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Ciúnas ISO-DAC USB DAC Teardown #2

amirm

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#1
I had previously performed a teardown of the Ciúnas ISO-DAC USB DAC. Since that unit was not working and was bought used, there was some doubt as to how original its construction was. As it turned out, another member had a similar unit, sans the option for USB hub that the other unit had. I already performed a review of that ISO DAC. This is a follow up teardown.

Here is a wide shot of the unit after taking apart the two ends and sliding out the top:

Ciúnas ISO-DAC USB DAC Teardown.jpg

Power comes from the right socket supplied by an external switcher. A switching DC to DC converter at the bottom brings that voltage down to what the LiPoFe battery in blue. Hopefully it is set to the correct charge voltage. There are no electrical protections should the output of that Lithium cell shorts out. The same output that goes to the battery also then powers the electronics.

The main DAC chip is the TI PCM5102 as it was in the other unit I tested. The board next to it is mounted upside down and has some IC on it. Both of these boards are hanging in the air with the only mechanism to keep them from shorting being the stiffness of the wiring. Speaking of those, he should be using stranded wires as solid core wiring can fatigue and break.

The longer board below the two is the Amanero USB interface.

Zooming in on the top two boards we see quite a messy assembly:

Ciúnas ISO-DAC USB DAC Board Teardown.jpg

Looks like he bought those boards and hand soldered the ICs on them. There is sign of corrosion everywhere that there is soldering. It tells me maybe it is the corrosive flux that was not cleaned after soldering.

No attempt has been made to keep signals separate, making things nice and neat, and reliable.

Focusing on the battery, we see more examples of this:

Ciúnas ISO-DAC USB DAC Battery nicked Teardown.jpg

Notice that the isolation on the battery has either been torn away or melted. Let's hope and pray that what is exposed is the negative terminal of the battery, not positive. As otherwise, it is millimeters from shorting out to that negative tab.

Same corrosion is apparent here.

The biggest puzzler is the power supply:

Ciúnas ISO-DAC USB DAC Power Supply Charger Teardown.jpg

This is an off-the-shelf LM2596 adjustable switching DC to DC converter. It sells on Amazon for $7 with prime shipping included. That is not the big deal. The big deal is that its output goes to the battery directly and then proceeds to the rest of the electronics. Translating, there is no isolation at all here. Competing products either use relays or FET switches to disconnect the power supply from battery banks. No such thing exists here. As such, call this an "ISO" DAC is just wrong and misleading. No isolation is provided from start (external power supply) to finish (DAC circuits internally).

I don't know if the builder of this product doesn't understand this, or does and still tried to mislead people this way.

Conclusions
This version of ISO DAC is more palatable than the last one because there is less stuffed in it. But otherwise, it is a horrible example of how bad audio electronics can be. There is not one professional engineer that would look at this with anything but disgust. No wonder there are dire warnings in the manual that if you open it, it breaks and voids your warranty. That is wrong. He simply doesn't want you to look a the mess inside this unit.

I had told the owner that I would look to see if I could make it better. But there is just no way to remedy the faults here. Double-stick tape that is used throughout the unit to hold everything from battery to power supply will eventually fail causing these components to come lose to potentially catastrophic end.

The only bit of "good news" is that the cell chemistry used, LifePo4, is quite resilient with respect to abuse. Unlike other chemistry used in EV cars and laptops/tablet/phones, you could short it out, hit it with a hammer and it won't explode due to thermal runaway. It will complain bitterly by outgassing but it is safer technology. They are not used more broadly because their energy density is not as high.

The builder is welcome to come here and explain to us how any of this is acceptable engineering, design and production standards. Until then, my message is simple: please avoid this device. If you have one, I suggest writing to John and asking him if he guarantees the safety of this device in writing. If he does, then maybe you can sell it to others. If it were me, I would take it a recycle place for its battery and write it off as a failed purchase, and not saddle the next owner with it.

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RayDunzl

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#2
Not good.

Next.

(I kinda like solid core wire, though)
 

solderdude

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#4
Amir, You are not seeing this in the proper perspective.

In your pictures the green PCB's obscure the already great Amanero board. What is not seen is that all capacitors on this board have been replaced by super high quality oil-paper capacitors made in mother Russia.
The resistors have been replaced with the right mix of carbon foil and metal foil resistors with 0.001% tolerance.
This is to ensure musicality and bit values having no noise on it.
The chips on the Amanero board have been treated with special materials that enhance the sound quality and isolates the incoming bits from the audio (hence ISO DAC) mounted on sound and vibration absorbing materials instead of metal or plastic which conduct mechanical noise and microphony.

