Before I try to answer your question, I feel that it's important that I review some basic laws of physics about how real speakers work in the real world. I'll skip the math and techy stuff and try to present it in easy to understand terms. It all boils down to one basic axiom,and four smaller axioms:
1. The basic axiom: "Everything in designing a speaker is a trade off."
This can also be stated as:
"There no such thing as a free lunch."
or
"You want something; what are you willing to give up to get it?"
These are the four smaller axioms:
1. "Small won't get you big, without some tricks."
2. "To get good bass response, you hafta move the air in the room - a lot of air."
3. "As the frequency goes up, the dispersion narrows."
4. "As the frequency goes down, the bass will roll off dramatically at some point, depending on basic axiom 1."
The problem:
Think of the air in a room as a big bale of loosely packed cotton. You want to move the whole bale of cotton, but all you have is a small stick. (The "stick" is your speaker.) The stick won't move the whole bale; all it will do is poke into the bale and move the cotton near the stick. You need what's called "better coupling". Speakers are like small sticks; they don't do a good job of moving large objects. You need a better way to tie the speaker to the air in the room. You can:
1. Use a bigger stick: You can use a bigger cone, but there are limits to how big you can make it, and drawbacks start to outweigh benefits as the size goes up. if the stick is as big as the room, how do you move the stick? The bigger cone has to be heavier and stiffer, so that it doesn't flex as it moves. Heavier means sluggish. That limits the cone to slower starting notes like pipe organs. Stiffer, yet light cones means more exotic materials (i.e., expensive") like Kevlar, Aluminum, and Graphite Composites.
2. Move the stick more: This was the principle of the acoustic suspension speakers; make the speaker move longer distances to push more air. Unfortunately, it required a lot heavier cone and a long voice coil which dropped the efficiency way down and made the system sluggish as hell.
3. Use a lotta little sticks: The Bose approach, where you use multiple bass drivers to simulate the cone area of a larger driver. The problem is still back to basic physics; even though you equal the area of a large speaker, the cone diameter of each speaker determines one of the low frequency cutoff points, and you pay for the bass boost with phase cancellations and beaming at higher frequencies.
4. Taper the stick from small to large: It's called an acoustic transformer, and that's how horns work. They transform a high energy, large motion, speaker cone to to a lower energy, less motion, signal appearing at the horn mouth that couples better to the air in the room. The problem with low frequency horns is that the mouth of the horn has to be huge and (like every transformer), the throat of the horn (or the transformer's primary) can easily saturate when overdriven.
5. Tie a second stick to the first stick: This is what a Helmholtz resonator does; it can either be done with a tuned hole in the box to move more air in a very small frequency range just below where the speaker starts to roll off (Axiom 5), or by using any tuned mass (like a passive radiator) to move air in that range. The efficiency of this port is tied to a lot of other factors, including cabinet volume.
It's the same principle as blowing across a Coke bottle to produce a note. The air mass in the box and the opening (and duct length) combine to tune the note to a desired frequency, usually just below where the response drops off naturally - around the -3 dB point. A passive radiator serves the same purpose as a tuned port.
6. Use eq to boost the bass and fix problems: That works ok, but only up to a point. You can't fix room nodes electronically, since those are caused by bass buildup over time, and they're different for each room. You can do some slight boost to help a steady dropoff, but you quickly run out of power (or speaker capacity) at very low frequencies.
A brief side trip about Axiom 3: High Frequency Dispersion: This dispersion problem is true of microphones as well as speakers. Even with a perfect omni measurement mic, you have a choice of flat response on-axis, but the high end will drop off as you move off axis, or you can have flat response off-axis, but the high end will increase as you move on axis. With speakers, it's the same thing; as you raise the frequency, the beam narrows and you lose highs as you move further off-axis.
So, what have we learned? Basically, just three things; that (below a certain frequency), a speaker needs help to produce low end, and that bigger is generally better, but not without some compromises. And, we know that above a certain frequency, the high end dispersion begins to narrow as the frequency goes up.
As far as front or back porting, I like front porting myself, but the frequency is probably low enough so that it's non-directional anyway.
