[Sticky] USB-C Microphone (official topic)

@ashleigh Yeah, whoops, I meant through-hole components. I'll look into trying that, then.

Songbird Michelle is considerably better than Matt's original.

You can't make it on stripboard because loads of the parts aren't available in through hole.

THT is going out which is an utter insult to people who are trying to learn as it creates a ridiculous barrier to entry. I already had a background (and I had a lot to learn) but there are numerous examples of what appear to be simple circuits that absolutely cannot be reproduced on strip.

The board itself could (in theory) be assembled at home but you need a hot air work station and a lot of patience.

I wouldn't and I designed the thing.

@marcdraco Ahhhh...I'd better not try it, then. Thanks for the warning. In what ways is Michelle most significantly better than the original?

Mostly noise (S/N) which is definitively better, particularly at larger gains.

It's also USB-C (running at 12 MBPS) so everything is on the board. It doesn't have a monitor because I never added one (cost overruns and such).

And now my Apple Watch has conked. How am I going to tell the time now?

@imp-inventor @wecan (I think that's the right handle, darn me and my blithering) hopefully should haves some field experience with it.

There's no such thing as noiseless in electronics (that would require physics to break and that's not on anyone's bingo card).

Michelle has a LOT of features that are available but simply aren't fully realised in this design (they're easy enough to add though).

The INA - (the thing that does what the THAT does) is similarly specced to the THAT1512.

There is space (and it's wired) for stereo but only one channel is available from the CMI108B. The I2S signals can be vampire tapped OR vectored off to another device (like a Pi Pico, STM32, ESP32 etc.)

The digitiser is capable of 192K which is twice the speed of the current offering (x 2 channels folks, I haven't forgotten how to count).

I guess the MAJOR change from Matt's (it's pretty much a ground up re-design) is the use of a very low drive voltage for the JFET. I could (conceivably) bump that back to 30v but that's even more cost.

Songbird uses a pair of chained LDOs (low-noise low-voltage regulators) to smooth out the USB voltage at the mic head until you'd be forgiven this was battery powered.

The original suffers not from poor design from on the board, but the utterly awful design of the USB power systems. These cables impress a LOT of noise on both rails and it's rich in harmonics - which makes it a nightmare to get rid of.