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China ES9018PRO ES9028PRO 9038PRO mods&upgrades
China ES9018PRO ES9028PRO 9038PRO mods&upgrades
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Old 1st January 2019, 05:33 AM   #1
idir is offline idir  Poland
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Default China ES9018PRO ES9028PRO 9038PRO mods&upgrades

This thread is to put together all possible modification to improve SQ of that cheap DAC board.
Schematic:
ES9018新.pdf
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Old 1st January 2019, 10:28 AM   #2
idir is offline idir  Poland
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Default pictures of the boa

20170404_131739854_iOS.jpg. DSC02430.JPG. DSC02433.JPG. DSC02435.JPG
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Old 1st January 2019, 03:37 PM   #3
phase is offline phase  United States
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That looks better than many of the other es boards I’ve seen, looks much more diy friendly anyways.
I have a similar ak4495 board that shares some of the regulators.
First thing I would do would be to straighten out the loads on the onboard regulators before getting wrapped up in any external regulation schemes. The differences between what is provided and some of the super low noise regulators will be washed out in the application.

The LT1963 will work with an output capacitor that has an esr as low as .050 ohm, and the smaller ams1117 will work with capacitors that have an esr as low as .300 ohm.
What I have found to work well is to use something that has values like this with each part.
The Sanyo Oscon 47uf is going to be more well suited to being placed after the LT regulator than after the smaller ams part.
The ams1117 I have found will work well with a 100uf, 16v, starndard electrolytic such as a bc 037 for example, or the Nichicon VX.

That along with putting a .01uf COG on the clock for decoupling will make a nice difference, and there is still likely much to be gained from the output stage as well.
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Old 1st January 2019, 04:41 PM   #4
idir is offline idir  Poland
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Phase, thank you for your input. Could you please elaborate on how to "straighten out the loads on the onboard regulators"
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Old 1st January 2019, 06:02 PM   #5
Markw4 is offline Markw4  United States
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If that nice looking black board is the one I recall, I rejected it because both left and right AVCC supply traces were tied together somewhere in a multilayer board and impossible to separate.
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Old 1st January 2019, 07:17 PM   #6
phase is offline phase  United States
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The regulators are made such that they can only be stable, and provide the advertised specifications for noise and transient response by having a certain range of output capacitor specs.
This is, in this case, not necessarily determined by the first number, or UF value of the part, but by the esr, or resistive component that these parts all have. Often they are described as impedance curves, and are really what makes one type of part, or dielectric more appropriate for the different uses that we deal with in audio, or anything else really.

Kind of like tires on vehicles; a tractor tire might fit onto a Porsche rim, and same with the car tire on the tractor rim but isn’t the ideal way.

The common commercial regulators are usually meant for mass produced consumer goods that will be using lower cost, and ready for automated assembly types of parts, like ceramic, and tantalum, as are mentioned in many of the data sheets. Most parts have been made by several manufacturers, and by digging, you can usually find more information on the various components.
The same regulators on one of my projects has responded very well to the changes mentioned above, after I had zealously applied a bit too much in the way of low esr parts to the circuits. This included the oscon types as well, which I am finding only have limited uses in digital audio. They seem to be great as long as they don’t exceed the minimum esr of the regulators, or resonate with the smaller ceramic parts that are required as local decoupling.

After the on board power supply is improved, a snubber circuit can be added to the diode bridge for a great bang for the buck, global improvement. I always make sure and put a .1uf polypropylene X type of capacitor across the incoming power as well on any line level gear.
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Old 2nd January 2019, 10:08 AM   #7
idir is offline idir  Poland
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Default PCB uncovered

pcb-all_s.jpg
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Old 2nd January 2019, 02:28 PM   #8
Mikett is offline Mikett  Canada
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Quote:
Originally Posted by idir View Post
Grounding layer appears to be missing on the PS have not checked the rest . Good job, uncovering the outer layers though.

Here is what I have done so far with mine and from there I changed the AD817 to an AD797 which sounds superior.
ES9038Q2M Board
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Old 2nd January 2019, 03:25 PM   #9
idir is offline idir  Poland
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Tbh I have no idea about the other layers. I got ahold of a faulty board with a short circuit between layers, so could use it for educational purpose.


So far I have upgraded the following:


- Clock changed to Crystek CCHD 950
- burson v6 opamps
- Changed Wima MKS capacitors to MKP.
- replaced counterfeit mika CDE capacitors with original CDE 1% 100 pF.
- fake Elna Silmic II are still there waiting to be replaced with originals.


IMG_20190102_165347.jpg
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Old 2nd January 2019, 06:33 PM   #10
phase is offline phase  United States
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I have had great results with using a combination of Siemens KS, or EMZ polystyrene along with the Wima FKP2. Looking at the circuit, I will place the polypropylene caps in series with the signal path, and the polystyrene in the shunt positions to ground.
This has given a nice balance of punchy bass, with smooth airy treble, at least in my experience/opinion.

Those 100pf can be swapped out for better parts too...

I didn’t see any local bypass on the op amps when I looked at the boards, if you can, try .01uf film caps under the sockets, directly on the pins.
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