Troel's site is an entertaining read, lots of technical data and measurements. I've got a lot of construction and other ideas from him, but his designs in general don't appeal to me, ie, I doubt I'd ever build one as designed.
He has a penchant for using expensive drivers and especially expensive xover parts, some of which he sells under his own brand, Jantzen.
I was also going to suggest Tony Gee's site (humblehomemadehifi) but he's archived the DIY stuff and gone commercial too.
“You are not special. You are not a beautiful and unique snowflake.” Chuck Palahniuk