Posted on Tuesday, 19th April 2011 by Auw Jimmy

There are not many options to go with NOS DAC. One is TDA 1541, and the other is AD1865. Some says, the TDA is better (at least the S1), meanwhile some other say the AD1865 is better (perhaps because it’s used by Audio Note?).

I’ve listened both (TDA 1541 S1 vs AD1865) and I decide to go with AD1865. It’s a matter of choice actually, there is no absolute winner.

The problem with AD1865 is the data input format, which is not I2S common but 16 or 18 bit LSBJ. So basically we need to find way to convert I2S to AD1865 LSBJ format (I will use the I2S output of QLS QA-550).

I prefer to use I2S instead of SPDIF out of QLS QA-550. If we use SPDIF, then we will need to upgrade the SPDIF transformer again (another cost). I think the I2S is better solution at this moment (but we still have problem converting I2S to AD1865 LSBJ).

After digging around, I have concluded two possible approach. First, we can use SRC chip to convert the signal (theoretically, this is possible). The SRC chip also not expensive and not difficult to design.

Second approach is by shifting the data register with the help of 74HCT shift register. I find a design from pavouk and (theoretically) his approaches is a big YES!

Then I layout the simple dual layer PCB, with the help on digital ground section from my good friend, ATP “Creno”. So this is the PCB.

Basically it’s a dual layer 1 oz PCB. I’ve ever thought to make it thicker 4 oz silver plated, but this probably later.

Each supply rail will have its own L-C-C filter. The L should be hand made toroidal one, then filtered with Os-Con or Black Gate, then finally bypassed with ceramic capacitor. The shift registers will share the L-C filter, but also will have their own bypass capacitor.

The AD1865 output shall be the current out, converted to voltage by one I/V resistor each channel  (I have Shinkoh tantalum on hand). The output shall be connected to Lundahl or Sowter step-up transformer (counting budget…) to make sure the current is stable on any load… or directly feed to high-mu SRPP stage like 12AX7.

The converted voltage output probably only 0.3-0.4V. Definitely a step up transformer or high mu tube stage (or combination between step up transformer + low/medium gain tube stage) shall play an very important role here.

I’m still in the middle of the road considering Amorphous or Mu-Metal one. Damned, why this world can’t be simplify with lesser choice?

The result? Not quite sure…






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Posted in DIY Audio | Comments (17)


17 Responses to “AD1865 I2S Input PCB”


  1. Arie says:

    Pak Jimmy,

    projectnya muali berlanjut ya… :) bikin DAC sendiri…

    Mau nanya lagi ya.. :) kalau seandainya digital player kita cuman mampu mengeluarkan signal 16 bit, apakah dengan penggunaan DAC yang 24 bit, signalnya akan tetap 16 bit atau jadi 24 bit ??

    Salam Hangat,

    Arie

  2. Auw Jimmy says:

    Halo Pak Arie,
    Project sih masih banyak, cuman enggak ada waktunya nih.

    Kalo digital player hanya bisa output 16 bit, maka DAC 24 bit juga hanya jalan di 16 bit.
    Kecuali DAC-nya ada feature SRC untuk naikkan bit dan sample rate.

    Thanks.

  3. Agus says:

    Siang ko,
    Ditunggu hasil proyeknya nih. Ngomong2 PCB nya bikin dimana yah? Keliatannya kualitasnya ok tuh.
    Salam

  4. Auw Jimmy says:

    Halo Bro Agus,
    Ini mah biasa aja, bikin di Spectra Bandung, titip teman. Hanya PCB biasa 1oz. Saya malah pengen bikin 4oz tapi di sini ga ada yang bisa, mesti import. Kalo cuman bikin beberapa biji sih mahal di ongkosnya hehehe.
    Thanks.

  5. Arie says:

    Pak Jimmy,

    bagaimana cara kita mengetahui bahwa suatu DAC punya fasilitas SRC (Sampling Rate Converter ya?)..kebetulan saya punya DAC dengan chip PCM1793 + DIR9001. Apakah DAC tersebut punya kemampuan SRC.

    Trims.

  6. Auw Jimmy says:

    Halo Bro,
    SRC biasanya berupa chip sendiri, bukan include di chip DAC.
    Thanks.

  7. Adam says:

    Jimmy, has the I2s to AD 1865 board worked? I am very interested in this, if they work do you sell this board..

  8. Auw Jimmy says:

    Hi Adam,
    Not tested yet, but according to pavouk, it should work.
    Since, practically speaking, this is not my own invention, I don’t think I can sell it.
    Thanks.

  9. tjeret says:

    Wah INFOnya keren Mbah Jim

    Jadi TERPANCING pengen nyobain ini CHIP juga, kebetulan ada HIBAH dari Bro Robby :)
    Kebetulan Teradak yang saya pakai ada I2Snya

    I2Snya sudah saya coba kasih makan ke Mbajing_DAC dan No Problem.

  10. Auw Jimmy says:

    Halo Mbah Ode,
    Monggo dicoba. Saya baru bikin PCB, entah bunyi atau bledus…
    Thanks.

  11. Anonymous says:

    ko jimmy, sy ada kit dac 1865… gmn cara nambahin input usb ya…agar bisa play music dr PC
    thank u

  12. rizal says:

    ko jimmy, sy ada kit dac 1865… gmn cara nambahin input usb ya…agar bisa play music dr PC
    thank u

  13. Auw Jimmy says:

    Hi,
    Mesti tambah interface tambahan USB to I2S.
    Thanks.

  14. Saurav says:

    Hi,

    Can you recommend from where can i get the PCB.

  15. Auw Jimmy says:

    Hi,
    I build myself for the PCB.
    Thanks.

  16. Jean-Louis says:

    Hi from Paris Jimmy, but I also lived in Indonesia between 70 and 73 as a child ! enjoyed much (;-)

    Have the same problem and would like to give a I2S input to my AD1865 NOS SRPP from RaindropHui on ebay. Works great btw (;-).
    Did you have your board working ? Could you compare SPDIF and I2S input ?
    Would you publish or send me your board design ?

    Kind regards
    Jean-Louis

  17. Auw Jimmy says:

    Hi Jean-Louis,
    I think SPDIF vs I2S is not apple to apple comparison. But technically speaking, I2S should be superior.
    The original schematic is not mine, but from pavouk. You can google and find this guy. There are some goodies on his website that could be useful for AD1865 user.
    Thanks.


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