www.megadrum.info

I've tested the positional sensing feature with my snare but it's not very consistent, probably due to not having the rectifier board. I happen to have an assembled analogue board from Admir's edrum design lying around (schematic here) and was wondering if I could use that instead? I suppose I could just go ahead and try it but if it's a definite 'no' it'd save me the hassle.

No, it won't work. It's rectifies only positive half waves.

Ok, thanks Dmitri. Just another question, if I may - could I use the lm324 at all for this, or is it just not suited?

*Edit: it seems to be pin-to-pin compatible with the lmc6034

No, lm324 won't work. In fact not all lmc6034 chips work properly so I don't use it.
You can use one of these:
MCP6L04T
MCP604
MCP6004T