[Galaxy S II General] pspilot:
Hmm ... couldn't find that in the papers, but I'm still not sure, whether I have all of it. Anyway, I don't think it would help, because the output driver is definitely the problem! I know it now for sure, did some more test. But before ...

LOL - very surprising considering your work here! To be honest, my first interest would be 'power'. I'm really no fan of ear-blowing volumes, but certain music needs certain power and the SGS2 fails in that respect. Next I think, if the 'drive' for low-impedance earbuds is missing, nothing else matters. Only if the earphones could be driven properly, I'd be concerned about quality issues you are mentioning. Don't get me wrong, I appreciate your findings, but without a decent analog quality, at least for me the phone is no good player anyway.

Ok, as mentioned I did more measurements and now I'm even more confused :rolleyes:. First I have to say, the extremly low output values I posted a few days ago were really worst-case. First of all, I have another FW/Kernel on the phone meanwhile. Obviously the guy swapped the standard player with one, that also 'lifts' the output like PowerAmp does. At least I can't see a difference anymore between that ROM player and the best, PowerAmp can reproduce. I use the Lite'ning 5.0 ROM but swapped the contained FastMod Kernel with the ninphetamine 2.0.5. Hey, I even don't know exactly why, but I started with that Lite'ning ROM and it was nice. Since 5.0 he uses that FastMod Kernel, which I didn't like regarding the battery life. But I don't follow every bit of the ROM hacking, so I missed notes related to the sound. Still, the stock player was never that loud, I know that.

Anyway, the second problem was my adapter. I had used a standard 3.5mm plug which had a hard time to contact right, when it was not 100% in. Lazy as all developers, I used a really nasty contruction :D ... replaced that now with a proper 4-ring plug, a tiny piece of cable which releases the strain, when I fumble with the load resistors :). So, now my results are really trustyworth - I promise :o. I also produced some audio files with sine waves between 20Hz and 20kHz, white noise, pink noise and all the goodies. I distributed these among the SGS2 of course, but also my 'beloved' iPhone 3GS (soundwise!), a tiny SanDisk Player (old SansaClip) and a very old small Archos MP3. I then checked all their outputs mainly for their driving capability using load resistors, but also different earphones with 16, 32 and (strange) 50 Ohms. I didn't find a really high impedance earphone like the Sennheisers sometimes are, but measured also unloaded and 10k line-in.

I can't post the complete results here, but the bottom line is: all of them are producing output voltages of 2-3V when unloaded, also the SGS2 (2V). Like it or not, the 'stiffest' output has the 3GS, it hardly gives in at 32Ohm, and even with the 16 Ohm earbud (which is my favourite, which I want to use) it reaches 1,6V with a clean sine wave over the full spectrum. But for that clean output you have to reduce the volume by 1-2 notches. At 100% volume the output clips, but still at 2,4V! Now for low leveled records that's very handy to have some reserve. The other players were also all above the 1.2 V mark, only the SansaClip gave in to 900mV @ 16Ohm. The SGS2 looses right awa, even on the 10k line-in!! Not much, but measurable (~0.1V). At 32 Ohm the max. output is ~800 mV and with 16 Ohm its again halfed to 400-420 mV. Guys, thats just too much loss! So all considerations about quality IMHO starts there. BTW, these 2V unloaded where the maximum with PowerAmp. With the 'stardard settings' (which I activated by deactivating PowerAmps 'magic'), all the voltages are halfed!! 1V unloaded, 200mV worst-case (16 Ohm). The original Samsung earbud ist 32 Ohm. So my initial 160mV were probably a combination of the real stock player and my earbud's load.

To be honest, even if I didn't see it in the papers, I have the feeling, that Samsung applied some serial resitors on the headphone output. Maybe protection, maybe some overdone 'EU volume control', whatever. It is NO capacity, since the frequency response is extremly linear. So there's no difference between 20Hz and 20kHz! But the voltage loss looks exactly like a very ordinary resistor devider. I really can't imagine, that Yamaha has such a 'soft' amp on the chip. Unfortunately no resistors are mentioned in the service manual, but ... well, I made my point clear. Oh and my first suspicion about a low supply voltage is also shattered by the manual. According to it, the chip gets full VBat for the headphone amp, which is also proofed by the unloaded output voltage.

Probably I post all of that hoping, that some volunteers are jumping up to tear their phone apart and search for the eval resistors ... seriously, of course want to ignite a spirit to overcome these flaws - no matter how. So many clever guys out there :). Actually the service manual indicates, that the sound chip and some of its peripherials is on the 'right' side to access it, while the phone is still assembled enough, to operate. Let's see when I find the courage for an open heart surgery ... :D.