[Folsom]

I would only BSC 3db, not 4-6db. That'll leave you with almost 93db sensitivity. And since the filter is parallel and has a resistive element in it, you're not really degrading the efficiency of the driver. (efficiency and sensitivity are different)

There is a good chance 8 watt could still get you to 100db, and 20w would get you to 103db. So unless you're entertaining a party, I don't foresee serious problems.

Usually more power is good, but for SET I don't necessarily think that, I think whatever SET sound best is best, as long as it isn't a total flop in power on the wrong speakers. Tubes sound louder, too. They clip very nicely, so 8w often is a bit more.

[FullRangeMan]

Thanks for the Davis link, this 8'' may be a good sound driver but 1100 euros per driver put CommonSense Alnico drivers on the bargain side.

[FullRangeMan]

Going higher power in SET is much more expensive. And IMO using small drivers is a recipe for harsher sound without going multi-driver (horns?).

There is some hi power SET made in USA, the higher price is due the big transformers they use, however in China there is plenty of big SET amps with a lower price, this Bravo sport even point to point wiring and DHT tubed AC rectification, however the output power is in excess of 18W, over the limit for the 6C33, one should send this amp for a local tech to reduce the Bias to 12W for longer tube life.
https://www.amazon.com/Jas-Audio-Bravo-2-3-6C33-Integrated/dp/B008K46K98

[inrank]

If its for OB, high sensitivity and full-range, then I would recommend the Supravox 165-2000.
AlNiCo magnet, smooth response and does not need a tweeter, I love mine with a Decware Zen.

[StevenZ]

I'd go with the 15" Classic Alnico or Super Alnico from CommonSenseAudio.com for single driver open baffle.  Without doubt.

[datman]

I have had a pair of the Audio Nirvana Classic 15 Alnico's in 5.4 cubic foot ported cabinets since 2016, a record for me. The most satisfying speaker I have owned in 40 years.

[FullRangeMan]

I have not listened this driver, but I would avoid the Nirvanas models that have this huge drop at 100Hz, someone have listened one of these models that have this drop?
https://www.commonsenseaudio.com/an15classicalnicospecs.jpg
Datman: do you could say something about the bass under 100Hz as seems you liked the Classic15Alnico?

[planet10]

The Classic10Ferrite is a bargain at $375

That is one of the ones i have heard. It has resonance issues that make it a non-contender.

dave

[planet10]

If you are going OB, and want bass, unless you will need have a monster baffle, will need to be a WAW with a helper woofer for the FR. And that allows you to choose a better sounding FR — usually a smaller one. Martin Kings passive OB article is a good starting point.

The speaker & the system (and the interconnect) have to be considered as a system. And that tempered by room, placement constraints, listening tastes, and how loud you listen.

A WAW also allows the option of biamping which means you can get away with a smaller amp up top and a larger SS amp on the bottom. This means greater levels than if constrained with a single amp.

The only single driver OB i heard with bass was the Visaton B200, but it needs phase plugs at a minimum to sort out its HF dispersion. Still not a narrowish baffle as is fashionable today.

dave