Hi.. i’m building pico project to play small audio clips via dac.. code works on bench.. but sometimes sound crackle or pico reset when clip longer than 5 sec… tried extra caps and slower sampling rate.. maybe power problem or dac wiring??
PCB question… want to make pcb… how to route dac traces from pico to audio amp.. should i put cap near dac or amp?? ground plane tricky… any tips to avoid noise?
This crackling & resets are often power or ground noise issues, especially when the DAC and amplifier start drawing current during longer playback.
Make sure the Pico’s 3.3 V rail is stable and add both a 0.1uF decoupling capacitor close to the Pico VCC pins and a 10uF capacitor near the audio amplifier. I call capacitors “the anitvirus for noise” 
read this decoulping capacitor guide: Capacitors - SparkFun Learn
For the PCB, keep the DAC signal trace short and away from high-current power lines, and route it directly from the Pico to the amplifier input. It also helps to keep the analog audio path separated from digital switching lines (SPI, PWM, etc.). Place any coupling or filter capacitor close to the amplifier input, and use a solid ground plane so the audio signal has a clean return path. If possible, keep the amp and audio traces in a quiet area of the board to minimize noise pickup. Read these guides on gND planes:
So the main issue is probably the power stability and noise coupling. I’ll add the decoupling caps near the Pico and the amp, and keep the DAC trace short and away from digital lines.
For the ground plane, do you recommend splitting analog and digital grounds OR just keeping one continuous plane with careful routing?
