When I ran the PP cap the top end was okay, nothing special. I then swapped the "oil" cap in place of the PP cap. The entire top HF response opened up like no tomorrow.

I remeasured the 2 caps and they were "dead on" with the same 4 ufd readings. The oil caps are pretty much "motor start caps", but they make a big difference. I have been collecting all the oil caps I can get my hands on. 1st off, they are not cheap(compared to PP), second is the scarcity of finding them. I have found them in old tube amps, heavy duty high power regulators(like in engineering workshops), and some old speaker systems. (don't tear apart a classic like the Klipsch Heresey's or Altec's just to get these). I found old Heathkit speaker system that was shot(a peek inside at the crossover and I saw the oil caps), so the seller thought he got one over on me. LOL

Just my overactive imagination gone wild again.

Ron