Ciúnas DAC USB DAC Review

[Thomas savage]

Show us a photo of the inside of your latest version. Or do you not have pride in your handiwork?

Can't be giving away the performance secrets..

 

[Stellabagpuss]

Thank you for this correction. I modified the review title and the text.

How come there is no way for an owner to know what the are buying? For this kind of money, you could not afford some label/printing on the unit to indicate the model? Since you admonish people from opening the unit, it seems that a model designation would be mandatory.

To be honest amirm, you can't be surely suggesting that at the time of purchase, the customer didn't know what model they where purchased at the time, of course this would have helped your review to be more accurate, you could have ask JK to confirm this. But choose not to.
You do raise a good point, having a name somewhere on the unit, would help ID it. l sure JK will take note

 

[Thomas savage]

The best answer to this thread is to send in the latest versions with the manufacturers blessing for full testing and tear down.

If there's pride and confidence in their products I don't see why this would not be embraced.

 

[amirm]

LiFePO4 batteries cannot catch fire even if a nail is driven through them (easy to research as battery chemistry was printed on all batteries in the pics) & device is NOT a fire hazard

You are jumping from battery to device. LiFePO4 like other lithium chemistries has exceptionally low internal impedance. Here is the spec:

Internal impedance is 6 milliohm or 0.006 ohm. The voltage rating of the cell is 3.3 volts. Dividing that by 0006 ohm we get the current it can produce: 3.3/0.006 = 550 amps! Let me repeat, this one cell can produce 550 amps of current into the rest of the device if shorted.

You can see the device is actually rated to produce 120 amps for 10 second pulse.

We are talking currents that put car batteries to shame. It will melt and turn the rest of your circuits into fireballs.

You have no current protection whatsoever in this device. Anything post the battery can short out and with it, turn them into little torches.

When I built my LiFePO4 battery bank for my RV, right at the terminal is a fuse. IT doesn't even have a wire leading to it. This is on top of full current and other safety monitoring using a battery management system (BMS) in the rest of the circuit.

You are literally playing with fire here.

Now the case is closed so that provides some relief but heaven help you if the battery shorts out to the RCA terminals and then the short occurs in the rest of the audio system.

Please have your design reviewed by a proper and professional engineer. You can't possibly put the safety of yourself and customers ahead of a few dollars this way.

Net, net, while LiFePO4 batteries are pretty resilient with respect to abuse, what comes out of them is not.

Here are some videos for you to watch if you don't believe what I have explained:

See how there is enough current to easily vaporize the leads on that battery. And sparks and fire are absolutely there.

And that is a little pouch cell.

 

[amirm]

To be honest amirm, you can't be surely suggesting that at the time of purchase, the customer didn't know what model they where purchased at the time, of course this would have helped your review to be more accurate, you could have ask JK to confirm this. But choose not to.

They would know what they ordered, how would they know if they got old or new units when they receive it?

And at any rate, audio equipment is readily sold as used so it better have marking for that reason. This is especially so since the unit is quite unsafe to open and the manufacturer says don't open it.

 

[Stellabagpuss]

The best answer to this thread is to send in the latest versions with the manufacturers blessing for full testing and tear down.

If there's pride and confidence in their products I don't see how this would not be embraced.

I cannot agree more, with that.
What alot of people forget, all this negativity is bad for the hobby in general. We should be encourage manufactures, so they can strive to improve things, instead of cheap and rude comments.

 

[mkawa]

i've used a number of these cells to create an incredibly unsafe but hilarious spot welder. that is how much current they can put out. too many cells and you literally slag the thing you're trying to spot weld. this is so so unsafe. i know i keep being this drum, but this box is a fire hazard.

 

[amirm]

This particular DAC measured is an old device, probably 5-7 years old (could be older - I would only know this if I knew the original buyer) - an older design called JKDAC not ISO-DAC

I want to ask this in a formal way even though I know the answer:

Would you please send one of your latest models for review and testing?

 

[Ciunas Audio1]

Because of this answer I already provided: https://www.audiosciencereview.com/forum/index.php?threads/ciúnas-dac-usb-dac-review.9788/post-263360

From the manual once more: ""It needs a 5V supply through it's charging socket at all times except when the unit is put into storage."

Draining a Lithium battery to zero can almost destroy them. There is no battery management system (BMS) here to shut the unit down prior to the batteries draining to zero so I don't want to chance it.

I don't remember how I tested the Mojo but that device like many other well designed units, has proper battery management system and is designed to run on batteries.

That quote is not from the user guide for the DAC model being measured - it might be more reasonable to evaluate some of your earlier statements/decisions based on the information/context provided by me?

The DAC will run for many hours using a fully charged battery - I don't imagine the measurements run requires more than 6-8 hours of DAC power-up? Should you somehow destroy the battery, I will replace it at my cost shipping to & from you included

As this DAC is 5-7 years old (with it's original battery?) & other battery powered DACs of mine are in the field for longer than 7 years, none have had any short circuit or fire issues & the few battery failures have been because of operator error usually an ebay purchaser or second-hand buyer who doesn't check the website user guides or seller doesn't provide info or buyer doesn't bother with info given. It would appear that the same lack of information has occurred between the provider of this DAC & Amir with regard to operation of it, with regard to SMPS. Lack of such information has led to unusual & incorrect statements/claims - all of which could have been cleared up by me if I had been contacted

The suggestion to keep it on charge permanently in later user guides, is a precautionary measure to avoid such user error.

