Support and General Use > Hardware
Xduoo x3
saratoga:
^^^ usually more helpful if you get a 3.5 mm cable and measure the output in RMAA. The it is obvious what is wrong.
speachy:
I suspect what's going here is that rockbox currently enables the de-emphasis filter of the X3's CS4398 DAC.
(see https://statics.cirrus.com/pubs/proDatasheet/CS4398_F2.pdf, section 7.3.2)
Whether or not this is "correct" is a matter of how the source material was mastered, but generally speaking, if it was mastered for CDs or DAT (ie just about everything) then use of this filter is appropriate (and expected!) to bring the frequency response back to neutral.
I'm willing to change this, but first I'm going to need to see some sort of test evidence (eg a total sweep run through RMAA) that shows that this behaviour is wrong..
In the mean time, Rockbox has a built-in equalizer function that you can use to tune the output to your liking.
speachy:
--- Quote from: speachy on October 15, 2020, 01:07:29 PM ---I'm willing to change this, but first I'm going to need to see some sort of test evidence (eg a total sweep run through RMAA) that shows that this behaviour is wrong..
--- End quote ---
To follow up to myself, it seems that "modern" [1] audio CDs rarely use pre-emphasis, so this filter probably shouldn't be enabled by default.
[1] loosely meaning "mastered digitally", ie not from an analog recording. Nearly everything since the late 80s qualifies, with the notable exception of classical music which still tends to be pre-emphasized.
RomanB:
Yes. I can corfim that this issue was the de-emphasis filter. Now it sounds OK (i am not able notice any difrence between original and rockbox). I read taht this re-emphasis filter used to be aplay on very old CD with only 14 bits resolution. I think that it is not necessary have this optional turn it on.. Thank you very much for your quick solution.
RomanB:
I have one more question. How it is with hi-res 24bit files. Are they converted to 16bit before sending to DAC or full path is 24 bit?
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