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ES9038Q2M Board
ES9038Q2M Board
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Old 6th December 2018, 03:24 PM   #3321
Markw4 is offline Markw4  United States
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Quote:
Originally Posted by laserscrape View Post
In normal circumstances these internal regulators would be receiving power from noisy SMPS, like a PC, but with the LT3045 these internal regulators are probably adding noise. there is multiple though, so im not sure if they are providing some isolation between different parts of the DAC chips.
Probably the local regulators do help with isolation of noise produced by different load devices on the board. My guess would be to keep them as is, or maybe improve them with better filter caps at each regulator if you think something like that might help.
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Old 6th December 2018, 05:12 PM   #3322
Markw4 is offline Markw4  United States
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Went ahead and ordered some more film caps so I can directly compare Katana and the modded dac once again. I could also see if even more film caps has any further effect on sound quality. It could be that more would be better, or maybe I already have more than enough and am wasting some. Be interesting to see.
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Old 6th December 2018, 06:38 PM   #3323
AlexJones is offline AlexJones  Ireland
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Hello Mark,

Just wondering. Is there a more comprehensive way to follow your exact build? I started reading this thread from the beginning but it's a huge amount of information. I know you mentioned further back that you were planning something like that?
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Old 6th December 2018, 07:07 PM   #3324
Markw4 is offline Markw4  United States
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Quote:
Originally Posted by AlexJones View Post
Just wondering. Is there a more comprehensive way to follow your exact build?
Hi Alex,
Yes, you might try looking at post #3306 here:
ES9038Q2M Board
At least hopefully that will help you get up to speed more directly. The most recent things I have been working on since my last summary might require browsing through. If anything isn't clear, please ask and I will try to provide what you need.

The area I am working in right now has just undergone a few test mods to see what will happen. Picture attached below.

I am testing a potential upgrade of some decoupling caps, and moved some wiring around associated with feeding power to the caps. Also, added a loop of bare wire on the right as a ground test point, and grounded a currently unused power trace. This stuff may not mean much now, but eventually I hope it will help improve performance.
Attached Images
File Type: jpg Modded Area.jpg (373.6 KB, 264 views)

Last edited by Markw4; 6th December 2018 at 07:14 PM.
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Old 6th December 2018, 07:22 PM   #3325
AlexJones is offline AlexJones  Ireland
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Ah Mark that's amazing. Thank you so much. I'll delve through that over the weekend. Cheers!
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Old 7th December 2018, 01:41 AM   #3326
redjr is offline redjr  United States
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Quote:
Originally Posted by Markw4 View Post
redjr,
Do you by any chance have custom page lengths set for the forum? I ask because that can cause post links to fail. Post #3301 is on page 331 here.
The post numbers should be (reverse order):
2792
2873
1412
780
716

Just noticed bit more in post #2862
ES9038Q2M Board
If I do, it wasn't intentional. Where would I check and change it?
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Old 7th December 2018, 01:47 AM   #3327
Markw4 is offline Markw4  United States
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Quote:
Originally Posted by redjr View Post
Where would I check and change it?
It would be in your personal preferences somewhere. I don't have access to that myself because it normally requires 'donation' user account perquisites.

To check if your page numbers are normal, the default is 10 posts per page. This post is #3327 on page 333, and the link to it is: ES9038Q2M Board
The last post on this page will be #3330, etc.

Last edited by Markw4; 7th December 2018 at 01:50 AM.
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Old 7th December 2018, 03:59 PM   #3328
Greg Stewart is offline Greg Stewart  United States
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ES9038Q2M Board
It is in the 'Edit Options' page under the 'Your Control Panel' page, the 'Thread Display Options' section. I have mine set to 50 posts per page, which means a lot less clicking when going through long (and informative) threads such as this. BUT I know that DIY Audio post links I provide don't work for others and ones they provide don't work for me, so I always just provide the post number in the thread.

Greg in Mississippi
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Old 8th December 2018, 02:18 AM   #3329
redjr is offline redjr  United States
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Thanks guys. Mine was set to 50 posts/page. I think I changed it years ago.
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Old 10th December 2018, 12:52 AM   #3330
Markw4 is offline Markw4  United States
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A small update on progress with the modded dac: I removed the high cost AK4137 board from the test setup and installed a new low cost AK4137 with the optional 768kHz PCM crystal option. It works fine at 768kHz, and this AK4137 board also includes a slave mode that high cost board does not have. It looks like AK4137 itself is capable of operating as a PCM slave to the dac clock signals, but not as a DSD slave. That might be okay. It raises the possibility of tweaking ES9038Q2M registers to make it run as master. Haven't looked at doing it any any detail yet. Since we are using 100MHz clocks, possibly we might have to use Clock_Gear register setting to divide that down to run the dac chip at 25MHz. The AK4137 could probably slave at the corresponding sample rate, although it would be non-standard. That might not be a bad thing actually. In that mode it might work a lot more like Katana, although a divided 100MHz clock might not be as low jitter as an undivided 24MHz clock. At least we could try it out and it might open the possibility of having more than one clock for ES9038Q2M, kind of similar to what Katana has.

The other thing is I still don't have a real good handle on how to get DPLL stable as I would like. I did leave it overnight last night and just checked it again now. It has been staying stable at 4 out of 10. It runs at 3 too, although doesn't sound as good as 4. At a setting of 2 it is not stable without some retuning.

Right now I am pushing on a place on the dac PCB (with a plastic stick held in a dial indicator holder) that got DPLL to stabilize where it is. No ferrites in there at this point. It looks like most of the tuning of DPLL stability is by flexing the board a little, but exactly how it works is rather confounding. Ferrites when they are in there seem to mostly help keep RF fields more contained. It's hard to shield effectively in there, but making it easy for EM flux to stay in the region seems to be having a similar end benefit.

I did try rerouting some power wires and putting in a few decoupling caps of known quality. Didn't really fix it, but it may be a little more stable when it does work. Probably will change out the remaining old decoupling caps next time I have the board out.

In the meantime I am getting the 1st modded dac board ready to go back in the test box to see if it behaves the same as the 2nd modded dac with respect to DPLL stability. Just changed the I2S pin header to gold. I already confirmed that both types of AK4137 boards seem to be about the same with respect to DPLL stability.

It strikes me that one possibility might be that with some flexing the dac board its clocking might be slightly pulled in frequency with respect to the 22HMz clock on the AK4137 board. It could be that when they are kind of synchronized, that DPLL is more stable. Its might be something like two grandfather clocks in the same room, eventually they will tend to pull into some kind of synchronicity with each other due to coupled vibrations interacting to reinforce such a mode. With clocks it might be the EM fields and or some cable coupling between the boards. If something like that, I don't know that I will be able to do much with it other than let them stabilize together and try not to otherwise disturb them. I don't have any reason to believe that over-coupling them would necessarily help more if something like natural-synchronization is happening.

While the foregoing is pretty speculative at this point, the behavior of where to push on the dac board to tune DPLL stability doesn't seem to make much sense by itself. Sensitive spots seem to move around and pressure to flex the board tends to cause it to slowly 'give' and over-flex thus de-tuning it. Weird, seems to kind of sum it up. Maybe if I had a really good frequency counter I could test the idea, but I don't have anything like that probably as stable as the dac clocks are. Be nice to have something stable and repeatable down to .1Hz or so (sometimes DPLL instability is rather slow). Doesn't necessarily have to be all that accurate just to see some correlation between clock frequencies syncing together, if in fact they are.
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