Phantom adapter for electret modification. Any help?

[melodomail]

I got some of these tiny electret mic adapters and there was one faulty so I tryed to copy the layout schematic of this. As the components are all SMD. Maybe it will be helpful for someone..

The addiction I would like to this schematic is a HPF with a 3point switch (Flat-200hz-400hz) but I don't know how to modify this schematic as my electronics knowledge is limited. Is there anyone that can help me to modify this??

According to SMAART analyzer results, there is a build in HPF around 50-63hz but it is low enough for the application I need to use it.

Thank you.

[dmeek]

This is what I get from the PCB photos.
Changing R4 should change the low cutoff. Decrease the value to raise cutoff frequency.
Can you post a clearer photo of the bare board?



edit Looks like someone has already drawn the schematic and analyzed the circuit. Updated my schematic

https://audioimprov.com/AudioImprov/...c_Circuit.html

edit again I updated the schematic-had a few things mixed-up and added component values from the linked page. Since R4 is a fairly low value already it might be better to change C1 and C2 from 1uF to maybe .033 or .022