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ES9038Q2M Board
ES9038Q2M Board
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Old 24th March 2018, 04:03 PM   #411
Markw4 is offline Markw4  United States
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Quote:
Originally Posted by terry22 View Post
Hi,
I just received the LT3045 regulator in 3.3v.
Does some of you may check the attached picture and tell me if it is the right way to connect it?
That looks right. Just be careful that nothing on the new regulator PCB touches anything on the Chinese DAC board where something might short out. The LT3045 PCB needs to be mounted in some way so something like that can't happen.

Also, try to be careful removing the old voltage regulator. if you have any leaded 60/40, or even better 63/37, rosin core solder, sometimes adding a little of that to original solder can make it easier to remove with solder wick or with a solder sucker. Solder wick is usually the method of choice for printed circuit boards.

Last edited by Markw4; 24th March 2018 at 04:09 PM.
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Old 24th March 2018, 07:09 PM   #412
terry22 is offline terry22
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thank you for your help.
Do you think that the lt3045 need a heatsink?
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Old 24th March 2018, 09:14 PM   #413
Markw4 is offline Markw4  United States
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Couldn't hurt, but I doubt it would get too hot very fast if you tried it without one just to see how hot it does get. If you can't keep your finger on it, that's hot enough and you would probably want to have a heatsink.
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Old 25th March 2018, 10:10 AM   #414
vacuphile is offline vacuphile  Netherlands
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Quote:
Originally Posted by DPH View Post
In either case, it clearly seems like your I/V isn't the culprit in the rather mediocre performance but the 9038 board, seeing as Victor is still getting better all-in performance (~-115 dB on the 3rd harmonic at 0 dBfs).

Still nice knowing these guys perform better in current mode. Also, the measurements are appreciated!
I found both 9018 and 9038 boards to perform at comparable levels after modification, using the same break out board with LM4592, using balanced current mode operation (pretty along much JensH's board).

The ES9018 board is slightly easier to modify, because through the removal of some tth caps, you can solder wires using their holes, in stead of soldering them on surface mount pads. Not a big deal though.

Furthermore, I found that the ES9038 board has higher than necessary distortion because of insufficient decoupling of the analog supply rail to the DAC. Mounting a largish cap underneath the board, using the pins that protrude from the board of the 47uF caps mounted above, brings significant improvements. You can improve low end distortion reduction by about 8dB, just by mounting 2200uF caps at this location.

The ES9018 board does not have this problem.
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Old 25th March 2018, 10:20 AM   #415
JensH is offline JensH  Denmark
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ES9038Q2M Board
Interesting find about the insufficient decoupling. I will try to add some decoupling and measure again. It will have to wait until next weekend though.
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Old 25th March 2018, 10:46 AM   #416
vacuphile is offline vacuphile  Netherlands
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Hi Jens,

For good measure, I include two pictures of the board before and after the modifications.

unmod9038.jpg

mod9038.jpg

I may feel inclined today to see if there is an optimum point for loading this chip. Perhaps some hybrid between voltage and current mode is the way to get better performance out of this board. Otherwise, the ES9018 board is just as good at 1/3rd of the price.

Note 1: opamp rolling in the standard board does not provide any measurable differences between the NE5532 the board comes with standard. I happen to believe this translates to no audible differences.

Note 2: why all this effort, shouldn't I get a life? As to the latter question, yes, please . As to the former: I ordered a nanoshark and now need four DAC boards to get some sound out. I have a PCM1794 board on it's way and will decide after investigating it. For the moment, the ES9018 board seems to be the better choice.

Note 3: I just went through the whole thread and concur with Peterma that unmodified, the 9038 board sounds somewhat harsh. Changing opamps didn't change that, but I may have been influenced by the measurements, which show no differences.
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Old 25th March 2018, 11:46 AM   #417
cdsgames is offline cdsgames  Canada
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Quote:
Originally Posted by vacuphile View Post
I found both 9018 and 9038 boards to perform at comparable levels after modification, using the same break out board with LM4592, using balanced current mode operation (pretty along much JensH's board).

The ES9018 board is slightly easier to modify, because through the removal of some tth caps, you can solder wires using their holes, in stead of soldering them on surface mount pads. Not a big deal though.

