nos dac AD1865

Analog Device's best DAC chip in the most user-friendly application.
November 2009




I bought my unit with a decent transformer for USD150 from H-K shop Raindrop_Hui. The shipping, handling and packing was perfect.


http://cgi.ebay.pl/DAC-kit-AD1865N-K-NOS-1-0-NOS_W0QQitemZ220513767871QQihZ012QQcategoryZ3280QQcmdZViewItemQQ_trksidZp4340.m444QQ_trkparmsZalgo%3DCRX%26its%3DC%252BS%26itu%3DSI%252BUA%252BLM%252BLA%26otn%3D4%26ps%3D63

A similar story about the same DAC chip is HERE (ROCKNA)
On a general note: this is one of series of DACS which appeared on Ebay recently. It comes from China and it is marketed from H-K. It shares many features with 1500 similar DACS - like power supply concept, some input topology, etc. For example - the massive power supplies - a dedicated power for EACH chip consumer - is based on transistors not regulators. These guys in radiators are transistors ! Very very very rare approach (hopefully less noisy than integrated three leg regulators).
Similar DAC is my older kit - Bloodac s described HERE

Schematics wise - the DAC part seems to be Andrea Ciuffoli design with one of the best DACs AD1865 (by many considered THE best chip ever made)  and the arguably best receiver chip - Cirrus CS8414.  As much as I love AD1865, I think that TDA1541A is arguably more musical, and ESS sabre or AK439X series are slightly better DACs.
On the other hand - if Audio Note use AD1865 in their top dac, that means they tried them all and they chose AD1865 for a reason.
My frequent encounters with Audio Note DAC4 confirm, that this DAC is the worlds best commercial DAC and if I could disconnect my own guilt concerning the children in Africa etc and if I had that money - I would be listening to DAC4 full stop.

Back to the Chinese board:

The output stage is a transistor discrete HDAM lookalike.
The transformer is very decent toroid, surprisingly good at this price point.




On the above picture: in red frame is the DAC power supply (digital part of the DAC) which we need - +5V and +5V - one for DAC chip, one for receiver chip.
Left crossed area is power supplies to the transistor "fake HDAM" output stage. We may use it - actually this stage sounds quite okay! The lampizator version can do without three crossed areas.  (ooops - not true)
Upper right crossed area is the 8 transistor per channel output stage. I like it MORE than any op-amp stage I heard, in fact - despite sounding dark - I really like the sound of it.
In my opinion, for many people who are not just ready for lampization - this DAC is a hell of a starting point. It is one of the best bargains in the world of DACs.
It is really plug and play, ready to rock for USD150.





These are the parts I decided to remove: from the small area crossed in yellow ink: digital input transformer and digital input buffer chip. I just twisted both with pliers , sans soldering gun.  I also do not like the silver caps they use close to all chips. I tried oscons there and sounded much better. On this DAC project I used the Tantalums (just for the hell of it) and their addition audibly opened up the sound. Go for blackgate if you have any chance of finding non-fakes (good luck).

( A week later!  I tried my own recipe and --- tadadadada - no music at all. I should not have disconnected the power supply section which I crossed on the picture with yellow ink.
Apparently - the DAC chip needs 4 supply inputs, not two. And the output stage supplies also supply so called analog part of the DAC chip. So when I disconnected the 17-0-17 V supply - DAC went mute. It gave me a silent day, just like a woman.
I reinstalled all power supplies and it started singing again).

   Oh just look - this chip is a N-K best selection, just like in DAC5 from Audio-Note !



Above - 6 tantalums installed (47uF/25V)



In the red circle are two resistors which take the signal from DAC to the output stage. If we lift them, we can steal signal to the lampizator directly from I out outputs (current type).







A quick test with Gucci RCA sockets for analog output.




