Guru
Joined: 30/06/2020
Location: GermanyPosts: 521
| Posted: 10:39pm 16 Mar 2023 |
Hello!
This ticking is pretty normal (if we are speaking about the same phenomenon). I've noticed this often on cheap PAM8403, too. Does it really come from the Pico? Are you supply the voltage via USB? Often USB is bleeding some harmonics into the audible range, thats why I ALWAYS use ferrite beads and form a lowpass in the Mhz range to avoid this.
Also some points about audio in general:
If I hear via headphones (no amplifier) on the normal picMite audio the audio is fine, but if I go into a PAM8403 there is A LOT of digital noise audible, including some harmonics of the carrier frequency. This has also something to do with the signal before it hits the (power)amplifier input. I would avoid those cheap chineese modules.
I don't even use Volhout filter design but the "original" one and have no problems with the mentioned lowpass filter in the Mhz range (usb noise) and feeding the signal into the LM4871M (datasheet example) circuit driving an 8 ohm load / speaker. This chip can output 3W and is really loud, even with this tiny speaker you can see:
Greetings
Daniel