Furthermore, I found that the ES9038 board has higher than necessary distortion because of insufficient decoupling of the analog supply rail to the DAC. Mounting a largish cap underneath the board, using the pins that protrude from the board of the 47uF caps mounted above, brings significant improvements. You can improve low end distortion reduction by about 8dB, just by mounting 2200uF caps at this location.

The ES9018 board does not have this problem.
This is also our findings. You need extreme decoupling on the analog stage . We chose film capacitors (3) + 0.3F caps on each L and R analog stages. Big difference , especially for low frequency. Bass is incredible .
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Old 25th March 2018, 11:55 AM   #418
vacuphile is offline vacuphile  Netherlands
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Hi Cdsgames, do you mean decoupling of the opamp, or the DAC-chip itself? It is the DAC-chip decoupling I was referring to. For this, you need more than you can realistically expect from a film cap, 2200 uF or thereabouts.
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Old 25th March 2018, 12:03 PM   #419
Markw4 is offline Markw4  United States
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Not surprising about the decoupling if you look at the ESS downloads page: ESS Technology :: Downloads The "Maximizing DAC Performance..." document has a diagram on page 4 showing the recommended AVCC power conditioning circuit, along with a table of recommended op amps. ESS recommends separate AVCC power conditioning for left and right channels in order to help minimize any cross-talk.

To change the subject a little for anyone perhaps interested in further modifications, all I did with my particular Chinese DAC was generally clean up the power, use recommended AVCC conditioning, use differentially summed IV circuits similar to ESS recommendations, and install an ultra-low-jitter clock oscillator module.

In addition to changes to the DAC board itself, the board is powered from one of Jan Didden's silent switcher +-15v supplies, there is an external LME49600 headphone amp, and also an external hardware SRC. One problem I found with the silent switcher is that it can pass some input noise to the output, so I supply it with clean +5v input power. Don't want to power it from an active USB hub.

The hardware SRC allows best performance with the slow-roll off minimum-phase reconstruction filter. If anyone wants to see what that sounds like there are some wav file examples here: DBX that have been software upsampled, or not. To me, the 24/96 upsampled CD rip sounds quite a bit better than the 16/44 version, especially with J3 installed on 1.06 version Chinese DAC to select the slow filter.

***EDIT: If listening on a Windows PC, you may want to be sure the shared sound output is set the the sample rate and bit-depth you want to play back, or Windows will perform real-time SRC on your audio stream making it sound worse than it should. I will post a screenshot below showing how Windows sound may be configured.

The headphone amp started out as one of these ebay cheapies: 1PCS LME49720NA+LME49600 headphone amplifier KIT | eBay which didn't sound that great given the weird power capacitor layout and low-ish feedback. I hacked mine by adding tantalum and ceramic decoupling caps at each IC, adding a copper tape foil ground plane, and mounting feedback and input resistors in the air above the PCB surface. Also, connected the LME49600 output pins in the air to avoid the long traces that ended up under my ground plane and also running next to the strange power distribution traces. The final circuit is the same as one of the LME40600 datasheet examples, with no stability problems, and pristine sound quality.

Addition of the headphone amp ends up making the completed project quite similar in sound quality to the Benchmark DAC-3 here, although without the number input options and remote control feature of the DAC-3.

I couldn't be happier with the result so far, but not quite done. Need some kind of unified power supply and case to put everything in. Also, still looking at adding USB input and maybe some other features. When it is done, I promised it to my son so he can have something good for mixing songs he is working on.
Attached Images
File Type: jpg WinSoundConfig.jpg (67.1 KB, 552 views)

Last edited by Markw4; 25th March 2018 at 12:29 PM.
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Old 25th March 2018, 06:26 PM   #420
vacuphile is offline vacuphile  Netherlands
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Update & nice to know.

The ES9038 apparently doesn't like to push against a zero Ohm load, but prefers a bit of resistance. I first scanned from 0-500 Ohm with a pot meter, and everything larger than 30 Ohms or so made things worse, but below it, there was considerable improvement possible.

I went down from 10 Ohms to 2.7 (in series with both legs of the DAC output on one channel), and distortion continued to improve:

BY ALMOST 6 dB (above 200 Hz and as compared to a 0 Ohm load).

Then I soldered in 1.2 Ohm resistors to go even further down. However, when I wanted to measure the results, the board froze on me. Both DSD and Lock leds light up at the same time and that will be the end of this experiment.

Curious to find out if the same improvement can be made with the 9018 board in this way. That would really make it spectacular for the price.
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