DAC AD1862: Almost THT, I2S input, NOS, R-2R

Hey Fellas,
I have also confirmed Miro’s AD1862 NOS Dac board is a sweet sounding success!! The music sounds very good right out of the box. I don’t even have the MSB adjustment components installed. I will have to try a few of the I/V solutions you all have been talking about to maximize my listening enjoyment. IMO, this board can be the foundation for a full featured killer DAC 😀

Thanks for sharing this project Miro 🙂

Cheers,
Vunce
 

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Vunce, thanks for your confirmation! I'm glad we managed to give life to this "forgotten" DAC. This DAC is definitely the perfect core for a killer DAC 😀 That's for sure.
The long journey remains for "the best" I/V. I'm afraid that a final I/V doesn't exist yet and people always come up with something new, from a tube through a transformer to various solid-states 😀 This modular form has an advantage that something new can be always easily tested at a relatively cheap price 🙂
 
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I agree Miro, listening to the chatting today started to make my head spin. So many different ways to perform I/V conversion!!! Where to start first 😕
I don’t think this project has an end, but as the tweaking progresses, it will continue to get better with time like a fine wine.🙂
 
Thanks for the recommendations Miro and Chi0001 🙂
I’m going to add a few of the mentioned opamps to my Mouser list.

I have Tantalum and low esr polymer caps to experiment with.
Also, R8 & R9 have 1K4 resistors currently installed, I will bump them up to 2k4.
 
Here is a measurement through motherboard line in of -60db tone from untrimmed Ad1862 with opa1612 IV (Iv resistor is low in value, 700 ohm or so) :
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THD jumps around from 1-1.5%... but is that accurate? why are their no visible harmonics above the noise?

I think noise floor of ADC will be effecting the accuracy of THD+N but I dont how much noise will influence the accuracy THD only measurements
 

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It was made in audacity.
which potentiometer do you mean? there are none currently, its just straight from IV.

I am not sure about 20 bit, I have only seen this option in HQ Player a long time ago and I think recall it refusing to start playback with an XMOS I2S interface. you can contain 20 bit data in 24 bit file though, not sure how the AD1862+I2S logic would handle that.

that file is 96kHz to give cleaner sines at higher frequency but I think you are right, 192kHz would be better since the old filter chips ran at 16x oversampling.
 
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