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

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soonmo

Member
Joined 2020
grunf said:
I'm glad to see tubes instead of op.amps, just keep going.
I used a similar scheme in my first DAC some fifteen years ago. Then I had two great mentors who were doctors for tubes in Croatia, unfortunately they are no longer with us today.
The first thing they objected to was the operating point ECC88 / 6N23P, with 1K in the cathode I ended up at 180R and a current over 10mA. This will be especially pronounced in SRPP junction without output buffer because SRPP itself is quite sensitive to the impedance of the next stage, in fact it should be calculated for a certain output impedance.
That's why I added an output buffer, simply cathode follower with ECC88. It was a big improvement. I played a bit with the tubes and in the end I chose the Ei ECC88 between 6N1P, 6N23P, Tesla PCC88 and Ei ECC88 which I still use today in the DAC in the output buffer.
For me, it was a big leap from op. amps and since then I haven't soldered a single op.amp on the signal path.
Finally, I enclose the scheme that I later used instead of SRPP, it is still a much better solution because you can go with a lower IV resistor and the sound itself was much better then SRPP.
Click to expand...
Hi grunf

Thanks for sharing your experience. Let's test the attached circuit.
Also, can the circuit diagram in the link below be directly applied to AD1862? It looks like a circuit that does I/V using a vacuum tube, so I'm interested.

https://www.diyaudio.com/community/threads/tube-i-v-stage.382184/#post-6954411
 
Jcris

Jcris

Member
Joined 2007
Paid Member
intojazz said:
I need to settle down and just listen for a few days … first thing I noticed is the sound stage has improved.
PSU 1, LM 6171 , jlsounds, late 2012 Mac mini using jRiver player
Impressions to come
And thanks to those watching over me:
Miro, asilker and paddy and so many folks who I will never meet except of course online in this forum
Thanks everyone!
Must listen now…
Click to expand...
Hey everyone,
I’m curious if any amount of burn in/ break in is necessary or recommended for Miro’s dac. I’ve only been using this dac for a couple hours and noticed some scratchy noise from both channels. I will have to listen more to provide more details.
 
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sworder84

Member
Joined 2018
Guys, what do you think? - is it original or china ver? I buy today in the shop.
 

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sworder84

Member
Joined 2018
I'm almost finish the PSU-1. The problem is KG 4700uF. They are too big for place on board. I solder only two of them and the others don't fit:cry:
I want to solder Epcos B41851A5478M000 (4700/25) - they are smaller. Can I?
Unfortunately I could't found resistors from BOM but I have the alternative. That's why it wasn't so neat.
What I have left to do? - measure the voltage of PSU (+5 and +12) without DAC and then connect to DAC board and Amanero, right?
Oh, yes - one more thing - I was planning to build PSU 2 originally and solder J1-J13 2r2 resistors (2,2ohm). Can I use them or I need to change to jumpers? I could't found any LT's but everything was for PSU-1 so I buyed:)
What else to look out for?
Sorry for such many questions but it's my first diy Dac))
 

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C

commstech

Member
Joined 2002
sworder84 said:
I'm almost finish the PSU-1. The problem is KG 4700uF. They are too big for place on board. I solder only two of them and the others don't fit:cry:
I want to solder Epcos B41851A5478M000 (4700/25) - they are smaller. Can I?
Unfortunately I could't found resistors from BOM but I have the alternative. That's why it wasn't so neat.
What I have left to do? - measure the voltage of PSU (+5 and +12) without DAC and then connect to DAC board and Amanero, right?
Oh, yes - one more thing - I was planning to build PSU 2 originally and solder J1-J13 2r2 resistors (2,2ohm). Can I use them or I need to change to jumpers? I could't found any LT's but everything was for PSU-1 so I buyed:)
What else to look out for?
Sorry for such many questions but it's my first diy Dac))
Click to expand...
Is fitting the remaining 2 capacitors under the board an option? It will create the need for a taller chassis though.
Yup , power up the PSU to measure the voltages before connecting to any other boards.
I would let the 2.2ohm remain if they have been soldered already. They are not needed if using PSU1 but they do not take away anything significant from the power supply if you leave them on the board. i have them on the board.
 
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diyiggy

diyiggy

Disabled Account
Joined 2019
Just try 47 to 220 uF general purpose cap i.e. not low esr, and desolder the output 0,1 uF cap.

Problem being to find not too good esr to lowisch the impedance output, do not choose audio cap and not too much high voltage...16 V for instance. Here no silmic 2 or kz or even fm or fc...just try normal caps...the good esr caps on the dac pcb near the loads do the job.
 
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S

sworder84

Member
Joined 2018
diyiggy said:
Just try 47 to 220 uF general purpose cap i.e. not low esr, and desolder the output 0,1 uF cap.

Problem being to find not too good esr to lowisch the impedance output, do not choose audio cap and not too much high voltage...16 V for instance. Here no silmic 2 or kz or even fm or fc...just try normal caps...the good esr caps on the dac pcb near the loads do the job.
Click to expand...
Which caps I should change? 0.1uf - that's Wima but they're located near transistors and near the input. There is no output caps. I don't understand this moment. And why is change needed? Can you tell me please?
 
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