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Old 13th November 2013, 02:52 PM   #71
GaryB is offline GaryB  United States
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Quote:
Originally Posted by jean-paul View Post
Hi I am a skeptic regarding hardwired "tuned by ear" devices and need part numbers and values for real comparisons. "V2.6 had Black Gate NX" really says nothing, sorry
JP,
We discussed this in the earlier "ES9023 / WM8804 S/PDIF DAC Group Buy" thread. Per our earlier discussions and your recommendations at the time, I built one DAC with Black Gate 100uf 6.3v N for AVcc and 4.7uf 50v BG NX for NEG and a 2nd one with BG 100uf 6.3v N for AVcc and 1uf 50v BG NX for NEG. You can see pictures here ES9023 / WM8804 S/PDIF DAC Group Buy and here Power Supply PCB for ES9023 / WM8804 S/PDIF DAC Group Buy
The DAC with the 4.7uf for NEG sounded better and I left the 4.7uf BG in that one. But changing out the AVcc 100uf BG for the 470uf polymer cap that I mentioned earlier was a good improvement for both DACs.

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The polymer caps have such an incredible low ESR that they might cause a resonance circuit when paralleled with small value ceramic caps. I read all this yesterday evening and think polymer caps are very exciting but should be used with attention. Solid polymer caps can not just be used as a replacement in many many cases ! Manufacturers advise to use larger value bypass ceramic caps and explain the whole matter in white papers.
For those interested in reading more about the low ESR of polymer caps and the challenges in bypassing them, I suggest the following link http://www.chemi-con.co.jp/e/catalog...AP_090716e.pdf. It makes me think that increasing the bypass cap for AVcc from 1uf to 10uf MLCC would be worth a try.

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Originally Posted by jean-paul View Post
Ears are not the best instrument when comparing tweaked DACs. The mind also influences matters. You should back up listening with measuring. Also testing should be done and then changes could be implemented by changing footprints, BOM etc. Better than hardware mods after production.
I'm curious to know what measurements you use to validate design choices and parts changes. The bypass effects mentioned with low ESR polymer caps would be hard to measure with anything short of expensive network analyzers, which are definitely out of the realm of amateurs. I do have access to equipment like that at work, but I don't think it's realistic to use that for a project like this.

Thanks,
---Gary
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Old 13th November 2013, 02:54 PM   #72
bcmbob is offline bcmbob  United States
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BB, That's exactly what I was looking for. I just finished a battle with header pins on another project where I eventually had to solder directly to the board/pads. All the available connection methods have their drawbacks. I have found the the small female side of the pin style easily loosen with a lot of on-offs. A dab of RTV helps. I'll probably use a solid fix or pins at the final build. The block may help some during all the activity in the build test/phase.

Thanks.
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Old 13th November 2013, 03:45 PM   #73
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Originally Posted by bcmbob View Post
BB, That's exactly what I was looking for. I just finished a battle with header pins on another project where I eventually had to solder directly to the board/pads. All the available connection methods have their drawbacks. I have found the the small female side of the pin style easily loosen with a lot of on-offs. A dab of RTV helps. I'll probably use a solid fix or pins at the final build. The block may help some during all the activity in the build test/phase.

Thanks.
Glad to help, whilst I'm waiting for the parts GB to materialise in my mail box! Phil (Korben69) must have some task at hand sorting and packing all those parts.
Terminal blocks certainly help in the test phase and I don't think that they are any worse than KK crimp terminals and headers. It's just a matter of preference. As you say, hard wired solder connections are the best for the long term.
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Old 13th November 2013, 03:59 PM   #74
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Mouser has them, I found the gold plated variant (which i don't use myself) in a few seconds:

26-61-4040 Molex | Mouser

They will have the tinned version too but you will have to scroll around yourself. Never mix gold plated headers with tinned plugs or the other way around. just just both with the same plating material.

