Dual-diaphragm LDC Circuit Repair/replacement (Is this the right section to ask?)

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Hey everyone its been a while since I got started back to fixing my mics. Now that a seasonal holiday is coming up in my country I finally have some leeway to get back into it. Installed Russell Technologies SM02 circuit board from aliexpress into the boya body.

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Some observations about this circuit: it requires a metallic body to act as a shield otherwise it just picks up interference everywhere. Also maybe because of the way I mounted the pcb and soldering the wires (I had to sand the pcb down about 2mm to fit the height of the mic body bracing), it occasionally makes a very subtle high-pitched whine or pop from shaking the cable/body. I have some idea of how I want to secure the pcb better inside the body but any other suggestions are welcome.

Probably the biggest/unexpected improvement to the mic is actually padding the base of the capsule holder and body with some packing foam to damp internal reflections/resonance. Before this the mic always had a little bit of ringy quality to its sound.

I've kind of figured out how to do the polar pattern switching, so now I'm attempting to find a way to mount the pad/cut/polar switches from the old pcb to this new circuit, but I have some questions about the best implementation for the hpf switch

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If I understood correctly the more simple/straightforward ways to implement a HPF in a Schoeps style circuit is either a cap right between the capsule & FET gate, or a resistor across the capacitors after the drain; in this context which is a cleaner implementation without compromising the quality of the signal? I'm targeting to HPF somewhere between 70-80hz.

Optional implementation of the pad is a capacitor across the gate and drain of FET. Is it correct?
 
I've refitted the pcb today & tried to transfer the 3 way switch over to the new circuit, I might have accidentally damaged a component on the polarization board in the process, because the +60V side sound really muffled and about half as loud compared to the original.

Oh well, I'll do better next time. I switched the front diaphragm to -60V polarization, swapped the LDC backplate wire to the FET Gate; and now I have a mic that can do omni, cardioid and sort of hypercardioid pattern. Might be able to find use for this as a forward facing only mic.
 

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