Posted on Monday, 19th March 2012 by Auw Jimmy

As usual, local audio DIY group in Indonesia held a routine group meeting and gathering. This time, the topic is DAC. There were several contenders joined this session.

Below is the setup used on that session. CD Player was CEC. Preamp were solid state (Pumpkin-Shunty Balanced Preamp) and tube (Aikido). Power was Aleph J2 ‘clone’. Speaker was 3-way floorstander with Vifa drivers.

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Tags: AD1865, AKM, Bintaro, Blind Test, DAC, J2, Pumpkin-Shunty, TDA, Yaqin
Posted in DIY Audio, Indonesia | Comments (12)

Posted on Friday, 8th July 2011 by Auw Jimmy

AD1865 was build from some different factory around the world. Some may have from Malaysia, some from Philippines, some maybe from anywhere around the world. I collected some old AD1865N, probably from year 90′s and some N-K series from 2000′s. I think, Analog Device also changed the font size. Newer one got smaller font size.

It’s gonna be interesting to see how good the N-K would be, vs the lower grade N series.

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Tags: AD1865, DAC
Posted in Collectible Stuff | Comments (0)

Posted on Monday, 13th June 2011 by Auw Jimmy

Finally, I finish assembling my AD1865 PCB which converts standard I2S to AD1865 LSBJ format. This idea comes from pavouk, which provides the schematic then later I follow to design the PCB. Credit to him for this project.

So below is the appearance from the top side. The AD1865 main chip, followed by some 74HC converter, some DIY inductors and some ceramic bypass capacitors.

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Tags: AD1865, DAC, shinkoh
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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…

Tags: AD1865, I2S
Posted in DIY Audio | Comments (17)