The digital input RCA is installed with a complete bypass of  digital input transformer as well as the input buffer chip. I went directly by silver wire - from RCA hot to CS pin 9 (Rxp) , and from cold RCA to CS8414  pin 10 (Rxn)



The digital bypass. It is so audible - I can tell you - it is a real thick blanket being removed.








The messy SMD solder job is not me - it is the poor woman in China. From me is the melted blue terminal   ;-)









Details of transformer connection: 2 x 9 VAC for making 2 x +5V DC and 2 x 17 VAC for making +5VDC and -5VDC for HDAM stage.





The centre wires of primaries - 2 x 115VAC are connected to make 230 V primary.

Before trying lampizator - I can recommend this DAC.
Without any soldering - out of the box - the sound is very okay.  If you know what I mean.
The minor weakness is top end  quite dark and shy.

After bypassing of digital transformer and input chip - trebles open up dramatically.
After adding 6 decent caps to the DAC section - sound improves further, it becomes listenable in Lampizator's High End terms.
That output stage is a very safe and solid performer. Not nearly as good as a triode can be, but nevertheless - worth recommendation.



LAMPIZATOR test:


I used for I/U conversion a resistor 300 Ohms.
I installed double tube lampizator:
6H2P-EB configured as SRPP, in cathodes 200 Ohms. In grid to ground resistor - pin 7 to 9 - the converter 300 Ohms. No input cap. I bias = 1 mA
U Supply = 190 V DC
The pins 4 and 21 are I outputs, I floated them by lifting two resistors as on my picture circled in red.
The signal sees ONLY THE TUBE  and nothing else.
No filtering in analog domain is necessary.
The circuit is a 100% NOS.

The sound is really excellent - as I expected from this chip. In my opinion, the circuit is exactly the same as my heavily modded Rockna dac. It is therefore - a Ciuffoli DAC scheme.
The improvement over the transistor stage is not big. All aspects of the music were already there, they just slightly improved - namely the trebles open up, the micro-clues and plankton form an enveloping, engulfing cloud around me and fill up the room. The 3-d effects are totally hallucinogenic.
The sound does not have character of its own, it is VERY neutral and clean, just the way we like it.
With the simplest tube output - this DAC is an immediate easy ticket to Nirvana. Very much recommended, especially over similar TDA1543 and TDA1541 DACs. Also over the CS4397 and 98 DACs like Lampucera and similar. At the time of writing this DAC can only be in the same league with the ess-tech Sabre dacs, AKM AK 43xx series and with the Wolfson 8741 and 42.



A week later

Ooops - another DAC from Raindrop Hui (what a name) the so called Bloodac - which uses 4 TDA1541 was very well lampized by me - 5 evenings worth of testing - and finally I arrived at the following: removed the upper dual DAC board and I made it a double TDA dac. Two is enough.
I removed the digital input transformer.
I removed the digital chip with 14 legs - the buffering logic - 74HCxxx and I went directlt with the i2S signals to TDA legs 1, 2, and 3. Two chips in parallel. I floated the old inputs of i2s coming via three DALE brown resistors. That HC74xxx was just wasting my time in that circuit - its role was maybe maybe questionably necessary for 4 times TDA, but not for 2.
I lifted completely the DAC pins 6 and 25 and wired them in parallel to the tubes.
I used massive power supply with 8 secondaries and 4 cores in total.
I upgdraded 28 decoupling caps on the TDA and I also used oscons for all supply decoupling close to pins 28, 26 and 15 of these chips.

I added 12 earth wires connecting all earth sections of that PCB. I had a feeling that there is too much ground PCB too far away and on too thin traces. So I built a real star from 0,7 mm  copper wire.

That DAc - let me tell you - plays like a killer. It beats the SATCH (almost the same scheme except one dac in the SATCH) and it generally has very serious pretensions to be the best DAC that I know of. I am now listening and already preferring it to the AD1865. Very very small difference, but the TDA - being a TDA - has that something that no other DAC has.
If they were women, AD1865 would be the pretty one, but the TDA would be the pretty AND WISE one.