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ES9038Q2M Board
ES9038Q2M Board
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Old Yesterday, 09:33 AM   #2781
eziitis is offline eziitis
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Join Date: Aug 2016
this kind of: NEW ES9028 ES9028PRO DAC DSD decoder high quality assembled board for hifi audio | eBay

apparently the chip sources/sinks 16mA.
in i/v it had 560R FB, which caused clipping at 0dB, so after changing it to 250R, I got 4V p-p after i/v, what then is in the linear region for LME49720 i think.
obviously the stock LPF should be changed as well, with Fc about 50kHZ for DSD.
sound is improved of course, more relaxed without "shattering glass" tint.
what is puzzling, only AD797 gave clean spectrum, for all others 2nd harmonic present.

and I was wondering how then the TH mod ES9038q2m sounds now?

Last edited by eziitis; Yesterday at 09:35 AM.
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Old Yesterday, 09:45 AM   #2782
Markw4 is online now Markw4  United States
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Join Date: Jul 2016
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That looks like the dac board Mikett is working on in his other thread. Sometimes he mentions something about it here. The main thread for that is here: Moving from 9038Q2M to a 9028Pro board

However, I don't think you want 4v peak to peak out of the IV if it drives the output negative at all. If AVCC is 3.3v then Vref should be 1.65v. If IV swing is 3v peak to peak or a little less is won't ever get down to 0v at the output of the IV opamp. Once you get down close to zero volts the opamp internal output stage will be in the cross over region and distortion should increase. Maybe AD797 has less cross over distortion, don't know?

Last edited by Markw4; Yesterday at 09:51 AM.
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Old Yesterday, 03:26 PM   #2783
Markw4 is online now Markw4  United States
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Join Date: Jul 2016
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@terry22
Sorry for the very brief reply last night. You are very welcome for the instructions, of course!

I notice you did say you would need help, and that is understandable. Towards the end of the instructions the pictures get very hard to make out how some of the components are arranged, like where some caps or resistors are soldered to ground. Actually, it doesn't matter exactly where they are soldered to ground for our purposes here, but still, it is hard to see from the pictures how I did some of it. Anyway, I assume that may be an area where you need help or perhaps some clarification about what to do.

If I guessed wrong and there are other things that need clarification, that's fine too. I am here to help and can respond to questions whenever you have them.

NOTE: On a slightly different topic, I am trying to figure out how to make it seem more attractive or easier to lift the I2C pins and hack into control of the dac registers. Not sure what the reason is most people don't seem to want to go there. If it is the risks of pin lifting, that would be one reason. If it is learning Arduino programming, that would be another reason. Maybe understanding the data sheet could be reason.

I would like some feedback from people telling me the main reason they don't do that part of the modding. What is the main one or two reasons why not?
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Old Yesterday, 05:43 PM   #2784
longimanus is offline longimanus
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Join Date: Nov 2016
I have recently received my v1.07 board and played a little with it but a more serious attention to modding will be given in the following weeks. I have left an open conceptual discussion on the design of the output stage and intend to continue it, with practical implications, hopefully, as it still seems to be of interest. But for now I have only questions.
Of these three cheap XMOS boards 1, 2, 3 which one would be considered most appropriate for this DAC, assuming one wants to push things to the possible limit. 1 and 3 have the same pinout, I believe, with 2 having the SPDIF pin in a strange position. I am quite unsure if the Altera changes things for good (there is one review somewhere about power problems and heating issues). All have the F0-F3 outputs, none seems to support DSD512 or PCM>384K (or maybe I'm wrong?).
Next question concerns the AK4137 boars and is, I guess, for Markw4, as he seems to be the only one who had tried the two versions, and DRONE7 and has 3 sub-questions. A. Do we lose something besides the SPDIF and TOSLINK inputs and the more convenient XMOS board montage if we choose the cheap board? Even a small detail? B. In the description of the cheaper board there is this sentence: "When the input PCM signal is lower than 176.4K, it can output DSD64." Same thing in the datasheet. Yet we have two examples of successful 16/44,1 to DSD256. So I should take it as granted it will work, right? C. Does someone expect that the 49MHz crystal in the 768KHz version will have significantly worse characteristics than the 24,xMHz one?
Simple yes or no answers will suffice. Thanks!

Last edited by longimanus; Yesterday at 05:51 PM.
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Old Yesterday, 07:52 PM   #2785
Markw4 is online now Markw4  United States
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Very hard to answer detailed questions about XMOS boards. In part it depends which driver they use. To get full features with DSD requires the specially licensed driver that I believe is keyed to the device's USB id numbers. There may also be Chinese clones of Amanero boards which I don't know which chips they use. For the best guaranteed features either go with the original Amanero brand, or the XMOS brand that offers licensed drivers. For diyinhk boards, there is an extra fee for the full feature driver.

However, it doesn't matter to me. I convert all content to upsampled DSD. The content I am starting out with is not native DSD to begin with.

Anyway the functional differences between boards that I am aware of include, 1) drivers that support native DSD, 2) clocks that support 768k but do not support 48k (you have to make a choice), and 3) whether or not a SPDIF output is available (regardless of the pin, which can always be patched).

