Generally speaking, for JBLs I tend to pull a broad, shallow dip around 500Hz and a sharp notch between 1kHz to 2.5kHz, depending on the box.
If you are looking for a simple solution though, I suggested loading the JRX 115 preset and adjust the settings from there. Or you can try emailing JBL and tell them what you are working with. They tend to be pretty good about providing information like that.
That will make the boxes move as the manufacture recommends. They are not bi-amped boxes so there won't be any crazy sauce in those settings. After that, you have to tune to the room. More of your work will be doing that then making the box sound good in open air.