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ES9038Q2M Board
ES9038Q2M Board
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Old 18th October 2018, 06:14 PM   #3001
dv187736 is offline dv187736
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Join Date: Oct 2015
Quote:
Originally Posted by Markw4 View Post
Hi,
Good to hear back that the dac is now working. J3 rather than J2 only means that the firmware was a little different when your's was made.

By the way, the ES9038Q2M is still the same, which means you could mod the dac you have into being a very, very good one as we like to do here.
Mark,
The DAC board says ver. 1.04. I followed just a couple of the mods suggested here such as
- changing the capacitors (2) near the DAC chip to Panasonic 390mf,
- same for the caps near the OpAmp,
- replacing the Am117(?) 3.3v regulator with a discrete one I bought in eBay,
- did opamp rolling ending up with Muses01.
PSU is linear low noise also from eBay. Source player is an old MacBook. I use the Halide Bridge cable for USB-Spdif coax.

It really sounds fantastic on my system, that is for my ear, compared to my Peachtree DAC-it X, and two diy DAC I assembled from Chinese boards bought from eBay (ES9018K2M and ES9028Q2M).

Iím not sure I can implement the more difficult mods suggested and the one currently being discussed. But still looking for opportunities to improve.
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Old 19th October 2018, 05:14 PM   #3002
Markw4 is online now Markw4  United States
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Quote:
Originally Posted by dv187736 View Post
Iím not sure I can implement the more difficult mods suggested and the one currently being discussed. But still looking for opportunities to improve.
Not sure what you would consider to be a more difficult mod? Serge put up a pdf for swapping out the clock in his thread and I see some relative beginners were able to follow it and get the dac working with the new clock.

Seems to me anyone who can do that should probably be able to do most mods. The clock is, after all, an SMD part even if not a small one.

It does matter to have a temperature controlled solder iron and multiple sized tips for it, along with some small hand tools. Maybe a head-mounted magnifier of some kind, if like me.

A lot of the rest of it is just confidence that comes from practice. The small stuff can look much harder than it is. Only way to find out is to try it. There are some SMD practice kits available and some youtube videos with helpful advice. May as well give it a try, SMD is a big part of modern electronics and much of it is quite doable at home.
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Old 19th October 2018, 08:09 PM   #3003
MrSlim is offline MrSlim  Canada
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Default Through Hole AVCC and IV-Output Schematics

I've revised the AVCC schematic to show C8-9 as either Electrolytic or Film, and the board layout will include footprint's for both.

I've also added optional balanced outputs to the IV stage. R50-53 are jumpers that can be left out if the balanced outputs are not required. These jumpers reduce the amount of non-powered wiring on the board that could become antennae for external noise pickup.

Both Sheets of the BOM have been updated, as well as the Combined sheet.
Attached Images
File Type: png ESS9038Q2M_AVCC_V03.png (68.6 KB, 1186 views)
File Type: png ESS9038Q2M_IV_Output-V02.png (107.7 KB, 1029 views)
Attached Files
File Type: zip bom OutputStage-V03.zip (15.7 KB, 113 views)
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Old 19th October 2018, 08:24 PM   #3004
Markw4 is online now Markw4  United States
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MrSlim,

Thank you so much, sir. However, may I request to please revise the balanced outputs to add the circuitry shown below following each unbalanced output, if a balanced option is desired?

Also, not quite clear on why connectors are shown for the inputs, since it is strongly preferred to tie the ground planes together through a continuous bond.
This would be the case for both AVCC and the output stage. Perhaps more critically so for AVCC which needs to be as close to the dac pins as possible with as low a source impedance as reasonably possible.

EDITx: This has already been edited quite a bit, but I would like to add that I include 1,000uf electrolytics in parallel with 1uf film caps at the +-15v power entry point on the output stage board. I tie the AVCC board to the output board with short length 18 gauge wires for +-15v to the output board power entry filter caps.
Attached Images
File Type: gif Balanced Out.gif (3.4 KB, 930 views)

Last edited by Markw4; 19th October 2018 at 08:53 PM.
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Old 19th October 2018, 08:52 PM   #3005
Markw4 is online now Markw4  United States
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Somewhere or other I would also like to include that I use local 3.3v regulators, LT1763, for clock and VCCA. In part that is to help isolate them from digital noise from the MCU as recommended by ESS.

