Tight bass sub recommendations

I've accompanied both electric and acoustic basses (with and without a pickup going to an amp), and reproducing an acoustic is a more demanding task that reproducing an electric. Most speakers and subs---and most importantly, rooms!, to one degree or another, add a little "plumpness" to the sound of an acoustic. An upright bass, played purely acoustically, sounds more like a cello than an electric bass, just playing lower notes. I got to intimately know the sound of a cello from my sister practicing hers at home.

Some of my favorite electric bassists play sometimes using the heel of their right hand (if right-handed) to mute the string, in effect making the electric bass sound more like an acoustic. Listen to Joey Spampinato of NRBQ to hear what I'm talking about. Keith Richards loves his playing, enlisting him for the band he put together for his Chuck Berry documentary, and offering him the bassist slot in The Stones when Bill Wyman left. Joey turned down the offer, electing to remain with NRBQ, a much better band.

@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.