So, I would say look at the ads for those things and make your choice for what you want.
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Old Yesterday, 10:27 PM   #2786
Markw4 is online now Markw4  United States
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Quote:
Originally Posted by longimanus View Post
Next question concerns the AK4137 boars and is, I guess, for Markw4, as he seems to be the only one who had tried the two versions, and DRONE7 and has 3 sub-questions. A. Do we lose something besides the SPDIF and TOSLINK inputs and the more convenient XMOS board montage if we choose the cheap board? Even a small detail? B. In the description of the cheaper board there is this sentence: "When the input PCM signal is lower than 176.4K, it can output DSD64." Same thing in the datasheet. Yet we have two examples of successful 16/44,1 to DSD256. So I should take it as granted it will work, right? C. Does someone expect that the 49MHz crystal in the 768KHz version will have significantly worse characteristics than the 24,xMHz one?
Simple yes or no answers will suffice. Thanks!
Regarding the AK4137 boards, the ones I have are the same except TOSLINK and SPDIF missing on the cheap one, and one other difference. The more expensive board has a way to set it for compatibility with XMOS or Amanero boards, but I don't know what that changes. It also has a menu to tell it if the clocks on the board are high or low frequency versions (the low version is for AKM dacs, I think. They are half of the usual clock frequencies). For most or all practical purposes, I think the difference is the SPDIF and TOSLINK. Not sure about differences in the abilities or limitations of either one to auto-detect incoming audio format without any manual selection required. In other words, I haven't tested them for all incoming audio formats, so I don't know. I suspect they both support whatever the AK4137 is capable of.

Regarding which incoming sample rates can be converted to what DSD sample rates, I think that has to with it only wanting to upsample, to some extent. So for example, the lowest DSD output sample rate cannot be used to play much higher sample rate PCM input. However, all that probably doesn't matter because if using a 100MHz clock with the dac, the 11.2MHz DSD sounds the best so it should be used for everything.

Also, the AK4137 filter choices sound most 'right' and the best if harmonic distortion compensation and DPLL bandwith settings in the dac registers have been optimized. Otherwise, the sound may seem a bit brighter than it should due to remaining harmonic distortion products at higher frequencies. (if the bass is weak, a slightly different symptom, that is most often a problem with AVCC.)


EDIT: Earlier I asked for feedback as to why very few people seem to go through with setting up an Arduino to access dac registers. Still would like to know what the main one or two reasons are for not going there? Does the pin lifting to access I2C signal seem too risky? Is Arduino programming considered too hard? Does the Arduino shield board look too complicated to build? Cost of parts? What? Thx!

Last edited by Markw4; Yesterday at 10:29 PM.
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Old Today, 12:13 AM   #2787
Mikett is offline Mikett  Canada
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Quote:
Originally Posted by eziitis View Post
this kind of: NEW ES9028 ES9028PRO DAC DSD decoder high quality assembled board for hifi audio | eBay

apparently the chip sources/sinks 16mA.
in i/v it had 560R FB, which caused clipping at 0dB, so after changing it to 250R, I got 4V p-p after i/v, what then is in the linear region for LME49720 i think.
obviously the stock LPF should be changed as well, with Fc about 50kHZ for DSD.
sound is improved of course, more relaxed without "shattering glass" tint.
what is puzzling, only AD797 gave clean spectrum, for all others 2nd harmonic present.

and I was wondering how then the TH mod ES9038q2m sounds now?
Look carefully at the open loop gain of LME49720 and what range they are specified for. . Some other op amps have their open loop gain specified as a function of rail voltage. There is a reason why the first portion of the IV is run higher. It is to optimise the noise performance. The second stage will take it back to line levels. In the first stage one needs to carefully choose the op amp to maintain low distortion at 0dB as you've discovered. Then for the Pro chips, the best op amps are running close to the edge. In my prior post, I will be running at 17V rails rather than 15 for these reasons and my choice sits with the OPA161x series. Their output stage appears to be more linear at the extremes of voltage swing. Can't see a 9038pro doing well, with similar op amps much less LME49720. They will have a hard time swinging the current as well. The 9028pro appears to be at the limit of commonly available popular op amps.
The 9038SQM is running at a fraction of the Pro chips current being a mobile oriented chip. Here the current is not a critical issue but still I would think the noise model holds as well.

Last edited by Mikett; Today at 12:15 AM.
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Old Today, 01:33 AM   #2788
Markw4 is online now Markw4  United States
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Join Date: Jul 2016
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Quote:
Originally Posted by Mikett View Post
Look carefully at...would think the noise model holds as well.
Somehow one just kind of senses that Mike must have been the mechanical engineer that he was, prior to retirement. Might have been something close, say maybe civil enginer, but just can't have been electrical. However, we wish him the best with his project. Please let us know how it keeps coming along, Mike. I'm already subscribed to his other thread, Moving from 9038Q2M to a 9028Pro board

By the way, I am not aware of a chip with the part number, ES9038SQM. Think there is an ES9038Q2M though.

Last edited by Markw4; Today at 01:36 AM.
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Old Today, 07:56 AM   #2789
terry22 is offline terry22
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Join Date: May 2017
Quote:
Originally Posted by Markw4 View Post
NOTE: On a slightly different topic, I am trying to figure out how to make it seem more attractive or easier to lift the I2C pins and hack into control of the dac registers. Not sure what the reason is most people don't seem to want to go there. If it is the risks of pin lifting, that would be one reason. If it is learning Arduino programming, that would be another reason. Maybe understanding the data sheet could be reason.

I would like some feedback from people telling me the main reason they don't do that part of the modding. What is the main one or two reasons why not?
Hi Mark,
For me Arduino programming is not an issue.
It's more the pin lifting problem. it is a very small piece...
But i am very interested into hacking the chip :-)
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