There is a good audible reason for not using a battery management system.

As I said some users run solely off battery for 'critical listening' but almost everyone confirms that they hear no audible difference when charger is unplugged so they leave it plugged in.

Obviously measurements will be different when running solely off battery

 

[Ciunas Audio1]

I want to ask this in a formal way even though I know the answer:

Would you please send one of your latest models for review and testing?

Can you deal with my bullet points in my first post, correct your misunderstanding/mistatements & do some relevant measurements to prove your objectivity in doing such measurements before asking me, in such a contentious manner, to supply a DAC for review?

 

[amirm]

That quote is not from the user guide for the DAC model being measured

It absolutely is. I typed it word by word from the paper manual that came with it.

 

[Stellabagpuss]

They would know what they ordered, how would they know if they got old or new units when they receive it/QUOTE)

it's called customer service, something that JK has a great record on. I agree with some ID on it, but l don't for one second think that JK would supply a unit that is old, when you have purchased the latest version.
Or are you suggesting that?

 

[amirm]

The person who supplied the DAC supplied the SMPS of unknown quality - I didn't supply this SMPS (this could easily have been checked with the person who supplied the DAC)

I can only test what people give me. What is the right power supply and what difference would it make in the measurements? Can you point me to the right power supply so I can purchase and test with that?

 

[Ciunas Audio1]

It absolutely is. I typed it word by word from the paper manual that came with it.

Sorry but this is isn't correct - I only provide an online user guide not a paper manual - the other DAC owners that have posted here can confirm this.

Maybe the user printed off some manual & provided it to you, did you ask him?

 

[amirm]

Can you deal with my bullet points in my first post, correct your misunderstanding/mistatements & do some relevant measurements to prove your objectivity in doing such measurements before asking me, in such a contentious manner, to supply a DAC for review?

I have addressed them all now.

1. I changed the title and text of the review.
2. Your assessment that this is not a fire hazard is completely wrong. I have provided full explanation of it.
3. The manual specifically says not to run it on battery. Since draining the battery to zero irreparably damages the cell, and the battery is not replaceable, I don't know how you expect anyone to run this on battery anyway.
4. On it not being an ISO DAC, I went on your website multiple times and the only products I could find there was ISO DACs which looked identical to this unit. I also asked the owner what the designation was and he didn't know.

Anything else I have left out?

 

[Ciunas Audio1]

I can only test what people give me. What is the right power supply and what difference would it make in the measurements? Can you point me to the right power supply so I can purchase and test with that?

The solution is in your hands to measure it when powered from battery alone after charging it with the user provided SMPS.
Are you reluctant to do this after the assurances & insurances I gave you?

 

[Stellabagpuss]

I can only test what people give me. What is the right power supply and what difference would it make in the measurements? Can you point me to the right power supply so I can purchase and test with that?

I think in this instance, falling back on, l didn't know, is poor. lt was requested you speak to JK, you choose not too, and its its only that he has replied you are getting involved. You could have privately emailed him, thats what professional people tend to do in my experience.

 

[Ciunas Audio1]

I have addressed them all now.

1. I changed the title and text of the review. - I edited my post which you may not have seen, it is a DAC model called JKDAC

2. Your assessment that this is not a fire hazard is completely wrong. I have provided full explanation of it. - you are wrong & I have told you why both the case is isolated & the batteries are safe chemistry (which you stated too) not to mention that the many devices in the field for the last 10 years or so demonstrate your error

3. The manual specifically says not to run it on battery. Since draining the battery to zero irreparably damages the cell, and the battery is not replaceable, I don't know how you expect anyone to run this on battery anyway. - you choose to ignore what I told you - that the manual you are working from is not the correct one for the device - you are still claiming it is the correct manual?

4. On it not being an ISO DAC, I went on your website multiple times and the only products I could find there was ISO DACs which looked identical to this unit. I also asked the owner what the designation was and he didn't know. - so the owner didn't buy it directly from me which is what I gleaned from the whole uninformed nature of this 'review'

This is exactly the same situation as the previous DAC you had from an ebay user & I could tell you the whole story about this person

Anything else I have left out?

Just everything but heyho

 

[amirm]

Sorry but this is isn't correct - I only provide an online user guide not a paper manual - the other DAC owners that have posted here can confirm this.

Maybe the user printed off some manual & provided it to you, did you ask him?

This is the printed pages as supplied to me:

Is it your claim that these are NOT the manuals for this product?

And that I should have ignored them and ran the unit on batteries anyway?

 

[amirm]

This particular DAC measured is an old device, probably 5-7 years old (could be older - I would only know this if I knew the original buyer) - an older design called JKDAC not ISO-DAC

So that manual I just showed you is not for this unit where it calls is Ciunas DAC? Where is the manual for that?

What was your excuse again for not properly labeling these DACs?