Sorry, I didn't reply to this reply, rather, my own post. The reply above has pictures of the PCB and also attached is the reference circuit.Possibly / likely..? Posting some photos might help.
I'm not sure, although here's a picture of the capsule.The original 990 had a 16mm(?) electret capsule - have they switched to an externally-polarized one?
I'm afraid that's the only schematic I could find.View attachment 115254
your schmtc is incomplete There is a voltage converter on the board
(I was thinking of replacing C3 and C4 and bridging them with a 10K resistor, although this circuit seems to be a little different)Thanks for all the information from everyone, I'll probably try to modify the circuit a little bit later tonight (EST).
and bridging them with a 10K resistor
I'm going to add a low pass filter to the circuit (I also talked to a friend who's an electrical engineer, although he only confirmed it on the circuit that I have sent above). EDIT: I realize that I should increase the resistance value.Whoopsie...
What? Why?
consider adding a 1-10nF capacitor in parallel with R7
Wouldn't that then leave the signal at R6 as just an unfiltered source follower output? It looks like you would get an unfiltered signal on the hot pin and a filtered signal on the return pin that way.
Yeah, and..?
It would cut the slope of the LPF in half. That may not matter, or may even be preferred, just pointing it out as something to be aware of.
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