BTW hardwired soldered connections are in fact worse then crimped/screwed connections but that is another story.
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Old 13th November 2013, 04:03 PM   #75
bcmbob is offline bcmbob  United States
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OK. I'll bite. What's the rest of the story.

Seriously, would like to hear your information. In the end we want what's best in a permanent install.
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Old 13th November 2013, 04:34 PM   #76
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Originally Posted by jean-paul View Post

Never mix gold plated headers with tinned plugs or the other way around. just just both with the same plating material.

BTW hardwired soldered connections are in fact worse then crimped/screwed connections but that is another story.
I would agree that mixing dissimilar contact metals should be avoided, due to the galvanic and thermocouple effects amongst other things. Designing for the minimum number of interfaces between conductors is also a good thing. "High pressure" crimped connections can achieve an airtight connection avoiding surface corrosion and possible diode effect etc. But, if the header pins are soldered to the pcb tracks you still have a soldered joint, not to mention the friction joint between the crimp terminal and header pin.
As JP says that is another story, if not a whole book......
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Old 13th November 2013, 04:59 PM   #77
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Originally Posted by GaryB View Post
JP,

I'm curious to know what measurements you use to validate design choices and parts changes. The bypass effects mentioned with low ESR polymer caps would be hard to measure with anything short of expensive network analyzers, which are definitely out of the realm of amateurs. I do have access to equipment like that at work, but I don't think it's realistic to use that for a project like this.

Thanks,
---Gary
The recommendations of the manufacturers are all I have for the recent polymer caps as I don't have that specific equipment. It is a hobby and not an occupation for me. I can only use what I have and I ordered 220/10 for decoupling Avcc and will bypass it with 2.2 f 0805 X7R (also 2.2 F 0603 for the Vneg pin). Will try out different configuration again. Some manufacturers even give ratios for values when mixing polymer caps with ceramic bypass caps like 3:1 . The point is that they seem to differ in opinion in those ratios Too bad that the Panasonic 470/10 SEPC series with 2.5 mm pitch (for decoupling Avcc/Vpos) is not available here yet. It would fit on the board exactly.

You are right about past posts, I also sticked with 4.7 F tot 10 F for Vneg. At that time I could not notice differences between 100 F or larger ones for Avcc/Vpos. I found the Vneg pin to be a sensitive one for capacitor quality like film, BG etc.

Choices, choices.....
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Last edited by jean-paul; 13th November 2013 at 05:13 PM.
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Old 13th November 2013, 05:23 PM   #78
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OK. I'll bite. What's the rest of the story.

Seriously, would like to hear your information. In the end we want what's best in a permanent install.
With DIYers there is no permanent install I thought ? I burned my fingers too many times thinking I would close the case and just use the device but then ... a new PSU, a new revision DAC PCB, new caps etc. etc. Using Molex KK for some time I can tell it is way easier to replace complete PCBs or to do service on the boards. They are just good connectors for this task. Of course there are knockoffs that are not as good but original ones are fine.

Thanks BackinBlack for neatly steering away a possible disaster regarding discussion on what are the best connections I hope your explanation is enough for Bob.
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Last edited by jean-paul; 13th November 2013 at 05:29 PM.
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Old 13th November 2013, 05:38 PM   #79
bcmbob is offline bcmbob  United States
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So are you talking about the crimp end of the female pin? I had a stock of straight square PC sockets similar to these and would make separate leads with heat shrink tubing. I considered having four mating surfaces instead of a single tab to be an advantage.

I even soldered after the crimp was done. Is that not advised?

JP. I am not interested in a long detailed discussion about connectors or the infamous "my favorite hook-up wire" dialogue. As I said earlier, most of those things end up sounding like the "How many angels fit on the head of a pin?" discussions. Been there - done that. Only seeking your best call as the designer.
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Last edited by bcmbob; 13th November 2013 at 05:46 PM.
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Old 13th November 2013, 06:00 PM   #80
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Tin-plated screw terminal blocks with wire, or crimped gold plated sockets onto gold pin headers. Choices, choices. Whichever suits you I guess.
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