DIY electret instrument mic project

Hello - I aim to make an instrument-mounted electret mic (also to be used for recording in general). Phantom-powered -- a battery option would be nice, but I don't want it to be required.



After doing a bunch of half-educated research, I thought I would go with the Zapnspark circuit at the yahoo micbuilder's group. I'd post it here, but I think it's not OK to do so? (File is DIYgenericIntFET.pdf)



I already bought the internal-JFET Primo EM184 capsule, but it's two-wire. The circuit at micbuilders is for the "source-follower" linkwitz-modded Panasonic WM-61A. If I understand correctly, the EM184 is functionally equivalent to an un-modded WM-61A, except that I can't mod the Primo?



So I'm wondering if I can/should use the Primo capsule anyway (with what ramifications?), if I should get a different capsule, or if I should find a different circuit to match the EM184?



I've seen GS member Richard's recommendation for the Rick Chinn "PZM" circuit, but I'm unclear if config 2 or config 2 would be appropriate, if either, for the Primo capsule... and the Zapnspark circuit is appealingly simpler...



Thanks for any insight!

DIY electret instrument mic project