I will also throw in and say that the OC-3 is pretty good octave pedal. It sound great by itself, plays well with other pedals, and can be used with bass and guitar. The polyphonic setting actually works well, unlike some of the other units at this price point. So, you get a lot of bang for the buck.
I have also used an OC-3 to thicken up keyboard sounds on home recordings. It can make a cheap Casio keyboard sound huge. You are only limited to your imagination.
As far as signal chain, for bass guitar: I agree that it should be the first effect in your chain. If it doesn't track well, you can try putting a compressor in front of octaver. That may help.
I have also used an OC-3 to thicken up keyboard sounds on home recordings. It can make a cheap Casio keyboard sound huge. You are only limited to your imagination.
As far as signal chain, for bass guitar: I agree that it should be the first effect in your chain. If it doesn't track well, you can try putting a compressor in front of octaver. That may help.