tilt/spley board

I think you need to try it. I would start with the cabs splayed very wide, more than 60 degrees. Play some music or a series of sine waves and walk in an arc at some distance from the cabs. The quiet spot should be obvious with a wide splay. Reduce the angle a bit at a time, repeating the listening test. You should hear the quiet spot get narrower. Repeat this until the quiet spot has just gone, and this is your angle, provided you are not now experiencing any excessive combing.

I would guess the best sound will be at around 40 degrees between cabs, but I have never listened to any of the horns you are using, this is based on using other 60 degree horns.

At which frequencies do you find the 15" has tight dispersion? I wouldn't expect it to have any significant control below ~700Hz, but I still haven't heard an xtro.

Kieran

Saul wrote: is there a mathematical way of working this out?  our xtros keep snapping back square with bass bins vibrating under them.  we also need the tilt when we have the bins stacked 3 high.

is that the bass from the Xtros or from the bassbins if it´s from the bassbins turn that off
cause thats not what you are working with . and you can also try cutting some wedges of ply when you are at the workshop or buy some plastic wedges , this should make things easier.