor), and exhausted through left one (taking the inside warm from LPS as well). The fan inside it generate the very low airflow which it ventilate the device this way, completely inaudible, and very effcient...
Many ways to skin a cat so to speak. A fan venting directly to/from outside the enclosure will be much more efficient but, agreed, the challenge is to make sure it is quiet. That requires good parts, damping and variable speed according to temperature monitoring. Your side panels were a good idea.
I don't think it is something you can explain or quantify, a bit like using Schottkys on 50/60 Hz - this is an extract from a conversation from Paul McGowan of PS Audio in the Stereophile:
"What do you think a larger transformer is doing [that a smaller one wouldn't?]?
"I can't measure it, so this is purely speculative, but I think it's lowering the output impedance that's going to the circuit. When you demand current from a device—in other words, an output transistor—there is a tendency for the device to sag a bit. You can't really measure it, but every time I've taken a power supply and lowered its output impedance, the sound has improved dramatically. The only thing I can attribute this to is low DC resistance.' "