DIY AD1862 DAC (With The Schematic)

With the great result from my previous DAC built here I could say that the journey for the best multi bit DAC is over. The sound quality from TDA1541A S1 is remarkable especially on the mid range. What could I asking for more? But one day, my friend asking if I could check the others best R2R DAC.

It is the AD1862.

I replied, is it AD1865 you said? No, it is really the AD1862, not AD1865. It is technically better than AD1865. So I will make another DAC with this AD1862 since I already have this DAC IC a few days later. Lucky me:)

AD1862 is manufacture by Analog Design. Based on the datasheet, this is true R2R DAC, 20 bit monotonic means it is require 2 IC for a stereo DAC. The fun fact about this AD1862 specification is very similar to Burr-brown PCM63.

This AD1862 DAC build can be also applied to PCM63 DAC as well, but please consider both of the DAC IC's pin compatibility and layout are completely different.

Back to this AD1862 DAC build, on my hand I got AD1862N-J DAC IC's dismantled from the vintage CD player. It is Esoteric CD player that made around 90's. When procuring the DAC IC or others components, this is what I prefer most. Because I can assure for the authenticity components.

Since the population of this AD1862 is very limited, I don't think you could get it easily today.

For the schematic, there is actually stated in the AD1862 datasheet. Especially for the digital channel separation for right and left is can be achieve by using DF1700 or SM5813. By implementing the channel separation properly like this, theoretically no delay between left and right channel compares to using a simple glue-logic channel separation.

In this build, I am using SM5813.

For the SPDIF receiver, I am using CS8414 and this is where the puzzle starting. There is no schematic stated in the datasheet to connect between CS8414 to SM5813. Not provided by online search anyway. The solution is by reading both datasheet and make sure the mode selection are correct.

Here is the schematic and it is works.

The first section is this CS8414 SPDIF receiver. It is the common schematic for SPDIF input by using 75 ohm resistor and 10 nF capacitor before going to RXP and RXN pin. The CS8414 is on mode 5. You can see the configuration for M0 and M2 is set to high and M1 and M3 is set to low.

Then the second section is how to connect between CS8414 to SM5813. FSYNC to LRCI, SCK to BCKI, and SDATA to DIN is a common connection for both IC to communicate each others.

Then comes for the Master Clock, because I want to make this connection simple, yet better, I prefer using the on chip clock provided by CS8414. The MCK of CS8414 is using here. It is connected to XT1 pin on SM5813. This clock works on 256 fs by setting the CKSL to low and CKDV to high on SM5813. By this method, both IC's are work flawlessly.

Then the third section is the connection between SM5813 to each AD1862 DAC IC's. It is also common connection: WCKO to LE, BCKO to CLK, DOL to Data on left AD1862 and DOR to Data on right AD1862.

The setting on SM5813 is only at pin 16 and pin 17. It is OW20 to low and OW18 to high. This setup creating data output in 20 bit as required from AD1862. If you want to connect to others monotonic DAC IC with different bit, then using this two pin configuration to create 16 bit, 18 bit, or 20 bit data output as stated in the datasheet.

For the AD1862 layout is using the same as stated on the datasheet. I also using an op-amp for each channel for IV and simple Bessel LPF approximately cutting in 50 kHz for remove all digital noises.

With this schematic, I start to build this DAC using universal board like this. I prefer using this kind method rather designing a PCB. I am not good at that anyway. Besides that, this point to point connection is better. The other important things to deal this method is how to design the layout with good grounding points. This is more important to press the noise to minimal.

The DAC board is placed on 15 cm x 9 cm board. It is consist of digital receiver, digital filter, DAC module and analog section.

The next board is for the power supply regulator. This AD1862 need 4 voltage required. They are +5 and -5 volt for the digital section. This can be share with the CS8414 and SM5813 +5 volt requirement. The others are +12 and -12volt for the analog section. They can be share with the op-amps for the analog section.

The good power supply is playing big role in every DAC built. Because AD1862 require separate dual supply DC for analog and digital section, so I split 4 section regulator using the LM317 and LM337 adjustable voltage regulator.

I am using exotic components here. The Black Gate F capacitor are using at the digital supply only. Using this Black Gate capacitor on the digital power supply will improving sound staging and reduce back ground noise quite significant. The price for those capacitors are not cheap and this is actually not necessary.

The remaining steps is only connecting the cables between the transformer to the power supply board and the DAC board.

For the transformer, my favorite, reliable and good performance transformer is this vintage Bando transformer. The secondary output from this transformer are 3 pairs of different voltage. This give me more flexibility and option to choose for the proper voltage requirements.

Actually I have using this transformer many times, such as on my Meridian DAC project here or with this Nakamichi DAC-101 here.

In this project, I am using used steel casing from the vintage, unused Yamaha DAC. It is non exotics casing like my previous DAC built that using expensive aluminum casing, yet this is simply for cost saving but not for performance reduction. This casing is clean and having internal bracing to separate the noise between transformer and the DAC section. This is perfect for this kind application.

This AD1862 DAC is now finished.

This DAC built is not for beginner. I taking so much time reading to the datasheet and solving the connection between the IC's. When designing the board layout, is not really that hard but it is complicated because various voltage requirement by the IC itself.

By looking to the result, I am really happy now.

This AD1862 DAC build is works flawlessly from the first time I turn it ON and the sound is amazing.

AD1862 DAC have the wide sound-stage presentation, rich in detail without give ear fatigue. The detail is really presenting very well and coherent with all audio frequency. The timing and attack are precise without any loosing detail in any music notes. The mid range is somehow in my opinion very clear and slightly warm, as great as TDA1541 but more laid back, more relaxed. The overall presentation very dynamic without any dryness, slightly warm and intimate to the listener.

I could say this AD1862 DAC is filling the weakness of TDA1541 DAC. But they are both having different sound presentation. They are also both top tier DAC, so the subjective and personal sound preference really playing role about which is the best among them.

For me, I don't mind having both DAC since they are top tier multi bit DAC that start to extinct. The sound is wonderful.

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