The Open Baffle
I used Supravox 215rtf bicone and only a cap to 250Hz because I want to limit the high excursion from the cone on higher power responce.
But in the end I choose to go without caps with moderate listening power music without any problems.The Supravox don't need too much power because of high sensitivity (96db) and maximum of 35W will fill the room louder.....depending of the source and music material.If you normaly listen music on high level you can put the 80uf caps in series with Supravox.
The bass extension is amaizing and very good quality.
Best in QUALITY comparing with bass reflex topology.The placement in room make huge differences because open baffle need "air" and space.Behind the ob should have at least 90cm distance (to the wall) and more than this will be ok but less is not recomendet ........the sound become nasty and aglomerated...
For the Alpha's I use an active filter.
I use oak veneer painted with discrete walnut colour and after that ...12 layers of clear laquer and sanding and polished.... again and again...