AD1865 Board ?

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M

marce

Member
Joined 2007
museguy said:
Hi All,
Does anyone know of a AD1865 board ? The only boards I can find are the:

DIYINK AD1865 R2R Isolated NOS Audio DAC with FIFO reclock

Audio DAC with AD1865 which seems to no longer make the PCB

Anyone have feedback on the DIYINHK Board or suggestions for another ? Thank you !
Click to expand...

The second link has PCBs with NO ground plane, a single sided digital layout will be seriously compromised and for a 24 bit DAC is the worse possible layout, to even get 21 bit resolution takes careful layout, that means at least a ground plane....
 
T

Tam Lin

Member
Joined 2010
museguy said:
Do you have a recommendation about the DIYINK AD1865 R2R Isolated NOS Audio DAC with FIFO reclock vs. the AD1862 R2R Isolated nonoversampling NOS Audio DAC with FIFO reclock ?
Click to expand...

IMO both are crap. You could do a lot better with DIY. Not just in terms of PCB layout and parts quality, but you could do something interesting. For example, use many DAC chips in parallel, like the Aries Cerat or staggered for linear interpolation, like the Trinity, both $$$ DACs. Using a Si570 oscillator would let you optimize for an 18-bit sample frame. AD1865s are readily available from Rochester Electronics.
 
M

museguy

Member
Joined 2013
Dear Tam Lin,
Thank you for the feedback. Can you point me in a direction ? Is their a PCB I could follow ? I am just getting started with DIY DACs.

All the best

Tam Lin said:
IMO both are crap. You could do a lot better with DIY. Not just in terms of PCB layout and parts quality, but you could do something interesting. For example, use many DAC chips in parallel, like the Aries Cerat or staggered for linear interpolation, like the Trinity, both $$$ DACs. Using a Si570 oscillator would let you optimize for an 18-bit sample frame. AD1865s are readily available from Rochester Electronics.
Click to expand...
 
E

Eldam

Banned
Joined 2012
Youcould also stay with the 9023 chip but with a better layout, better poweresupply and better output buffer and staying with I2S output & Raspberry 40 pins header by using uf-l wires and the IanCanada I2S/uf-l plugs adaptator for the RPi ! Same environment but not same sound ;) ! Some tweaking for tastes can be seen in a close dac shematic in the thread " Modyfing the Subbu"

https://www.minidsp.com/products/minidspkits/curryman-i2s-dac

JLSoundlabs sells also a well reviewed little usb DAC with async reclocking (and also a bigger & expensive one) !

As pointed out members here, the layout is more than very important in a DAC and the best dac chips will be wasted with a bad one, and a bad supply as well...

Something more DIY and tweaked !? with an interressant dac chip as well : http://www.diyaudio.com/forums/digi...-check-its-design-mod-not-play-music-not.html ; Abraxalito member has an extended experience about this dac chip and also dac powersupply typologies...
 
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3

3lite

Member
Joined 2016
marce said:
The second link has PCBs with NO ground plane, a single sided digital layout will be seriously compromised and for a 24 bit DAC is the worse possible layout, to even get 21 bit resolution takes careful layout, that means at least a ground plane....
Click to expand...

It's even worse than that. Bad grounding can lead to poor sonic performance even from a great DAC chip.

Anyway, since it's my first post (even though I was here for a while by now) and the topic is about AD1865N, here is my project:

An externally hosted image should be here but it was not working when we last tested it.


4-layer PCB with a whole ground plane on the first inner layer. Second inner layer and the bottom ones are used for power supply planes.

It's a hardware linear interpolation DAC (16x). I took the idea from a guy with TDA1541A, but after some time I was informed that Trinity DAC uses the same idea, too. The only difference is that I have a higher upsampling rate due to amount of DACs.

Also, I have a 2-4x sinc interpolation FIR on Spartan-6 and Artix-7 on the PCB which take cares of the inputs (SPDIF and USB). The FIR interpolation is an option and it does only work up to 192 kHz (4x for 44.1 kHz or 48 kHz and 2x for 88.2 kHz and 96 kHz).
 
3

3lite

Member
Joined 2016
The reason for that is quite simple. There are two PCBs exactly like that which will be put on each other along with I/V PCBs put on top of them. I need to save some space. Total of 32x AD1865N were used for a differential output.

There is a little jumper which tells the FPGA to invert PCM data (e.g. -100 to +100) in which case two PCBs can work in a full differential mode.

It's easier for me to (dis)connect I2S / left justified input that way since otherwise the top PCB would be blocking it. There is plenty of debugging going on on the digital part.
 
M

museguy

Member
Joined 2013
3lite,
That is just not fair !

I am trying to figure out how to make a simple little AD1865 DAC and you create a masterpiece of 16x. I am completely humbled. Congratulations on the fine work.


3lite said:
It's even worse than that. Bad grounding can lead to poor sonic performance even from a great DAC chip.

Anyway, since it's my first post (even though I was here for a while by now) and the topic is about AD1865N, here is my project:

An externally hosted image should be here but it was not working when we last tested it.


4-layer PCB with a whole ground plane on the first inner layer. Second inner layer and the bottom ones are used for power supply planes.

It's a hardware linear interpolation DAC (16x). I took the idea from a guy with TDA1541A, but after some time I was informed that Trinity DAC uses the same idea, too. The only difference is that I have a higher upsampling rate due to amount of DACs.

Also, I have a 2-4x sinc interpolation FIR on Spartan-6 and Artix-7 on the PCB which take cares of the inputs (SPDIF and USB). The FIR interpolation is an option and it does only work up to 192 kHz (4x for 44.1 kHz or 48 kHz and 2x for 88.2 kHz and 96 kHz).
Click to expand...
 
M

museguy

Member
Joined 2013
Simple AD1865 ?

Hi All,
Not wanting to start any flame wars, just trying to learn. Can you please give me feedback on why Lampizator solution below is not a good one ? Thank you !

From Rockna scroll to bottom

A year later

A year later I still could not live with the gap between Audionote DAC4 and the modded Rockna.

I bought the new receiver chip - CS8414 and I wired it to the AD1865 chip directly, without ANYTHING AT ALL taken from Rockna board. This way it became a puristic totally kosher totally NOS version of Andrea Ciuffoli DAC.

No Oversamplig DAC

And that's Ciuffoli applicfation in detail:

DAC End - the AD1865N-K with single ended vacuum output stage

I tried it with one change - lampizator instead of his tube stage.
The end result is MUCH better than Rockna. Change of receiver chip from CS8416 to 8414 and removal of XILINX resulted n such major jump in transparency, clarity, easy flow, natural space. Almost Audionote !

Just follow the Ciuffoli schamatics. It will get you as close to nirvana as you can get for 100 Euro, all parts included. The only situation when I was closer to Nirvana for 100 Euro was the other day in Amsterdam, but that's another story.

The DAC Ciuffoli DAC can be wired on test pcb with holes in about one eevening from scratch. You need 3 chips and a handful of oscons.

3 weeks later:

I am very happy with my DAC which has now ZERO content from ROCKNA - it is just the AD1865 chip with power supply and my own input chip.
Like a new forest that grows on the ashes of the old forest. It is a new experience - showing that simple is better and that NOS rules.

The similar system - much cheaper and better built - can be had from hong kong in form of DIY assembled kit.
I recommend everybody to buy it immediately: NOS1865 DAC
Click to expand...
 
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