Chinese DAC in a Box: CS8416 / CS4397

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Hi

At the ETF06 I participated at the DAC shootout with my (before) loved Marantz CD63, heavily modified.

You may not believe it: I voted against my own player, at the shootout...

Time for a new start?

Yes! So I had a look, what the winner DAC based of: A Zaholu 2.0 DAC followed by an Aikido balanced stage, transformer coupled (look John Broskies Tubecad blogs , the "Triode centennial" blog).

The Zaholu 2.0 DAC is based on CS8416 and CS4398.

Looking for a Zaholu 2.0 I realized there is a newer version available, the 2.5. A little bit more expensive.

Mr. Wu in Hong Kong is offering various chinese DAC's:

Mr. Wu's sales pages

I found a very cheap (59US$) chinese DAC, based on CS8416 and CS4397, called "DAC in a Box". The datasheet for the CS4397 does not look very different as the CS4398 datasheet.

It's a matchbox sized DAC, just the DAC board. 12VDC, SPDIF optical and RCA in, RCA out.

I immediately ordered on of this boxes, including a small wall-psu. The first tests I made battery operated. I realized, that the DAC is consuming relatively high currents and as soon as the battery voltage is lower than 11V, some clipping occurs (maybe the LT1364 opamp, as the receiver and dac chips are supplied by a low drop AMS1117 regulator with 5VDC).

So, I built a small LM7812 regulated psu and the beast beats my (after ETF06 newly modified) Marantz CD63.

There is no remarkable difference between the California Audio Labs Sigma DAC and this small box!

Of course, I bought this box, to play with my own analoge stage, bypassing the internal opamp.

Maybe, this thread could get as long as the Marantz CD63 thread, as soon as more users start playing with this little box?

Kind regards
Franz
 

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I'm really interested in this little DAC, thanks for posting your thoughts!

Looking at the photo, it seems the opamp is a SOIC package mounted on the PCB. It also looks like there are DIP mounting holes, is this correct?

I've seen another picture showing a SOIC opamp mounted on a kind of DIP converter (I think).

The reason I'm asking is because if I buy one of these, I'd like to replace the opamp with a DIP LM4562.

Best regards,

Andrew.
 
Here the backside of the pcb.

Before replacing the opamp: I think, the opamp is driven by single supply, 5VDC. Therefore coupling caps are sitting in the signal path.

I think, it is better, to bypass this opamp circuit by a complete new, positive and negative rail driven solution.

Or a broskie cathode follower.

Franz
 

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I really regret, not to have bought two pieces of this fantastic DAC's!

One as reference, the other as base for improvement trials.

Actually, I am layouting the breadbord for my testbed (look foto): in the upper left corner the high voltage PSU, tube rectifying (EZ80, resulting in a nice slowstart). CLCRC.

Lower right corner the broskie cathode follower, based on 6111 triodes. The big cans nearby are paper (MP) caps, 4uF.

BTW: I am not in any relation with Mr. Wu, just a customer
:)

Kind regards
Franz
 

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Before replacing the opamp: I think, the opamp is driven by single supply, 5VDC. Therefore coupling caps are sitting in the signal path.

I must correct the above sentence:

The opamp is feeded by a single positive voltage, 11,25 VDC. It comes directly from the power supply over a 1N4407 protection diode, bypassed by a small SMD cap (marked as 336V: is this 33uF 6V?).

That must be the reason, why this DAC begins clipping when the supply voltage is dropping below 11VDC.

Franz
 
Doing some more reverse engineering it is obvious:

I just have to remove the four greenish through hole caps and I will get 4 solder pads for the balanced voltage output from the CS4397 DAC freely accessible and hanging in the air.

So, it will be easy and low risk for the print, to bypass the opamp and add my own audio stage.

Franz
 
Modifications step 1:

Separate regulated voltages for digital (8VDC) and audiopart (12VDC).

Goals:

1. Better resistance to mobile phones, flashlights and so on.
2. Less heat on the AMS1117 regulator, the whole board and caps.
3. Improve the sound...

What I did:

1. Broken powerline nearby AMS1117
2. Removed 1N4007 diode and replaced by a ferrite bead.
3. Attached 12VDC (regulated) at the original points.
4. Added a 22uF tantalum for the 8VDC in.
5. Attached 8VDC (regulated) at the new cap.

At least goal 2 is reached, goal 1 not really (maybe I will use a choke instead of a ferrite bead), goal 3 hopefully :D

Kind regards
Franz
 

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I got mine today and so far I'm pretty happy with it. I haven't tried it with a battery yet, just the supplied plugpack. Compared to my project 85 CS8414/CS4334 DAC it is much quieter, and cymbals sound much more "real". I had no idea how tiny it would be though, that was a surprise! Will listen some more and report back.
 
Modifications, step 2:

I removed the four greenish caps and attached my first version from the Broskie cathode follower:

It works.

But I will rebuild the cathode follower with "real" tubes (E188CC instead of 6111). The problem: One channel was not working, some short between anode and grid. Maybe the tube, maybe the strip board, I used (to small distance between the traces for about 200VDC).

Here, you can see the attachment points for the balanced out from the DAC, after removing the four caps.

Franz
 

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Not very impressed with mine, what difference should I be hearing compared with say a standard internal DAC from a marantz CD67? night and day? I have connected the DAC via coax and optical and with the standard RCA out connected to the amp I can quickly switch between the DAC in box and the marantz via the input select on the amp, cant hear any difference what so ever :whazzat:
 
Have you tried it with a battery? I was going from an a pretty average dac to this one so a definately noticed a difference. I might be wrong, I'm very new to this, but isn't the CD67 pretty good to start with? Remember it's a pretty cheap little unit!
All the best.
 
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