Among the 15" combo offerings, which one would you think has the best qualities to also serve as a small subwoofer for a small PA? I don't mean as in live gig PA, just something you can use for general music on events. I'm thinking I need a solid power amp and I want a cabinet that can take a 15L or 15B if the need arise, and maybe a tweeter than can be turned off. It's OK if thingie is heavy, the objective is to save space. Which also makes me want to avoid dragging around a 19" power amp and a bass preamp.
Not a combo, but a fEARful 12/6, or 15/6 can double as a sub. Your power amp should be crossed to cut everything off above 100hz.
Good way of putting the question. Typically SWR amps have very clean poweramps and don't have HPF's which could help give some Mixed and Mastered music a little more bass feel to the sound. Just use the FX return to feed the combo and bypass the preamp altogether. The Black Beauty comes to mind because it's decent power but there's others...
Very few. Probably just a fEarful 12/6 or 15/6 if you want it to actually function as a good subwoofer.
Might be better to get one of those micro heads then. I really don't want to drag a 19" rack around, at least not more than 2 effects. Definitely no rack with a power amp. A micro bass amp in a bag. Sure.
There are a few combo amps out there that have a low end freq. response that would work for low end reinforcement. I wouldn't call them a substitute for a true "sub", but for a small PA, they would help. Many moons ago we used the power amp in on two Peavey Combo 300's fed from the low side of a crossover @ 250 Hz which was fed by the main out preamp signal of the board. It did wonders for the kick drum & toms mic'd in the PA. I'm not saying a Combo 300 is the answer to your question, but I'm saying you're not the first to think of this. A powered sub is essentially a "low frequency optimized" combo amp without a preamp. If you send a low freq signal to the amp section of a combo amp, you have a similar device, although unlikely to be anywhere near as efficient. Good luck.