Hi Jamie,
what sequencer you using?
If your using Cubase then check these tutorials out they show you how to split and treat diff bands sep on cubase
Parallel FX for a VST instrument(intermediate)
Here are four tutorials covering differences of using fx channels vs groups and easy ways of creating a larger, synth sound with movement in Cubase SX 3. Click names of tutorials for links:
They are designed to be watched in the following order:
1. Parallel distortion for a VSTinstrument using pre fader sends to FX channel
2. Parallel distortion with groups rather than FX channels
3. Setting up for multi band effects processing
4. Multiband effects processing drum and bass bass example
On ableton simply drag a audio rack multiband over the relevant channel and then add effects to each of the audio bands in the effects rack.
In logic you can send the signal through one bus with a multiband plug in on it, then copy that bus' channel strip make another bus and use the link function to make the channels mimic each other behaviours. Meaning when you move the cut off point for one of the multiband effects it will move the setting on the multibands on all the other linked channels.