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China ES9018PRO ES9028PRO 9038PRO mods&upgrades
China ES9018PRO ES9028PRO 9038PRO mods&upgrades
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Old 14th February 2019, 08:42 PM   #41
jlw is offline jlw  United States
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@idir: Curious how you would describe the imperfections of this DAC.

To me this DAC handily beats all 9018-based DACs I have heard except for one.
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Old 15th February 2019, 10:20 AM   #42
idir is offline idir  Poland
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@jlw To me, this DAC performs slightly better than my HiFIberry on the Rpi. I feel that higher frequencies still sound a bit harsh, hopefully, this is only a matter of PSU. I Will replace all the power section on the board including regs and will share my findings and parts used here.
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Old 15th February 2019, 04:17 PM   #43
jlw is offline jlw  United States
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The power supply looks decently regulated to me. Are you able to measure PS noise at all? Or is it just an A-B comparison with another DAC leading you to think it's noisy?
My only suggestion is perhaps change out all 12 diodes to Schottky types but I doubt if you can hear a difference.
If your OpAmps can't take the current it will distort and give you a harsh sound.
Hence my suggestion to use 1622 on the XLR side and 1611 on the following RCA side.
Burson OpAmps sound good in most other applications but cant take high current and I already killed 2 with my old 1794 based DAC.
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Old 15th February 2019, 04:50 PM   #44
Markw4 is offline Markw4  United States
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Its not usually power supply noise so much that makes a dac sound harsh. It is power supply impedance over the entire range of audio frequencies up to 100kHz or so for the analog components. There are some different approaches to help with that including different kinds of electrolytic caps, sufficient number and sizes of film caps, or removal of most filter caps except X7R decoupling caps and use of fast shunt regulators, etc. The quickest easiest test to see if you can get its attention would be to solder some film caps together in parallel and add them to each of the +-15v rails for the opamps. I have written elsewhere about using Wima mks4 in the following values from each of the +-15v rails to ground: 10+10+22+33+33 (all values in uf, and, yes, I know its a lot of film caps). So far everyone who has tried the film caps has found immediate sound quality improvement, even if using a total uf value quite a bit less than I did.

AVCC power quality matters a whole lot too for Sabre chips. For that, I would avoid LT304x regulators which most people seem to sound 'flat and lifeless' in that application. ADM7150 or ADM7154 are used for some good dacs. Twisted Pear sells some AVCC dual regulators and single ADM7150 regulators called Trident-SR, but the board you have has the AVCC pins for both channels shorted together, IIRC, so only a single good AVCC supply is needed and can be used. If Trident-SR isn't too expensive you might try that. Or, they still have some of older Trident (pre-SR version) AVCC regulators for about $40. Probably way better sounding that what you have now.

Last edited by Markw4; 15th February 2019 at 04:57 PM.
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Old 15th February 2019, 10:41 PM   #45
jlw is offline jlw  United States
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Index of /9038
@markw4 thanks for the detailed info. Looks like if I were to make PS mods I need to pull the thing out of chassis.

Anyway I am very happy with the sound. Handily beats a MSRP$10,000 DAC based on the 9018.

@idir The caps may not be fake, different outer coat I guess?

http://ec2.snoopy.org/9038/IMG_6214.JPG


http://ec2.snoopy.org/9038/IMG_6215.JPG
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Old 15th February 2019, 11:36 PM   #46
KCHANG is offline KCHANG  United States
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I have both the 9028Pro and 9038pro DAC boards. To my ears both boards sound nicer than Topping D50 and SMSL D9. There is some kind of immediacy of the sound of the 9028/38Pro boards that I did not get from the D50 or D9.

Not sure whether the 9038Pro board is a significant improvement over the 9028Pro board. They sound very similar to me. Opamp rolling and even adding different bypass caps to the +-15 rails seem to make more discernable differences than the differences between the two DAC chips.


Kurt

Last edited by KCHANG; 15th February 2019 at 11:43 PM.
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Old 16th February 2019, 01:10 AM   #47
jlw is offline jlw  United States
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@idir recapping the whole thing does make a difference.
I am using Nichicon KS for the pre-regulation caps
KW for various 220uF and 10uF
Elna RFS 25V 47uF for all 47uF positions.
So whether the original caps are fake or otherwise is still a mystery.

@Kchang agree with the OpAmp rolling. The trusty old OPA627s need not apply here with the 9038.
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Old 16th February 2019, 05:39 AM   #48
jlw is offline jlw  United States
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@markw4 the regulators I see on the board itself are just a 337BT 317T and a 7805. So its very basic run of the mill stuff. I see your point of replacing the caps right at the output of the 15V regulators to film for starters. Real estate is an issue here IMO.
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Old 16th February 2019, 05:57 AM   #49
Markw4 is offline Markw4  United States
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I don't know about replacing the existing caps depending on the their values as they may be helping some at LF, but you might disconnect the outputs of the +-15v supply if possible, and run them a little ways to where you can put a set of parallel film caps, then run the output of that back to the board 15v rails. If you use thick enough wires and the distance isn't too long it would probably work okay. If not, you could always put it back the way it was.

Not having a board to look at myself, not sure what may be possible. Also, if I'm not mistaken, the board you have looks a lot like the one Mikett opened a thread on modding several months ago. I think he may have done some work to improve the power supplies, but don't know specifics.
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Old 16th February 2019, 07:05 AM   #50
jlw is offline jlw  United States
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@markw4 with my high voltage projects i always find ways to mount my trusty Panasonic 500V 50uF films that look like WIMAs andmount on inner wall. Here the need to use 220uF 50V at the regulator output makes for a challenging size esp given the miniature chassis. Anyway this DACin its current form handily kicks my Silbatone anyday w any type of music.
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