Sealed, Ported, or Passive Radiators?

A passive radiator is the same as a port, but it can just be tuned by the mass of the radiator verses a HUGE column of air or a port so small it would chuff. BOTH systems will show the maximum port velocity or passive radiator excursion when the active driver moves the least. This is the theory of the critical damping frequency system. The active driver hands off more and more of the work to the port or passive radiator the lower you go. That's good as it minimizes cone excursions at the very low-end improving disortion numbers. It's bad in that the port / radiator can take control of the active driver as it has a lot of acoustic leverage on the active driver the lower you go. New driver integration and suspension allow much better control than past systems (ever hear a JBL L36?).

Ports are tough to do well, because they have two resonance design frequencies, though. One is high enough to give the classic mid bass "hump" many ported speakers are noted for. Air suspension has one resonance hump to manage but needs LOTS of cone excursion to go deep, or BIG woofer area, or both. CAD has allowed a HUGE improvement in ported speakers such that sealed enclosures are almost a lost art. Amazing what a few decades do to design.

Still, each has pluses and minuses. I don't really have room for HUGE ported subs or do home theater so that I need infinitely loud explosions. How loud is too loud on a movie sound track? If the blast didn't turn your guts into paste, it wasn't realistic enough. Music doesn't need to do that, it's enjoyable. Dying standing beside a bomb isn't.

There is a lot of good info on the web on speaker design and when you read about the complexity of ported speaker design, you think, "no way!" Well, amazingly, there is a way today. But, ported or passive radiator cabinet volume is bigger all things being the same (low-end frequency reach). Physics can't be denied just used to perfection in modern ported or passive radiator speakers.

At 120dB you may not get to support your artist too long, or hear them anyway!

Multiple drivers are simply super hard to integrate as every driver is a slave to what it sounds like and is made from, and the overlap to the drivers above and below is critical to sonic integration. The electronics are probably the easier part.

Playing 120 dB, just about any driver will be seeing near maximum cone excursions, and lots of doppler or intermodulation distortion, too. That is a sound that gets hard to hide, so more driver that are driven less for 120dB, may actually be better, even if they aren't as "like" sounding as the mains on up.

So the answer isn't obvious to me at 120 dB!

No, the new 2.7 use passive radiators very nicely.

Andrew, have you tried stacking subs? Sometimes this "blends" four subs into a room well. Also, some stack subs with a footer under them to get them away from the floor some (two subs have ample extension way low without floor reinforcement).

I LOVE subs in systems, too. I have C4's and use two subs! Why? They are good, but not to 30 Hz flat. Every speaker I really like has either been built with TWO subs, or have them added. Once you hear effortless DEEP bass, it's hard to go back. I use two DD10+ subs for stereo. Movies are OK but the subs won't kill you when a bomb goes off (my wife say I should have gotten bigger subs!). There are 50 ways to leave your lover. Big subs might have been one?