Filters

[Kurt Dwight Bleach]

While doing some research into the archives for a project I'm working
on, I noticed some discussion on the subject of Ladder-style VCF's
versus 4 Pole. (Is there a 2 pole? 3 pole? 1 pole? Other types
entirely?) Can they both be used for LP, HP, BP, notch?

I know it's a bit of a technical distinction, but what exactly
differentiates these? What's the difference in sound and is it only
noticeable when self oscillating?

I've got a Korg MS-20, a Prophet 5, an SH101 and an Arp Odyssey. Does
anybody know which uses which kind of filter? Are all Moog filters
ladder type?

Whew, that's a lot of questions. An answer to one or two would be great.
(And sorry for the cross post, by the way, but I couldn't decide which
group would be more appropriate for this question.)