I am designing my own MP3 player now. While decoding & all digital backend looks straightforward, I am only puzzled with audio output (i.e. DAC->Amplifier part). My goals are 1: sound quality 2: power efficiency. Price is not important.

My previous approach (looking for I2S DAC with integrated D-class amplifier) seems to be bad idea as for some reason there are just no low-power D-class amplifiers.

I see some DAC's have integrated headphones amplifiers (AB-class). I am scared a little, as they probably eat too much energy...

Other ways might be getting bare I2S DAC and building my own analog frontend on high-quality opamps. Power consumption is still a problem here (+all fun of having dual-rail power on battery powered device).

Any ideas? Or will I have to spend 80-100mW just to drive headphones at 40mW and have barely 10 hours of battery time...

  • \$\begingroup\$ If you want high quality, go with class AB. Class D can be made just as high quality as anything else, but it's not easy. It depends on component quality, PCB layout, etc. Playing music continuously into headphones for 10 hours seems like decent battery life to me. \$\endgroup\$ – endolith May 30 '11 at 20:14

How about one of these Class D amplifier parts which are very efficient?

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    \$\begingroup\$ Can someone explain why they downvoted? \$\endgroup\$ – Thomas O May 30 '11 at 19:40
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    \$\begingroup\$ That's not me :-) But If you click on any of these you will see that they have separate output for headphones, based on usual AB amplifiers. And it's like that for all manufacturers, for some reason they just does not expect users to plug headphones into speaker output for some reason, and that leaves me puzzled. Maybe efficiency/quality sucks at low power. \$\endgroup\$ – BarsMonster May 31 '11 at 0:43
  • \$\begingroup\$ @BarsMonster: Yeah, getting really good efficiency is usually only important at high powers. If you're doing 1 kW at low efficiency, you need huge expensive heavy heatsinks, so it makes sense to use a more efficient, but more complex Class D or Class G, and spend a lot of time getting the best sound out of it. For low powers, it's better to just use a Class AB that works well out of the box. \$\endgroup\$ – endolith May 31 '11 at 14:44
  • \$\begingroup\$ In my case it does matter :-) If I can output sound at 80% efficiency, that just means double battery time :-) That's the question if I can use Class D output on these parts to drive weak headphones with high impedance... \$\endgroup\$ – BarsMonster May 31 '11 at 19:49
  • \$\begingroup\$ 404 on the link, no value either left; worth a downvote. \$\endgroup\$ – try-catch-finally Jul 7 '16 at 5:58

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