Quality of audio output

[mathieu]

I've been trying to get decent audio quality ("decent" = toy-quality sound effects, not audiophile quality) by connecting the DAC output to a breakout amplifier (BOB-11044) connected to a good 8 ohm / 2 W / 28 mm speaker. The result, unsurprisingly, suffers from lots of noise, especially when powering the pyboard through USB. I then added a simple low-pass RC filter (1000 ohm + 0.67 uF), which reduces the noise somewhat but also significantly decreases the maximum output volume (is that expected?). What are my options to suppress most of the audible noise ?

- I thought about buying the AMP audio skin, but I can't find its specs and I wonder if I could replace the original speaker with my own?

- Alternatively, do breakout reconstructing filters exist?

- Could I get better audio quality using the PWM instead of the DAC? I would be losing the DAC.write_timed(), which appears to be the most painless way to play back a wav file on the pyboard.

Thanks in advance for your suggestions.

- Mathieu

[pythoncoder]

Unless my calculator is broken 1000Ω and 0.67μF corresponds to a cutoff of 238Hz so I'm not surprised that volume is reduced. I think you'll need to pay attention to construction details and earthing to get good results - using a low pass filter with a cutoff of 238Hz will attenuate the signal as much as the noise, and wreck any high frequency response.

I haven't time to offer more than this right now, but the subject has been discussed on this forum and there are doubtless tutorials on the web.

[mathieu]

Oh... That was a pretty obvious mistake on my part (in retrospect). Feel like a fool for wasting everyone's time. For the record, I did read a lot of online tutorials and such, including from this forum, but nothing seemed directly relevant to my perceived problem. I'll go back to soldering and try not to embarrass myself next time.

Thanks for taking the time to help,

- Mathieu

[pythoncoder]

This was the relevant thread viewtopic.php?f=2&t=2488 - I had to rush last night so didn't have time to look it up.