Very new ardour user here. In my previous mixes with another DAW I was quite a fan of time stereophony on instruments like bass guitar. A 0.7ms time delay on one channel gives me a good side positioning without loosing any energy on the other side.
There are various plugins that will let you do this, one thing to keep in mind with this technique is that you won’t get good mono compatability depending on the period of the frequency involved. at .7mS you are going to start having phasing issues at about 750Hz on up if mixed to mono(Assuming I remembered my maths right), not saying that you can’t do it, just something to keep in mind.
A combination of amplitude panning and delay will give a powerful spatial cue, and a slight reduction in level of one channel will greatly reduce the comb filtering (I think that’s what Seablade meant by phasing) effect in a mono mix.
For a bass guitar, consider splitting into frequencies above and below 150Hz, and panning only those above 150Hz. that will keep all the LF energy in the centre, and our ears aren’t directional below 150Hz. https://community.ardour.org/node/5370 hints at a way to do this.