Hi, I haven't a problem with my two layers smd version where all the digital came from miro board and all the rest analog and decoupling I redesigned. You can load the gerbers I gave here in the thread (not the miro's link in his blog spot, but a further post, I don't have a link sorry, but someone asked me here so perhaps he can give it). It has two smd op amps stage. Load the gerbers it works and you can redisign from there.
I made a 4 layers without noise as well (much quieter than a 2 two layers for obvious reasons but it is tricky) but not public domain (for obvious reasons as well). No digital noise either.
I have a brief look at the picture you gave and I see many crosstalks and coupling everywhere and "isolation of AGND DGND a little odd w/o the "moat" to be so effective everywhere and even usefull sometimes.
But whatever a 2 or more layers, you should not hear with your ears "noises". The layout of the shift registers can be tricky too.
I made a 4 layers without noise as well (much quieter than a 2 two layers for obvious reasons but it is tricky) but not public domain (for obvious reasons as well). No digital noise either.
I have a brief look at the picture you gave and I see many crosstalks and coupling everywhere and "isolation of AGND DGND a little odd w/o the "moat" to be so effective everywhere and even usefull sometimes.
But whatever a 2 or more layers, you should not hear with your ears "noises". The layout of the shift registers can be tricky too.
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I tried changing the GND connection in many ways, but nothing improved the problem I asked.
If it was a GND crosstalk problem, at least when I tried some of the connection methods, this "digital noise" should have improved. But it didn't!
Sorry for my poor English.
This "digital noise" is a bit like distortion in the high frequency part. At lower volumes, it makes the high frequencies very sharp and very obvious.
If it was a GND crosstalk problem, at least when I tried some of the connection methods, this "digital noise" should have improved. But it didn't!
Sorry for my poor English.
This "digital noise" is a bit like distortion in the high frequency part. At lower volumes, it makes the high frequencies very sharp and very obvious.
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You can see in somme datasheet, some op amps having big quiescent current, typical to be near from Class A for some.
Frankly, adding such a biasing will more harm than help on the ready made pcbs here and adds stray capacitance (and it is a very fast op amp that needs quietness) and strange feedback in an transimpedance op amp scheme, There are more to hunt with the LM6171 first.
Friends. Sorry, I'm not sure if I made a stupid mistake.
Just now, I improved the "digital noise" problem I mentioned by adjusting the AD1862 "OPTIONAL TRIM ADJUSTMENT"! !
I always thought that this adjuster would not bring such obvious "low volume distortion", but the facts tell me that it does! It can significantly improve the "low volume digital noise" I mentioned, at least it is completely gone now. The sound of NOS AD1862 is very real, I like it!
I am very curious, how do you adjust this potentiometer? Use a distortion meter or an oscilloscope?
Just now, I improved the "digital noise" problem I mentioned by adjusting the AD1862 "OPTIONAL TRIM ADJUSTMENT"! !
I always thought that this adjuster would not bring such obvious "low volume distortion", but the facts tell me that it does! It can significantly improve the "low volume digital noise" I mentioned, at least it is completely gone now. The sound of NOS AD1862 is very real, I like it!
I am very curious, how do you adjust this potentiometer? Use a distortion meter or an oscilloscope?
Yes, even w/o you should have no noise you can check with ears. A carefull read of the thread aka RTFM philosophy is a must...
Well, if you have more, I'd love to buy a set - I can figure out what's needed to convert to 115VAC.
From what i understand high quiescent current is not likely to guarantee a higher bias for the output stage, especially in very low noise opamps.
It migth or not according how it is made, you have to look at the shematic when present. It can be also something like VFA that has partial CFA topology according what I read, but I dunno. My ears are my guide, measurements come only after the design respect the rules, then I refine. 5 iterations of my ad1862 pcb to come there... Diminishing return, but it is our jobby, isn'it.
Btw, that is the input stage we focus more here in transimpedance schemes and noise suceptibility.
Btw, that is the input stage we focus more here in transimpedance schemes and noise suceptibility.
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Ok, maybe I can ship the board without transformers. I’ll send you pm next week.
Hey can someone who has a known authentic AD1862 check something for me. I have 2 pairs of chips for sale, but am not sure of their authenticity. Nopants suggested that the feedback resistor (on pin 10 as per the AD1862 Data sheet ) should measure 3K, which is also mentioned in the datasheet. If I am reading the block diagram correctly, I should get 3K between pins 10 and 11, but I am not getting that (one measures 22K, others just measure open). Can someone confirm what they get if they measure a real AD1862?
Thanks
Thanks
I took a pair to measure ~ 3.2K on both.
Another pair of different production lot ~ 2.99k on both
Is the 4 ICs all out of spec or just two ? Ebay risks mostly when buying China (it's a dice throw), I tried once and recieved two chips, one with a broken lead that couldn't be fixed. Rochester via a little grup buy.
Too bad you haven't tested the sound of this DAC, with some work to setuping it at your tastes, it is a very no brainer to listen to music. And it can go very deep according the setup. THE PSU2 is very evolved high transcient s is a little expensive, but good results can be achieved with 78/79xx to have an idea, cost much less. But PSU2 is very good unit that can be used also in a lot of projects.
As far I know, there is an american guy whom sold some AD1862s that seems reliable. And thanks to @Paddy Garcia , many had authentic ones from Rochester.
WHen I bougth my first AD1862s for @Painkiller dac project in what ? 2015 or 2016 from Rochester to France, It Costed me a fortune because the taxes, DHL, pre paid cusstom fees .... and VAT on the transport ! Back then they sold them w/o MOQ.
Too bad you haven't tested the sound of this DAC, with some work to setuping it at your tastes, it is a very no brainer to listen to music. And it can go very deep according the setup. THE PSU2 is very evolved high transcient s is a little expensive, but good results can be achieved with 78/79xx to have an idea, cost much less. But PSU2 is very good unit that can be used also in a lot of projects.
As far I know, there is an american guy whom sold some AD1862s that seems reliable. And thanks to @Paddy Garcia , many had authentic ones from Rochester.
WHen I bougth my first AD1862s for @Painkiller dac project in what ? 2015 or 2016 from Rochester to France, It Costed me a fortune because the taxes, DHL, pre paid cusstom fees .... and VAT on the transport ! Back then they sold them w/o MOQ.
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