[Deba]

You can unpack and place the file uploaded by @komedol to the .rockbox folder in the sd card in the previous post, that should solve the problem. It worked for me. Or you can change the font size to 8.

Thanks, it worked. I didn't modify the font files/ font size.

 

[razvitm]

I have a technical question about rockbox on the xduoo x3...
Did a comparison between various DAPs with RMAA.
Devices that have 16 bit DACs have a noise floor of about -130dB.
Devices that have 24 bit DACs have a noise floor of about -140dB.
The xDuoo X3 scored -107dB SNR and a -140dB noise floor using rockbox playing a 24bit 44.1KHz rmaa test file.
The question is, if rockbox doesn't support hi-res, why is the noise floor -140dB instead of -130dB and why is the SNR -107dB instead of -96dB which is the maximum theoretical limit for 16 bits?
 
You can peak at this video for a visual description of the above
https://youtu.be/KXM9VVtphJg?t=2769
 
I suspect that rockbox actually supports 24 bits 48KHz on this player.

 

[yacobx]

I have a technical question about rockbox on the xduoo x3...
Did a comparison between various DAPs with RMAA.
Devices that have 16 bit DACs have a noise floor of about -130dB.
Devices that have 24 bit DACs have a noise floor of about -140dB.
The xDuoo X3 scored -107dB SNR and a -140dB noise floor using rockbox playing a 24bit 44.1KHz rmaa test file.
The question is, if rockbox doesn't support hi-res, why is the noise floor -140dB instead of -130dB and why is the SNR -107dB instead of -96dB which is the maximum theoretical limit for 16 bits?

You can peak at this video for a visual description of the above
https://youtu.be/KXM9VVtphJg?t=2769

I suspect that rockbox actually supports 24 bits 48KHz on this player.

I've heard that the internals can only handle 21ish bits not even 24bit

 

[razvitm]

I've heard that the internals can only handle 21ish bits not even 24bit

The analog part of the internals can only handle the equivalent noise of 21 bits... 

 

[saratoga]

I have a technical question about rockbox on the xduoo x3...
Did a comparison between various DAPs with RMAA.
Devices that have 16 bit DACs have a noise floor of about -130dB.
Devices that have 24 bit DACs have a noise floor of about -140dB.
The xDuoo X3 scored -107dB SNR and a -140dB noise floor using rockbox playing a 24bit 44.1KHz rmaa test file.
The question is, if rockbox doesn't support hi-res, why is the noise floor -140dB instead of -130dB and why is the SNR -107dB instead of -96dB which is the maximum theoretical limit for 16 bits?

You can peak at this video for a visual description of the above
https://youtu.be/KXM9VVtphJg?t=2769

I suspect that rockbox actually supports 24 bits 48KHz on this player.

No audio player ever made can do -140db. Are you sure you aren't confusing the FFT (units of dB/Hz) for dynamic range (dimensionless, usually given in dB)?

 

[razvitm]

No audio player ever made can do -140db. Are you sure you aren't confusing the FFT (units of dB/Hz) for dynamic range (dimensionless, usually given in dB)?

Do you have any idea what a noise ground floor is and what it looks like on a graph?

 

[stellarelephant]

razvitm, cool video! Can you post images of your measurements too? Also, were these all done with the headphone jacks of the different devices? I'd like to see how the X3 line out stacks up. Especially curious about the FFT @ 1kHz from the X3 line out to see what differences in the harmonic distortion profile exist.

 

[saratoga]

  Do you have any idea what a noise ground floor is and what it looks like on a graph?

 
Yes I do?  What I meant is that the dynamic range due to quantization error is not directly related to the noise floor you see on an FFT.  You can have very low noise/Hz but still be 16 bit.  See for example noise shaping in rockbox.  

 

[razvitm]

   
Yes I do?  What I meant is that the dynamic range due to quantization error is not directly related to the noise floor you see on an FFT.  You can have very low noise/Hz but still be 16 bit.  See for example noise shaping in rockbox.  

The bttom line question is: Using a high quality soundcard and a jack to jack cable, how do you test, or what do you do, to prove that the xduoo x3 with rockbox has 24 bit support or not? Can a home user prove the xduoo works in 24 bit mode in rockbox?

 

[saratoga]

The bttom line question is: Using a high quality soundcard and a jack to jack cable, how do you test, or what do you do, to prove that the xduoo x3 with rockbox has 24 bit support or not? Can a home user prove the xduoo works in 24 bit mode in rockbox?

You can just look at the code. Unless something changed it operates in 16 mode.

If you want to measure it, turn off noise shaping and dither, and then use rmaa. Or just compute the ratio of a peak signal to quantization noise. Should be about 100 dB in 16 bit mode.

 

[razvitm]

You can just look at the code. Unless something changed it operates in 16 mode.

If you want to measure it, turn off noise shaping and dither, and then use rmaa. Or just compute the ratio of a peak signal to quantization noise. Should be about 100 dB in 16 bit mode.

I found the dither on off setting, but how do I disable noise shaping in rockbox on the xduoo x3?

 

[razvitm]

razvitm, cool video! Can you post images of your measurements too? Also, were these all done with the headphone jacks of the different devices? I'd like to see how the X3 line out stacks up. Especially curious about the FFT @ 1kHz from the X3 line out to see what differences in the harmonic distortion profile exist.

I used headphone out on the players with only one output jack and i used line out jack on the x3 and x3 because line-out has less noise than headphone out.

 

[saratoga]

  I found the dither on off setting, but how do I disable noise shaping in rockbox on the xduoo x3?

 
Sorry, they are one setting.  Dither turns on/off dithered noise shaping.  

 

[vadergr]

Hello all,
 
Just two (easy i hope) questions.
 
1) In which sd slot/card the custom fw is installed ?
2) What is the procedure to revert to original fw ?
 
Thanks in advance.

 

[fredhubbard2]

1) works in either
2) have hold/ lock switched on when you switch the unit on. original FW will load.