They do that alot. Just cut the "zigzag" on the ESP , tack a shielded wi-fi from an old PC wireless card to it ... works good.
I am halfway through the soldering, taking it a lunch break per day. The whole point of this board was packing maximum smart functionality in a 4-layer 10x10cm area. There are indeed compromises, but I think the PIC and linear preamps have been kinda done to death at this point. Trying new things is fun right?
Definitely agree, that is why it's on its own split off opamp output. Audio fidelity is not a requirement on these channels as the ADC is only for a VU meter and possible spectrum analyzer.
Why would I want this? The I2C only goes to the GPIO expander which has no current loop around the analog path/ground,
The metal shielding is key for this, so my 3d printed case would kinda make that impossible. I wonder how much interference the 2.4GHz wifi would really give though. It is really far removed from audable frequencies, and 2 regulators and ferrite beads away from the opamp supplies. Jeanpaul did advice me to add a low pass filter to the input circuit which I will try if all fails.
Or just take the UF,L connector ESP32 😉
