Thought I'd like to share my JBL DIY with you all.
It consists of 2215 woofers, 2202 lower mid-range, LE85 upper mid-range, 077 UHF.
I constructed and built the crossover with attenuators for the 3 upper elements. Crossover frequencies 230Hz, 1200Hz and 7000Hz. 12db.
The 2202 have a small closed box. The 2215 have the rest of the box, which is quite large. 55 x 55cm footprint. 125cm high. The baffle is tilted 5cm back. The bass reflex is tuned as low as i could. I don't have proper measuring equipment to say the frequency response within +-3db. With frequency generator you can hear them playing down to 18Hz before the big silence.
To drive this I use Norwegian Pre and power amplifier from Doxa. I have Pioneer pd-s06 CD-player. Between the pre and power amplifier I have two mono Techincs equalizers.