In addition, since I use an external +5v supply to power all three 3.3v regulators on the dac board, the ground return to the 5v supply is taken from the digital end of the dac board. The idea is to help keep digital ground currents from flowing in the analog sections of the dac as much as possible. +-15 and +5v power supply grounds are only tied together at the dac board.
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Old 19th October 2018, 09:47 PM   #3006
Markw4 is online now Markw4  United States
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Pulled the dac out of the test box to work on the quality of connections between AK4137 and ES9038Q2M. Trying to get DPLL bandwidth lower requires low connector noise. Will try soldering ribbon cable at AK4137 end, and more connector ground pins at dac I2S input.

Anyway, took the opportunity to take some pics showing the test board and the current state of the dac board including the LT1763 3.3v regulators for clock and VCCA.
Attached Images
File Type: jpg TH_Test11.jpg (658.0 KB, 937 views)
File Type: jpg TH_Top11.jpg (515.6 KB, 891 views)
File Type: jpg TH_LT1763.jpg (154.0 KB, 292 views)
File Type: jpg TH_LT1763-a.jpg (163.5 KB, 270 views)
File Type: jpg TH_LT1763-b.jpg (167.2 KB, 269 views)
File Type: jpg TH_LT1763end.jpg (97.3 KB, 242 views)

Last edited by Markw4; 19th October 2018 at 09:50 PM.
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Old 19th October 2018, 10:37 PM   #3007
Markw4 is online now Markw4  United States
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Quote:
Originally Posted by MrSlim View Post
Both Sheets of the BOM have been updated, as well as the Combined sheet.
Just noticed BOM item 6 shows both 220pf and 220nf. The nf abbreviation should be corrected to pf. Thanks!

EDIT: Also noticed in BOM for AVCC, there are no 10uf aluminum electrolytic. Instead there are five 10uf tantalum caps. The 10uf tantalum caps should be quantity 2, for opamp power decoupling only. 10uf filter caps for 3.3v AVCC and for Vref should be aluminum electrolytic, because tantalum caps are too noisy for that use. So, that would be quantity 3, 10uf aluminum electrolytic (low esr wouldn't hurt but probably not necessary here).

Last edited by Markw4; 19th October 2018 at 10:48 PM.
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Old 19th October 2018, 11:01 PM   #3008
Terry Demol is offline Terry Demol  Australia
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Quote:
Originally Posted by Markw4 View Post
MrSlim,

Thank you so much, sir. However, may I request to please revise the balanced outputs to add the circuitry shown below following each unbalanced output, if a balanced option is desired?
WRT revised arrangement, 33k will generate a lot of noise. Johnson noise alone will be around 33 nV/rt Hz then add current noise of opamp into
33k/2.

T
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Old 19th October 2018, 11:05 PM   #3009
Markw4 is online now Markw4  United States
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Hi Terry,
Agreed. That schematic was copied from somewhere else. Makes sense to reduce those resistors to something more reasonable. In case the balanced load impedance is very low, it might make sense for the resistors not be be too small though. Something like 4.7k would probably be okay. Signal to noise by that point should be pretty high anyway. If someone knows they won't be driving a very low impedance load they could make the resistors smaller too.
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Old 20th October 2018, 12:05 AM   #3010
dv187736 is offline dv187736
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Quote:
Originally Posted by Markw4 View Post
Not sure what you would consider to be a more difficult mod? Serge put up a pdf for swapping out the clock in his thread and I see some relative beginners were able to follow it and get the dac working with the new clock.

Seems to me anyone who can do that should probably be able to do most mods. The clock is, after all, an SMD part even if not a small one.
Mark,
I have not done any Smd soldering before, but yes perhaps it is time to try my hands on this. Iíll search for Sergeís pdf on the clock and understand what improvements are to be expected and how to install a new clock.

I read an article reviewing a recently released version 1.07 of this board. Apparently it is a much improved version. But I couldnít find it in eBay. Was thinking to reapply the mods including the new clock suggested.
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