Hello,
I am tracking down these problems since a while and I tried many things to see if it is a hardware, software or settings problem.
I am now sure it is not setting problem, even if some settings can make it more evident.
From the fact that almost always the problem is just on the external speaker (= not when using headphones) I would say hardware.
With you, I need to find out if it is just my device or not.
SO I have some tests for you:
1) go in settings/sound/sound effects, and disable clear audio and dinamc normailzer. Click on "sound enhancements" and disable the EQ and also set to all down all the sliders. On the tab "settings" deselect everything. Now play some songs and try this: move the first equalizer slider, the one for 400hz, between 0 and +10. Please note if the sound present some distorsion, noise, crackling(scratching... Then add the second slider. Then eventually see if adding the Setting "xLoud" and the dinamic normalization you hear the distorsion less or more.
I personally can hear a VERY clear noise (like if the speaker is damaged or if you play a frequency which this speaker cannot play).
2) download this app: https://play.google.com/store/apps/details?id=cc.openframeworks.SphereTones
it is a free app to make music. Installing it I have noticed that the sound is not good. I have tried with headphones and it is perfect. So, I ask you please to do the same. It is also kind of funny, you tap to make a sphere and then tap again to create another sphere which goes out of the first and make a sound everytime which collides with the first sphere.
Through the speaker, the sound is distorted.
3) please try also with this app: https://play.google.com/store/apps/details?id=processing.test.springs
another free app to make musik. With this one the sound is distorted also through the headphone. The reviews are good, so apparently if there is a problem is for some reason just with my phone or just with the Z1.
4) do you notice any difference in sound quality during a phone call, through the external speaker or through the headphones?
5) do you notice a ad quality in audio recordings, like audio notes and any app which can record sound?
So, I somehow hope it is just my phone, so I can at least send it to repair.
If it is any Z1, then I bought the false phone.
I could live with that because I still need a waterproof and after all I can use headphones for all those apps, but the phone calls quality is very bad compared to other phones (also cheaper ones). This is disappointing.
Cheers
