The ARP Odyssey mkI (model 2800), has the 2 pole 4023 12db/oct filter
It's been described as the most "Arp-like" sounding, because it doesn't try to imitate a Moog..
The mkII has the 4035 24db/oct filter - with a steeper bass roll-off curve, just like the minimoog filter.
The Korg-ARP Odyssey has all 3 filters. Would be nice to compare this with them when the build is done.
The rear virgin PCB
1. ARP Tech schematics for the 4023 filter
2. NLC Blog
3. NLC Build notes