Sansа Clip Zip - Improve battery life

[404_user_not_found]

Successfully completed the runtime test. Amazing results.

Sansa Clip+ with a connected headphone sony mdr-zx300. Repeat track, flac -q8, stored in SD card, default settings.

16h 45m - with "improve_battery_life.patch" (Patch set 5) without lowering CVDD2.
29h 19m - with "improve_battery_life.patch" (Patch set 5) with applied CVDD2 (113 value).

Not sure about stable number of CVDD2 but for me 113 value in my old and new sansa clip+ plays normally on low demand FLAC without a delay in menu.

[Mihail Zenkov]

Fantastic result!

Can you try rise CVDD1 to 20 (in patch it 19), set CVDD2 to 112 and check battery runtime again?

[saratoga]

I've split out the audio changes:

http://gerrit.rockbox.org/1089

If this looks ok I can commit. 


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Another thought:  if changing the voltages is easy, I wonder if increasing the audio supply voltages at higher volume settings would enable higher volumes without decreasing battery life. 

[Mihail Zenkov]

Another thought:  if changing the voltages is easy, I wonder if increasing the audio supply voltages at higher volume settings would enable higher volumes without decreasing battery life.

I measure many variants for audio voltages but can't get better result for volume/THD/power consumption. IMHO DAC limit output voltage and  we can't influence on this.

[saratoga]

Another thought:  if changing the voltages is easy, I wonder if increasing the audio supply voltages at higher volume settings would enable higher volumes without decreasing battery life.

I measure many variants for audio voltages but can't get better result for volume/THD/power consumption. IMHO DAC limit output voltage and  we can't influence on this.

The 0dB voltage should be referenced to some supply voltage, probably avdd1 or 2, or maybe something else.  But the difference will be small, maybe only 1 or 2 dB volume increase so it might be hard to notice without measuring.  I might try testing this when I get chance. 

[Mihail Zenkov]

Output stage based on op-amps. For change gain we should change negative feedback. If we rise supply voltage we don't have gain change. If we set voltage lower than op-amp have need, we have limit volume with huge distortion.

Another variant - get louder signal from DAC, but IMHO we get all possible from it (+6dB).

[saratoga]

Output stage based on op-amps. For change gain we should change negative feedback. If we rise supply voltage we don't have gain change. If we set voltage lower than op-amp have need, we have limit volume with huge distortion.

Thats true for a class AB amp, but do the class D amps in these devices work like that?  My understanding is that the gain is proportional to the supply voltage (since they're really just switching the supply on and off).

Another variant - get louder signal from DAC, but IMHO we get all possible from it (+6dB).

You can do this by increasing the gain in the mixer stage, but it simply distorts due to the limited rail voltage on the headphone amplifier. 

[Mihail Zenkov]

Thats true for a class AB amp, but do the class D amps in these devices work like that?

Are you sure about D class in this player?
I not familiar with class D but in this case we shouldn't have DAC and LDO. Also I not sure is phantom ground possibly on class D.

You can do this by increasing the gain in the mixer stage, but it simply distorts due to the limited rail voltage on the headphone amplifier.

I test this mode before and it have some problem but not sure about clipping. In any case this not have real sense as mixer worse audio quality.

[404_user_not_found]

Can you try rise CVDD1 to 20 (in patch it 19), set CVDD2 to 112 and check battery runtime again?

Crashed after some hours of runtime test.

[Mihail Zenkov]

404_user_not_found:
Ok. Thanks!

saratoga:
Can you provide new test build for clip+ users with CVDD1=20 and CVDD2=113 ?

[saratoga]

Updated builds:

http://web.mit.edu/mgg6/www/rockbox-clipv2.7z
http://web.mit.edu/mgg6/www/rockbox-clipplus.7z

[saratoga]

Clip v2 seems fairly stable unboosted with that patch, but as soon as the clock increases the buttons stop working and the player shuts down (detects power as being held).  Increasing voltages has no effect so I do not think its related.

[Mihail Zenkov]

saratoga:
Can you check clip v2 without CVDD1 and CVDD2 mod? And without sd card.

[sancher]

Updated builds:

http://web.mit.edu/mgg6/www/rockbox-clipv2.7z
http://web.mit.edu/mgg6/www/rockbox-clipplus.7z

I've tested clipplus version (radio, mp3, FLAC, MPC)
Everything is OK!

[saratoga]

saratoga:
Can you check clip v2 without CVDD1 and CVDD2 mod? And without sd card.

I tested with both set much higher and it made zero difference so I do not think the problem is voltage. Instead the button driver seems to fail whenever the CPU is boosted, I suspect because one of the delays is set wrong at high pclk.

By the way, has anyone tested the fuze v2 ? Its the only target I don't have.