Psychoacoustics...yumm

I only have a 2-speaker set up at the moment (would really love a quad), and 4-way time-difference panning is a little tricky to test in a patch with only meters for feedback :P

I'll assume you've done the appropriate research about the precedence effect, and if so you should be able to put something together for 4 speakers based around this if it's helpful:

Thank you Tim for the patch. I am looking more for the relation between the delay time and the position of the sound. I don t know if that makes any sense...? :S

it is simpler than you might think: sound travels at 334 meter/second so you can convert from distance to millisecods using a factor of 33.4 and that is it. and in a 4 way panning system (a rectangle) the distance from the source to the 4 corners can be found using simple geometry.

Yeah what he said ^; except I'm no good with the simple geometry :P

A delay of more than approx 33 milliseconds and you'll begin to hear distinct sounds rather than panning. In my patch I've only used a time-difference of 2 milliseconds and it works, so I can't see the need to go much higher than that.