One sub or two or none?

The question is-one sub or two-or none? Some purists may say E-Gads man-NO SUBS. Each to their own. Since I became aware, I have liked a lot of bass. It was always a test to see what speaker put out the most low frequency. I don't know why I didn't think of the "sub bass" idea long before it became popular. Guess it's like the invention of the wheel-once someone came up with the idea, everyone said "of course." Anyway, I take my sub use on a more subtle basis now. Some well produced LP's/CD's have all the low frequency you may want; sadly others, the bass was rolled off for different reasons. Back in the day, the bass was rolled off on rock because many didn't have the equipment to reproduce it. After all, most listened to AM radio. Even when FM became the modulation of choice, the bass was rolled off around 80 hz or above. On classical recordings, the full frequency was available for all to enjoy. Good for them. Anyway, I have tried two subs, then one. I made a couple subs that incorporated two JL 15 W-1's, pushed with a 600 watt RMS amp. I even connected a dbx sub-harmic synthesizer to extend the bass. The sound was good, but lacking. I finally purchased a JL Fathom 113. Finally, I had all the bass I wanted at the proper frequency. I set the crossover to 40hz and below. Then it was where to place it. Jim Smith's book How To Get Better Sound, says two subs are better than one. In my experience, one is as good as two. In articles written about two subs, some say to stack the subs to reinforce the bass so they don't cancel each other out. Even then, you have to be sure they're in phase. I tried one positioned just to the left of my right channel speaker, then in the center. I have to say the center gives the best sound for me. OK-some are saying Hello-that should be obvious. However, most say low frequency is not directional, so placement isn't critical. I can tell a huge difference, mostly with LP's when it's placed in the middle. Before stereo, theaters achieved better sound by placing the low frequency speaker in the middle of the theater. I'm thinking this is still a good idea. Partly because you cut your speaker cost in half and partly because two are not better than one. This opinion may be worth what it cost you. Try it yourself-that's the ultimate test.
The way I have heard it explained, you should position the sub at your normal listening position. Then while it is playing, walk around the room and listen for where the sub's output sounds loudest. Then move the sub to that position and you're done...

Looks like you have tried all of the things suggested about using sub's. As I did. The only sub set up's that ever worked for me were rolling the main speakers off much higher than 40 hz and placing a single sub between the speakers. Elegant and simple. Maybe not the best sound in an absolute sense however. Next was using a sub for reinforcement below 40 hz was crossing the sub off below 60hz (you would make this decision judged by the crossover slopes) and running the main speakers full range. That had the better sound and the woofer placement was controled by the actual bass FR (flat or specific FR boost, depending on what you want to get.

FWIW, ultimately I found that simplicity of set up (i.e. optomized main 2 channel two way speaker set up) was, for me, going to be superior in the long run UNLESS there are nulls and nodes (at the listening position) which are created by the set up and one need subs to help flatten the FR. 2 subs are usually more effective, at least that gives you the opportunity to be more effective by placing them where ever they work because they are asymetrical to each other, the main speakers and room dimensions. They don't have to be symetrical. And in my experience being able to play with the phase relationships can be a good thing if your crossovers allow.

But for me in the long run that was all too fussy and kept my attention too much on acoustics and not so much on the music. My subs are in the attic and I use floor standers +/- 3db to 28hz. When there IS deep bass in the recording I get it. What I don't get is bloat or boom and I've found that I prefer that. One less thing to think about.

BTW, less you want to just give up, setting up a system with or without subs is NOT a walk in the park. It can take an average audiophile years to really optomize a system set up. There is so, so much to learn and it really does take a lot of listening time to do it right. Good luck.
I'm not a bass freak, but I run 2 M&K KX 10's 8" 125 watt powered subs in a 12x14 bedroom. I use Lipinski L 707 monitors. I can tell a difference using either one or 2 and 2 sounds better. I don't play music very loud and really have no big need for a sub, but sometimes depending on the music it's nice to have the options of none 1 or 2.
Handymann I used to use 2 REL Stentors (but had reliability issues with them) so I went to one JL Fathom 113 as you did and tried it in the right corner then the left corner and finally the center of my room and viola the center worked the best and I couldn't be happier. Smooth yet powerful and when there's no bass there's no sound from the sub.

(dealer disclaimer)
Two. I've worked on that solution over ten years ago and after many, many hours of tweaks, found that two, with proper placement does the trick. I run them with full range speakers PROAC. So, look into two. I have NHT units with outboard amps. Oh, the joys of improving your listen are endless!
@Buconero, whats the placement of your two subs? I recently incorporated one sub in my system after going to rmaf and realizing that full range audiophile grade speakers are actually full range. If I could afford $15,000 Silverline Boleros that play down to 28hz, well then I guess I wouldn't need a sub either. Until then, I am sold on a good sub to pick up where my speakers roll off. Btw, I'm using paradigm studio 20's v.5, and an svs sb 12-plus and I love the sound I've acieved. I run the paradigms full range, place my sub in the center of the front wall (after originally placing it in the front right corner of the room) and it sounds great!
Actually, I agree with all of the observations here! On the question of using one or two subs, the room characteristics are important. In my experience, it is not just the presence of low frequency, but the also how the room is pressurized by the musical activity in the lower ranges. Since my full-range mains (Zu Druid) are somewhat light on the bottom, I've tried all of the above methods and am now most pleased with two subs. Incidentally,each placed just outside the mains and perched on low Lovan stands (this eliminates all hint of bloat and dramatically improves imaging for a fine, articulate bass). After experimentation, I've reverse-mounted and aimed the drivers toward the ceiling! In this way, the room is beautifully pressurized by two columns of low frequency sound. Standing waves are nearly impossible to find and the presentation is so very relaxed and natural. Being something of a diy person, my "twins" re-built M&K Volkswoofers. There is a top-to-bottom seamless presentation. Cross is set around 40Hz. The front end is exclusively tube gear.