On the left green PCB we see the best sounding and most accurate clock oscillator craftfully bypassed with a super capacitor with the shortest path possible.
This feeds a separate board containing TOTL and carefully selected DAC chip with the best possible harmonic profile. It was hand matched by ear to have synergy with the Amanero board.
Of course it is floating so no vibrations can get to the separate clock generator and DAC board.
Connected with extremely difficult to find silver plated and copper flashed gold wiring.
The solder used may look like it isn't properly soldered but of course it secretly is. It looks that way because the used solder alloy is custom made.
The flux residu you think you are seeing is not that.. it is a special coating that dries up a little funny but provides excellent isolation as to not change the tuning of the board.

Yes, the power supply PCB is cheap... that keeps the price of this DAC affordable. No need to make it more expensive than needed.

You can see the Premium Akku which he bought from Maty, given the bold and colorful lettering.
This ensures a 2nd harmonic dominant profile.
And as one can clearly see on the battery is that one should never dispose of this device. And exactly that is your recommendation in the review so also completely wrong.
Also there is this nice logo on the battery showing the whole device is made of recycled materials so incredibly durable.
Clearly this battery comes from a very well known German OEM manufacturer called 'DANGER'.
Other well known factories for OEM products are the French 'CAUTION' and the Austrian 'WARNING' factories.
Below their logos:
logos.png


Nah .. you got it wrong... this is a marvel of engineering that merely looks poorly. This too is done on purpose so the Chinese won't and can't copy what's under the hood.
 
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#5
I challenge you to write the results of a sighted listening test on that thing without resorting to profanity.
 

BDWoody

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#7
I challenge you to write the results of a sighted listening test on that thing without resorting to profanity.
If this were a date, it would qualify as a double bagger...

I doubt Amir would want to deal with cleaning up the vomit, were he not able to swallow what would inevitably try to come out...
 

WRWSTD

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#10
And again I say, If the battery is connected directly to the components without a regulator or at least a decoupling capacitor, has any thought been given to the AC characteristics of the battery? It is very dynamic with regard to the operating frequency and duty cycle of the load and state of battery charge. Also, if the power supply is recommended to operate the unit, why is the battery there to begin with? Put in a well designed supply to begin with. I am confused....
 

RayDunzl

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#11

Labjr

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#12
Also, if the power supply is recommended to operate the unit, why is the battery there to begin with? Put in a well designed supply to begin with. I am confused....
I think it's there so it will continue to burn, in case of power failure. :p
 
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#15
That is scary looking! A wonder it didnt catch fire!

So he did indeed use a PCM5102 again. That is just such a cheap move. If you are going to design a boutique dac it needs to at least use a high end chip. Alternatively it needs to use a unusual chip that might in theory make some difference, eg multibit or a multibit hybrid like some of the higher end burr brown stuff does.

Even if this were a exceptional implementation of the PCM5102 it would lag behind as that chip is just really bad. It is literally the chip you find in 40 dollar chinese/diy zero effort dacs.

I just cant imagine sitting down to design the BEST DAC EVER and thinking the cheapest bargain bin components were going to be the heart of it. Even without technical knowledge it makes zero sense to think that low end parts would outperform the higher end ones.
 

tomchr

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#19
Looks like he bought those boards and hand soldered the ICs on them. There is sign of corrosion everywhere that there is soldering. It tells me maybe it is the corrosive flux that was not cleaned after soldering.
It's definitely some corrosion related to flux residue. I've never seen it that bad, ever, though. I wonder if solder with water-soluble flux was used. You *have* to clean that up or you end up with a corrosive mess.

Tom
 

mansr

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#20
It's definitely some corrosion related to flux residue. I've never seen it that bad, ever, though. I wonder if solder with water-soluble flux was used. You *have* to clean that up or you end up with a corrosive mess.
I've seen some pretty bad corrosion in an iFi Nano DAC. Everything was played at a multiple of 48 kHz, and the polarity was (bizarrely) inverted. A thorough cleaning brought it back to normal operation. In their dubious defence, the asking price of the Nano is only(?) half that of the Ciunas.
 

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