G7 -- Question about polystyrene (styroflex) capacitors

There are two polystyrene (styroflex) capacitors on the mic PCB.  Do they have to be polystyrene, or can something else be substituted, like polyester or polypropylene?

Also, how critical is the 160V rating on those caps?  Obviously, I can go higher in voltage rating; but can I go lower?

Wrong forum - moving it to GroupDIY » Project Specific Discussions » Microphones

Imo, (and that's why they're specified so  ) these two caps NEED to be polystyrene - their excellent long-term stability regarding humidity is one of the important parameters.

As for the voltage, the 10nF across capsule NEEDS to be 160V at least - but I suppose that the 1n grid-coupling capacitor could be a 80V type. Not much space saved though.

Jakob E.

Oops!  Sorry.  Correction noted.  And thanks for the quick reply.