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-   -   Build thread for ES9023 + JG Buffer boards (betatest) (http://www.diyaudio.com/forums/digital-line-level/232003-build-thread-es9023-jg-buffer-boards-betatest.html)

curryman 13th March 2013 10:01 PM

Build thread for ES9023 + JG Buffer boards (betatest)
 
I opened this thread for further discussion about my I2S input ES9023 + JG Filter Buffer boards.

Of course any general discussion about the detailed application (Cs, Rs, regs,...) of the ES9023 DAC chip is very welcome ;)

I'd like to start with my current findings after some first tests:

After initial setup of the board according to the actual "beta"BOM I did some first measurements (of course I also listened and really enjoyed music :D). Like others reported before there is some noise arround 1.5MHz especially at the NEG pin which could be reduced by moving the 2.2F MLCC directly to the pins of the DAC (on the board it is only a few mm away :eek:). Furthermore I found some modulation from the music signal on the NEG pin! I tried different Elcaps (220F Pana FC -> 470F Pana FR with lower ESR -> 22F Pana FR) and the lowest measured best (no listening test) so i'll probably stay with 22F.

I remember some discussion about removing the charge pump cap and implementing external NEG voltage, however the discussion stopped and no one posted results. Did anyone test this and can report his findings?

I also measured GND noise at several positions on the board and found it to be quite clean. However my scope is quite old and not the most sensitive on earth (5mV).

Another point is the "clipping resistor" at VREF pin. I could not measure any significant clipping and liked the sound without the R, however this might be personal taste. I'll definately leave this option for the next design.

Hope some will join this discussion so that everyone can benefit from our findings ;)

Best regards, Daniel

enjoybiking 14th March 2013 01:35 PM

I have been meaning to try a 50KR in series with ~200K POT wires as a variable R, on the Vref pin..., and I suppose a switch in series [close to the DAC] JUST for experimentation.
Then find some music laid down hot, certain female vocalists close to a mike can distort, for instance. I think the use of the pin could have other sonic impacts than just trying to prevent clipping -- I remember the day I took a UAE23 [MODDED with 3.6V and 100K there] to my Sister and Brother-in-law's -- as I seem to recall I left them 2x DACs, one with and one without. A jury of two preferred the R there in terms of other detail and staging... "your mileage may vary". So don't JUST think about clipping. Now, their system is unusual, that DAC signal would have been going immediately into a Yaqin CD2 cathode follower buffer.

Daniel do you know what V is on the NEG pin? I could get a regulator pretty fast and try it.

curryman 14th March 2013 02:14 PM

Quote:

Originally Posted by enjoybiking (Post 3410492)
I have been meaning to try a 50KR in series with ~200K POT wires as a variable R, on the Vref pin..., and I suppose a switch in series [close to the DAC] JUST for experimentation.
Then find some music laid down hot, certain female vocalists close to a mike can distort, for instance. I think the use of the pin could have other sonic impacts than just trying to prevent clipping -- I remember the day I took a UAE23 [MODDED with 3.6V and 100K there] to my Sister and Brother-in-law's -- as I seem to recall I left them 2x DACs, one with and one without. A jury of two preferred the R there in terms of other detail and staging... "your mileage may vary". So don't JUST think about clipping. Now, their system is unusual, that DAC signal would have been going immediately into a Yaqin CD2 cathode follower buffer.

As mentioned the SMD pads are available on the PCB so everyone can use it or leave it ;)

Quote:

Originally Posted by enjoybiking (Post 3410492)
Daniel do you know what V is on the NEG pin? I could get a regulator pretty fast and try it.

Errm, measure it :p

hint: should be similar to voltage at AVCC pin to generate 0V DC at the outputs ;)

luxury54 14th March 2013 02:55 PM

Hi Daniel,
I just received the boards from you today and they are great, professionally made and they look better than in pictures, thanks for making them available :)
I will start ordering parts and maybe next week receive them and in weekend solder them to the board; can't wait to hear the sound of the direct output compared to the J G buffer filter

great work

enjoybiking 14th March 2013 06:30 PM

Drum rolllll, and the answer is -3.4Vdc Es9023 NEG pin with me running the DAC at +3.6 but with cap choices not in the Curryman BOM [a modded HiFiMEDIY UAE23 DAC]

enjoybiking 15th March 2013 12:27 AM

I should add that to the degree it might matter, the above reading was with 100K to ground on ES9023 pin #6. Oppz, no, huge mistake, come to think of it, the -3.4 was across the pin#6 resistor, effectively, so, I have not measured the NEG pin YET, I was in a hurry :^| I will measure the NEG pin ASAP. I suspect the NEG will be more NEG, just a guess. Again, using a HifimeDIY UAE23 as the subject to take my readings from.

If the negative injection works to the NEG pin, I'm thinking something simple, either a negative ADJ regulator, or a -5V feeding loaded voltage divider: a POT or 2 R in series 32+68Ohms let's say? To ground. Cap middle to ground. This would only be to end up with less DAC noise, else why bother? What's one more regulator when we use them like salt? No Charge-pump noise? no CP cap{s}?

I have tried 330uF 25V Panasonic FM caps in the beta-board's various larger cap holes 5mm, they fit fine. The Test/Beta BOM should not be taken as Daniel's latest best test results so DO read what he has said, I hope all the comments have made it to the build-thread but maybe not. I know how anxious people get, even me... do not buy all the parts and assume the beta anything is where you want to be, meaning no offense to anyone, especially Daniel who was so brilliant to come up with this extension to the JG filter buffer. The BOM is a work-in-progress subject to changes. I LOVE THE ES9023 and think it's a diamond in the rough, we could easily get more out of it for performance than the designers intended or suggested.

curryman 15th March 2013 08:24 AM

Enjoybiking is correct, take the BOM as a starting point for your own experiments! This is a betatest and not a final design but I think thats clear to all participants ;)

swalter 15th March 2013 07:34 PM

Thanks Daniel for making that possible, all parts except the ES9023 arrived last week, they should hopefully arrive here next week. Can't wait to fiddle around with it :)
Stefan

enjoybiking 16th March 2013 04:10 AM

I have regulators coming to brute-force try and insert the -V in place of the charge-pump in the ES9023. The plan is to create -5v then use 28/72Ohm R or a 100-ohm POT pre-adjusted close... I do not know how much current the DAC would use in TOTAL, the negative rail would consume about 1/2? ignoring any digital stuff. So many regulators are used in DAC designs [including this one], it would be trivial to add one more. I could not find a fixed -3.6V regulator in the first attempt.

grufti 16th March 2013 04:39 AM

The Micrel Inc MIC5205 is available as a 3.6V fixed voltage regulator.

Part Mfg Part # Digikey Part #
MIC5205-3.6 MIC5205-3.6YM5 TR 576-1260-1-ND


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