giuliomoro
I've tried connecting headphones to bela's Audio OUT, and I do not hear the same noise that my speakers produce.
Then, I've tried connecting the speakers to Audio OUT as well (not speaker out, as I don't have a DC jack) and the buzzing still occurs.
To be more precise, here is the sound of the speakers, at max volume, when connected to bela (both power and signal, though I did not send ANY signal):
SEPARATE TEST (with headphones):
I've found that sending a signal to Audio OUT actually creates a disturbance in the microphone signals (even if no microphones are even plugged in), see below:
https://i.imgur.com/wmFnyTa.png
In red, the Audio OUT signal sent, and in blue/green, the two microphones (both unplugged).
To clarify, the sent signal WAS played on my headphones, but is way too far from the mics to be picked up even if they were on, or connected, which they aren't.
Edit: This does not happen when I unplug my headphones.
I've also tested with my speakers, and they acted very strange: up to a certain volume, I could hear the signal with no noticeable (might still be present) alteration of the mic signals. When turning the volume of the speakers up, they kinda... crapped themselves, and stopped working with bela. I thought either bela or the speakers died -tested the speakers and they're fine. I think if anything died, it was through bela's usb port.
(Speculation: Should I be using the Speaker OUT signal instead? Is this because I'm using 3.3V instead of Micbias?)
SEPARATE ISSUE (microphone noise):
I need to be able to pick up extremely quiet sounds, but my mic inputs have electrical noise (I assume it's electrical, since it's still present even when the mics are unplugged).
I'd like to get rid of that noise as much as possible, to be able to further my tests with those quieter sounds.
(I've been recommended to use a voltage regulator, and I'm asking here to get other ideas/opinions on the issue).