Ed, IIRC, bass response is not "directly proportionate with cone area and excursion", but a square function. That is, to go an octave lower requires four times as much excursion. Perhaps I'm misunderstanding what you wrote.
SPL is a linear function, so, at the same frequency, 3dB requires twice the excursion.
Neither of these is limited to bass. They're true at all frequencies. Of course, room effects will change everything.
I
think we are saying the same thing. Maybe the "directly" part is misleading. How about; "The greater the cone area, and the further it moves, the more air you can pump"?
The trick with the little drivers is to focus (tune) the back wave into a supporting role
below the normal usable (actually more like "practical"; obviously if it isn’t there to begin with, you can't enhance it) response curve of the driver in an infinite baffle. All those little guys are moving in unison, well hopefully anyway, same power, same signal, and the SPL from the port doesn't know the difference between them and the equivalent area X excursion of a larger woofer.
Great in theory,
not so easy in application.
Truthfully the key is here;
First of all, individuals vary in their ability to detect volume differences. All of us vary in this ability depending on the frequency of the sound.
- but since a decibel is a fixed unit, it ignores the frequency dependent nature of our hearing.
Its not about the specs, it's not about TS parameters, it's about how it
sounds. If anyone wants to get serious about sound parameters, here's a good place to get started;
Introduction to the Theory and Design of Sonar Transducers by Oscar Wilson
a modern book, but a great primer for the WWII era transducer theories. Great fodder for sound "specaholics"
Anyway... For us plebian gear heads, it's the way we perceive what comes out of those boxes. Bose figured it out, but obviously uses whacked EQ to get there, IMO the benefit there is portability. I always thought it some how wasteful, or kind of like cheating to do it that way, but hey, Amar Bose is a lot more successful at selling speakers than I ever was!
But that's Hi-Fi gear, and use live music types are decidedly "Lo-Fi" with our stage gear by comparison. I (obviously) think there is merit to the multi speaker array for bass guitar, I don't know if Phil Jones figured it out or not. The stuff certainly is celebrated in some circles, you can find tons of online "love fests" for his gear.
I hear he's even working on a arena bass system using D120F's.
