noble100
I don’t like organ, so forget 20hz (I went for that like a nut when younger).
I love Jazz, the low instruments are piano say 30hz, double bass say 40hz, many instruments no lower than 60hz. I know where each musician, each bass player is standing, where the trombone is, ...
the thing about Bass is, despite all the proven physics, listening to my pair of 37 lb 15" woofers each with magnets 7" thick,
they can control the bass as much as make it.
And, better controlled 40hz gives better controlled overtones 80, 160, 320, ... (overones is why analog sounds more involving than digital IMO)
Bass IS or, CAN BE directional.
this is a sweet listen, I just got a fresh copy for Christmas).
https://www.amazon.com/Double-Bass-180-NIELS-HENNING-PEDERSEN/dp/B005CJQR8S/ref=sr_1_1?keywords=double+bass+pedersen&qid=1579746066&s=electronics&sr=8-1
Keeping bass, or as another member here clarified, the bass overtones directional is why I do not like ports. If ports, front facing.
Now lets get to producing bass without roll off, keeping it at proper volume to adjacent, other instruments. This is where smaller woofers cannot perform.
Sooooo, if getting some decent bass, IN YOUR ROOM, from 6", then a pair of DIRECTIONAL subs, located adjacent to the mains, Not too big (that’s why I mentioned i.e. 10"), can extend a STEREO experience to relatively equal lower bass!!!!
A single, or too large pair of subs, poorly located because too big, will lose the potential for directionallity, and lose the directionality the overtones of those fundamentals provide.
You are hearing 40hz at proper level to other instruments, by itself perhaps not directional, but it’s 80 and 160 and .... tell your mind where that 40 is originating! Especially if the fundamental 40 is tightly controlled, thus big magnet, servo, ...