with the current set up of open baffle alpha's, I would be trying them at 250-300Hz up to 1500Hz.The Alpha's are just not good above 300Hz. At present I run them at 180Hz and crossover to an 8" OB, I then have three different settings on the DEQX up to 700Hz, 1000Hz and 1500Hz, jury is still out on the best of those. Above the 8" is a tractrix horn with BMS 4592ND mid drivers and then a 1000Hz tractrix from 6000Hz up. The plan may be to run the bass horn I am building up to 300Hz, then the audax in a Le Cleac'h 160Hz horn, 400hz tractrix and 1000Hz tractrix. Much depends on the quality of the bass horn. I may be totally happy with the audax in OB and call it a day. From what I have read some favour the Audax in OB, so looking forward to trying some.