Subwoofer: should we even use them at all?

You're not the only person to mention the "expanded space" phenomenon. I'm not sure I've ever really experienced it, but it makes some sense if the sub is providing very low level bass throughout the room and that is perceived as ambient special information.

My post was focused more on your chosen x-over point and my guess is that the effect you describe is probably (I'd think) independent of that choice.

Got it. Thanks, Martykl. I am working on a few custom 'tweaks' at the moment. After these I will look further into the active crossover.

What I don't understand is why don't more mid-level to high-end speakers just design their speakers with a subwoofer built in. This, it seems, should eliminate (or at least greatly reduce) the coherency problem?

My mains in my main rig are rated -3db 55Hz, while my office monitors to 44Hz. In either case, I can listen to a lot of music and be mostly satisfied without a sub for acoustic, vocals, jazz, blues, etc., even some rock. But there are times I do not want to be MOSTLY satisfied. And for those times, and when I wish to crank it, I employ a pair of 12" powered subs in my main rig.

The deep, visceral, gut-wrenching, grunt of those subs can fill in the missing parts, transporting me to musical Nirvana and change my MOSTLY satisfied experience to COMPLETELY satisfied. I'll never live without a sub (and preferrably at least two) regardless of how wonderful my mains are.

Rockadanny,

Totally agree!!!