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

[TNT]

Woff

//

 

[pistollero]

I m testing opa810. Listened at low volumes and sounded very good.. need to test more with some known musics..

 

[Joseph K]

Huh. I have to admit I had overlooked this new arrival..
Good idea. Will try it!

 

[diyiggy]

Ahaha...
I am guessing but get out the last feedback cap for the second 861in the Vunce's pcb

Told you fellows but discrete the opa 861 as i/v then opa 1656 or ada 4627 as buffers are the great balls of fire...boum. TNT will aprove if he soldered yet .'

 

[Vunce]

My diy time has been very limited lately, but I will try replacing the second opa861 with another type when I get time.
Suggestions for the buffer opamp position? (Must be in SMD package)
Thanks!

Btw, this thread will keep the opamp industry in business, LOL

 

[diyiggy]

Vunce, get out first the few pico feedback cap on the second 861 please :



As well, have you some Allen Bradley 100 to 150R resistors ? 1/8 or 1/4 W ?


The reversed 861 is neutral as buffer and not necessarilly mandated according the following stage. Typically a modern pre/amp doesn't need it but the following resistor after the I/V must be tuned if you use a standalone 861 !


Edit : try CEN/SEN design in smd package : just two transistors ! the J-Fe(s)t is enjoyable but the other non Jfet doesn't need sorting out and is very neutral ! again non mandatory in a normal cable length and a modern amp/pre . But if you use headphoness.... well ! you can also use your smd 861 and a soic 8 single channel 5 V for the buff : new TI's are cool... just guessing !

 

[Vunce]

Ok, got it.
I have two set of I/V boards built, I’ll modify a pair following your suggestions.
That will make it easier to notice the difference in sound by comparing them.

Thanks

 

[diyiggy]

problem with sen/ce is you need another powersupply ! in your case if smd transistors only wanted I would choose something else compatible 5V but in your shoes a good soic/8 5V and wouala !

 

[diyiggy]

I m testing opa810. Listened at low volumes and sounded very good.. need to test more with some known musics..

happy you like it ! ! It makes the I/V job very well but less the buffer job : exactly the opposit of the ada 4627-1 !



But the cool thing is they both are single channels oaps so an eventual layout hack is not mandatory which can be a danger -oscillations?- with some fast dual oaps adapted for single use on the pcb !

 

[Vunce]

I can adjust the output of the onboard regulator by changing feedback resistors.

 

[diyiggy]

can you republish the 861 shematic of you board please ?

 

[Vunce]

Sure!

 

[diyiggy]

Thanks


Supress C10, and raise R8 to 700R. -till to 900R-
Try to hack R10 with a 1/8 W Allen Bradley of the same value. Don't use soldering with silver. You should notice a difference with headphones or good speakers and likes the tonal balance !

 

[happylistening]

for +-12V and +-5V power supplies, it is a headache to me and to the small chassis.
will DC be provided by Switching after Low Noise LDO is not too bad idea?

 

[Paddy Garcia]

I used a pair of Traco isolated dc-dc converters to feed my board from my main 24VDC power supply. This worked well but only after I followed the manufacturer's application notes for filtering. Without the filtering I got a fair amount of audio interference.

 

[Vunce]

.....will DC be provided by Switching after Low Noise LDO is not too bad idea?

Switcher w/filtering—> LDO regulator (TPS7Axx Or LT304X type)—> DAC board

Yes, this type of psu works very well.
For AC/DC switcher the Meanwell IRM series is nice.
For DC/DC switcher Murata MEJ2 and Meanwell DCWN03

Like Paddy mentioned, output filtering is highly recommended.

 

[happylistening]

Thanks for the support
and could I know the power consumption of Miro's board?
I am planning to use LT3045 LDO for +-12V and +-5V, but it provides only 0.5V, is it enough?
Thanks again

 

[Vunce]

Yes.
100mA for 5v and 200mA for 12v is plenty.

You will need 4x TL3045 regs
A pair in series to get +/- 5v
Same for +/-12v

 

[miro1360]

Use the recommended output filtering for the LT30xx regulators to avoid unwanted oscillations.

 

[diyiggy]

the pcbs reg should be the closest as you can with these ic regs as well...