Thank you for all your answers !

Iawallac:

My driver is supplying 4.0v / 15A. I can’t get more right now. The LED should handle 4.2V / 27A … I’m not using any wavian collar. We can’t find them anymore, can we ?

ma tumba:

It would be used in a concert hall. Rather dark and with smoke. It would be quite optimal.

Just a quick picture of the first optic. It's on this strange position that I get the narrowest beam (with the 120mm aspheric lens on top)

So what do you think I should do ?

  • find a more powerfull driver ? (That I'll do)
  • find some kind of wavien collar ?
  • work on the first optic ? (maybe a full spheric one ?)