Mating a sub to vented bookshelf speakers?

[GhettoSQ]

Hi again,
So, my sonotube project is scrapped for now, I hit the limits of WAF. In the interim I inherited some B&W V201s to replace my Boston A60s. I'm fairly surprised by how low they go, and am quite happy with them. On the other hand, I have a nice pair of 8" Seas drivers waiting for a project.

The B&Ws claim to go down to 53Hz, and I'm wondering if adding a sub to a pair of vented bookshelfs is at all wise -- seems like fixing something that ain't very much broke.

I remember figuring out that my Seas drivers are much more suited to sealed (and IB/TL) alignments, but in WinISD, if I mount them Isobarik I can get an F3 of <24Hz with a tuning frequency of 26Hz, all with a ~2.5cu.ft. (72l) box. This would actually fit my room. I could get the MCM plate amp (finally) and cross off at 50Hz or so.

Other than these drivers (CA21RE) being sub-optimal for vented alignments, and the amp having a 12db x-over instead of 24db to mate with the vented mains, am I crazy for wanting to do it this way?

thanks again for listenng to my tired ranting about these white-elephant drivers

[Volenti]

My old DIY pc speakers (bookshelf style, vented 5'') had a response down to ~50hz, I had no issues matching several different subwoofer types with them.

If your B&W's do go down that far then you shouldn't have any issues either.

[GhettoSQ]

I guess I had been thinking it was too low a point instead of too high Also that vented boxes are designed as a start-to-finish system. I realize now that with an acoustic 4th-order rolloff they're pretty ideal. Thanks!