WolfX700 Measurement of iBasso DC02

[WolfX-700]

On Monday, forum member @IVX asked me: Have you measured iBasso DC02? He couldn't believe that a AK4490-based DAC performed so poorly.

Considering this is a very cheap unit --- I got it for less than $ 40. I told him that I would immediately buy one for confirmation.

I received this unit at noon today.

I downloaded the driver from iBasso's website and measured it under ASIO.

This is the result:

 

[IVX]

I guessed that Amir's measurement contains some digital domain issues(like 44.1 beat 48 or so), and WolfX-700 got much more clean FFTs indeed. Finally, dc02 still looks so-so because my $300 Redmi K20 Pro outperforms it with its 3.5mm jack, however, FFT now looks reasonably clear, without a forest of spread tones.

 

[IVX]

WolfX-700, what about the power sweep @32ohm?

 

[amirm]

I guessed that Amir's measurement contains some digital domain issues(like 44.1 beat 48 or so), and WolfX-700 got much more clean FFTs indeed.

That could every well be dependency on how clean the USB bus is that is feeding it. I know mine has fair bit of noise.

 

[IVX]

right, that's why I trust rather a battery powered android.

 

[WolfX-700]

WolfX-700, what about the power sweep @32ohm?

32R

 

[IVX]

looks like ibasso save money on the big enough filter cap around the DAC to make floor flat

 

[Veri]

That could every well be dependency on how clean the USB bus is that is feeding it. I know mine has fair bit of noise.

right, that's why I trust rather a battery powered android.

Honestly makes more sense to test with noisy USB bus, then you know if the cleaning is worth anything.
Not every dongle will be used with battery powered mobile device.

 

[IVX]

Veri
and not every battery-powered mobile device is clean if anyone. So if you want to be sure that your DAC plays the same at PC or Android or whatever, make some efforts to clean the 5V rail of USB.

 

[August]

Does ALL4ASIO affect testing？There is a large gap with the test results of amirm

 

[Veri]

Does ALL4ASIO affect testing？There is a large gap with the test results of amirm

Generally it's painfully obvious when the fault is the ASIO driver (dithering to 16-bit, <96dB results).

The issue seems to be the different quality of USB bus/ports.

 

[IVX]

Veri
that's why I prepared max-resolution optical in/out SPDIF/USB 24/192 device to use AP digital generator with USB DACs without ASIO BTW, I sent one to Amir already, and I'll send the same to WolfX-700 if he wish.

 

[WolfX-700]

Veri
that's why I prepared max-resolution optical in/out SPDIF/USB 24/192 device to use AP digital generator with USB DACs without ASIO BTW, I sent one to Amir already, and I'll send the same to WolfX-700 if he wish.

I certainly hope to get it

 

[IVX]

WolfX-700
ok, I'll solder it for you after CNY, but please, PCBA only, without the case. I hate mechanic works..

 

[WolfX-700]

WolfX-700
ok, I'll solder it for you after CNY, but please, PCBA only, without the case. I hate mechanic works..

As long as it is a finished PCB, I'm worried if my soldering skills will affect performance.

 

[IVX]

no way, it is trivial CM6631A + flash IC + 2pcs optic+3.5mm jacks combos. No analog circuits inside at all, no chance to make it bad. There is the schematic https://www.diyaudio.com/forums/equipment-and-tools/345479-ap2700-digital-options-life.html

 

[Schackmannen]

@WolfX-700 Could you please measure the residual noise level in uV from 20-20 kHz unweighted? From your dynamic range measurement I got it to be about 7 uV, but it must be higher than that because with my Tin T3 IEMs it's got a noticeable noise floor and I don't think they are that sensitive, although I haven't been able to find any numbers on it.
Edit: You're probably aware but it mutes the output after a few seconds of nothing playing, not sure if the DR test prevents that from happening.

 

[WolfX-700]

@WolfX-700 Could you please measure the residual noise level in uV from 20-20 kHz unweighted? From your dynamic range measurement I got it to be about 7 uV, but it must be higher than that because with my Tin T3 IEMs it's got a noticeable noise floor and I don't think they are that sensitive, although I haven't been able to find any numbers on it.
Edit: You're probably aware but it mutes the output after a few seconds of nothing playing, not sure if the DR test prevents that from happening.

I think the best measure to solve your doubts is this:

I intermittently give DC02 a very low signal level and record the RMS output

Here are the measurement results:

But on the other hand, I think there are other possibilities. So I made this measurement (20HZ-90KHZ noise floor):

I doubt if it is due to your IEM modulating it to audible band after receiving high frequency noise

 

[Schackmannen]

@WolfX-700 Thank you very much! I found some specs for my T3s and at 95 dB/mw and an impedance of 16 ohm, a 7 uV noise floor would produce about 10 dB SPL if I did the calculations correctly but to my ears it sounds a lot louder than that. Maybe it's very sensitive to the USB power it gets and mine is simply noisier because of that, seeing as yours performed quite a bit better than the one Amir tested.

 

[WolfX-700]

@WolfX-700 Thank you very much! I found some specs for my T3s and at 95 dB/mw and an impedance of 16 ohm, a 7 uV noise floor would produce about 10 dB SPL if I did the calculations correctly but to my ears it sounds a lot louder than that. Maybe it's very sensitive to the USB power it gets and mine is simply noisier because of that, seeing as yours performed quite a bit better than the one Amir tested.

I forgot to tell you that the dbspl of the second picture has been calibrated based on the T3 data.

It is indeed 10dbspl under the 20-20K bandwidth (I will not update the picture)