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

miro1360

Member
2010-03-20 3:20 pm

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miro1360

Member
2010-03-20 3:20 pm
PCB details
 

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miro1360

Member
2010-03-20 3:20 pm
C37, C38 can be omitted, it is just a simple RC filter on the output (about 330kHz cut-off frequency), my AD1862 is without RC filter
if such a filter is not here after DAC, it will be present at any amplifier input (if not manually removed) :D
the sound is affected by the capacitor type, it is least affected by the type of PP and C0G (SMD) (they have the lowest THD of all capacitor types)
 
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miro1360

Member
2010-03-20 3:20 pm
there are many different tupe output stages, that's why I left the basic opamp with the possibility of Iout for any tube stage ... likewise, power supplies are not on the PCB because everyone prefers something different ... it is only a purely basic solution of the DAC module with endless expansion possibilities
 
there are many different tupe output stages, that's why I left the basic opamp with the possibility of Iout for any tube stage ... likewise, power supplies are not on the PCB because everyone prefers something different ... it is only a purely basic solution of the DAC module with endless expansion possibilities
Fair enough! And thanks for the great work [emoji4]
 

diyiggy

Member
2019-01-16 12:22 am
Hi Miro1360, looks like Pavouk works.


I would suggest you look for the opa861 i/v stage of P Rogic in order to adapt it for the AD1862 or for a discrete stage with BC550/560 * sorted out to putt the I/V resistor at the end and choose a cool one : bulk or damped wirewound in case with a styren as decoupling of a good quality as you like NOS. If needed choose a cool oap for the buffer or a discrete two composant stage.

just my two cents. This chip diserve such cares.



* BC560 are now hard to find, but the smd casing is a possibility.
 

miro1360

Member
2010-03-20 3:20 pm
As i wrote above, people can try different I/V designs. I/V is another chapter.
My intention was not to modify the sound of the AD1862 in any special way (what can be done by I/V).
Iout is present and therefore everyone can connect any converter. Do you know how many good converters are there? including tubes ... life is short to test them all and find the best one :)
My intention is simplicity, not to limit it to a complex PCBs and then through complex adjustments find the right sound :D

Pavouk website is nice source of DAC designs. He tested many different R-2R DACs, but he did not tried AD1862 ... he could finally :D
The schematic of AD1862 is from datasheet, I/V is a simple opamp standard,
shift register part - I don't know who implemented it first .. it's no magic, it's just a bit shifting ...
Eric Juaneda did a lot of work on the shifter:
High End Audio - Digital decoder for NOS DAC
than DDDAC did a lot:
DDDAC 1794 NOS DAC - Non Oversampling DAC with PCM1794 - no digital filter - modular design DIY DAC for high resolution audio 192/24 192kHz 24bit
there was an universal shifter I2S to PCM, a few years ago, I can't find the link ...
I could use the stop clock method with no additional benefit ... many options where to go ... I found this most user friendly, because only SOIC chips are needed and anyone can solder it.
 

diyiggy

Member
2019-01-16 12:22 am
Sorry i didn't see you chose the internal V outputt of the chip.
Pavouk tried the ad1865 Hardware

opa861
is simple, in fact way simplier as it can be seen like a single transistor !

In fact many the I/V can be the same than the internal voltage stage but with better part and it"s a proven fact it sounds best, in others words the voltage output is worse... or maybe it is the ad1865... you know memory and ears ;)

Iancanada said one or two things as well on register iirc. especially about the best in order to data signals
In fact I tried both with this chip voltage and curent and I can tell you the curent output will give yo more of good sound (take it or not of course is your freedom=) or was it the ad1865 you know memory...did I wrote this already ?



Tip if simple is wanted : dc converter heps a very simple way to power the chipto have the best of the voltage outputt



well one can make as simple without more work.


soic : DIR9001 SPDIF decoder or toslink a la ecdesign or USB...

Me lurk about the headphone buffer possibility :)
 

miro1360

Member
2010-03-20 3:20 pm
opa861 output stage can be build separately.

AD1865 is current output too, but it has the possibility of Vout using internal opamp (it sounds not very good, as you already tested). AD1862 is higher lever, more complex architecture.

AD1862 has not Vout, it is current output.
 

miro1360

Member
2010-03-20 3:20 pm
Yes it is 4 layers. Europe based company? They are overpriced for me and therefore, I have no experience with them. For me, the best option is jlcpcb, very high quality, best price for EU (even though manufactured outside the EU), shipping is fast and I am sure you will get it under 20€. This is not an advertisement because I'm not associated with them in any way - just best experience and quality I found yet, if the brands and names of any parts can be mentioned, then I think it doesn't matter. The calculator on their website gives a price for this 4 layer PCB of around 7€ for 5pcs, shipping is similiar.