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I could almost swear that you can even create a class-D amplifier with the ATTiny85, with a clock rate of ~15kHz. Obviously it's not going to be ideal for an a

I could almost swear that you can even create a class-D amplifier with the ATTiny85, with a clock rate of ~15kHz. Obviously it's not going to be ideal for an audiophile, but the quality is not too shabby. A fun project for those curious. Still, stick to off-the-shelf class-D amplifiers, such as the PAM8403. https://www.youtube.com/watch?v=O8of40tFsD8 https://www.youtube.com/watch?v=O8of40tFsD8

Nihilartikel 5y ago
That would be really cool. Never got around to trying it, but I'm really curious about the subjective quality on the 12bit A/D conversion looping back to PWM D/A. LoFi effects pedals could be fun.
- lb1lf 5y ago
  -The 12 bit A/D provides a (theoretical) 72dB of S/N, so if you can do that at a decent sample rate to get sufficient bandwidth, the digitizing should be good. As long as the PWM D/A has a good clock to keep the PWM ratio accurate, I think it should be eminently listenable, given a proper reconstruction filter and a decent power supply. It would be fun to try this.
  - GeorgeTirebiter 5y ago
    Check this out -- really good discussion of bits and SNR: https://www.xiph.org/video/vid2.shtml https://www.xiph.org/video/vid2.shtml jump to the 11:00 mark to find out just how many 'equivalent bits' those old cassette 'mix tapes' of yours had...
squarefoot 5y ago
> I could almost swear that you can even create a class-D amplifier with the ATTiny85, with a clock rate of ~15kHz. Pretty sure you can do that. A Class D amplifier is to a class A/B traditional one what a switching power supply is to a linear one, so I would expect to be able to make a class D amplifier using for example a PWM driven H bridge usually employed to drive electric motors, or a chip used to make switching power supplies. If they can work at high frequencies (say 50KHz or more) then they should work; all it's needed is modulating their input or feedback pins the right way. Probably not HiFi for the sensitive ear, still good enough.

Nihilartikel 5y ago

That would be really cool. Never got around to trying it, but I'm really curious about the subjective quality on the 12bit A/D conversion looping back to PWM D/A. LoFi effects pedals could be fun.

lb1lf 5y ago
-The 12 bit A/D provides a (theoretical) 72dB of S/N, so if you can do that at a decent sample rate to get sufficient bandwidth, the digitizing should be good. As long as the PWM D/A has a good clock to keep the PWM ratio accurate, I think it should be eminently listenable, given a proper reconstruction filter and a decent power supply. It would be fun to try this.
- GeorgeTirebiter 5y ago
  Check this out -- really good discussion of bits and SNR: https://www.xiph.org/video/vid2.shtml https://www.xiph.org/video/vid2.shtml jump to the 11:00 mark to find out just how many 'equivalent bits' those old cassette 'mix tapes' of yours had...

squarefoot 5y ago

> I could almost swear that you can even create a class-D amplifier with the ATTiny85, with a clock rate of ~15kHz. Pretty sure you can do that. A Class D amplifier is to a class A/B traditional one what a switching power supply is to a linear one, so I would expect to be able to make a class D amplifier using for example a PWM driven H bridge usually employed to drive electric motors, or a chip used to make switching power supplies. If they can work at high frequencies (say 50KHz or more) then they should work; all it's needed is modulating their input or feedback pins the right way. Probably not HiFi for the sensitive ear, still good enough.