@millercarbon, one thing to be aware of is that there may be more to the difference between a given company’s sealed and ported subs than the sealed or ported enclosure itself. Rythmik Audio offers subs with either a 15" or 18" woofer in both a sealed and ported enclosure, and using the provided foam plugs to block the ports in the ported model does NOT, according to Rythmik design engineer/owner Brian Ding, make them identical (for reasons explained by Ding in the technical pages of the company’s website). Interestingly, his subs using 8" or 12" woofers are offered as sealed designs only, not ported.
Highly technical details on all aspects of sub design are provided on the Rythmik Audio website. Well worth reading, even if you elect to get a sub or four from a different company. Speaking of four subs (a real good idea), as Duke said a swarm can be created from any group of subs, four identical ones perhaps easiest to optimize in a room (for reasons, again, explained by Ding). Another subject covered by Ding is that of mixing sealed and ported subs in a room. Though he recommends not doing it (again explaining why), for anyone insisting on doing so he provides the information necessary to do it correctly. The plate amps on the Rythmik subs include controls to aid in that endeavor, including continuously-variable phase and 3-position damping.
Right. I'm dealing with 4 identical drivers. Two will go in sealed cabs, two in ported. The two ported are larger, because porting calls for more volume.
The point of plugging a port is not to make the ported speaker identical to the sealed one, but merely to alter its output curve. Porting results in a curve that extends flat response a little lower than sealed, but at the cost of output that drops very steeply once it does begin to drop. Sealed begins to roll off quite a bit higher in frequency but at a much lower rate.
Plugging a port won't make the ported speaker identical to the sealed one. It will however make it identical to a sealed enclosure of the same volume. That's the key. There's theory, and then there's practice. Or as a great philosopher once said, "Everybody has a plan until they get punched in the
In practice what happens is plugging a port will cause that speakers output to begin to fall off at a higher frequency. So you got a little too much mid-bass, you plug one port. Still too much plug another.
Also keep in mind this is just one of several ways of getting beautiful flat low bass when using the multiple distributed or Swarm subwoofer system. 1. The location of each of the four subs. 2. Ported or Sealed or plugged port. 3. Phase (one or more can be wired out of phase). 4. Phase Quadrature (Continuously variable, per pair). 5. EQ.
The ground work has been laid. Now comes the work of getting it done.
