Upgrading sub to get a live feel.

Yes, thanks Tim. 

Hello Watcher,

     Great, just so we're on the same page you need to:
1. Complete your bass system by positioning your two SBs using the crawl system.

2. Order a pair of speaker stands for your JBL 4319s. I think the best place to search is eBay and google, just search for "speaker stands for  JBL 4319 speakers" on either.  You'll probably get even better deals on them if you'll accept used ones in good condition.  
     The exact height of the stands is very important.  You should measure A. the distance from the floor to the middle of your ears when seated at your listening seat. Then measure B. the distance from the bottom of one of your 4319s to the middle of the tweeter.  Take measurement A and subtract measurement B and you'll have the exact height required for the height of your speaker stands.  
     My assignment is writing a procedure for you on how to properly position your 4319s in relation to your listening seat and how to best adjust the volume, crossover frequency and phase controls on your subs for the seamless blending or integration of your two systems. 
     Just a heads-up, when you receive the speaker stands and it's time to follow the procedures, things will be easier if you can recruit an assistant to help you out.  Without an assistant, you'll be going back and forth way too many times between your listening seat and each sub and you'll probably wind up exhausted by the time you're done. 
     Send me a pm or post again when you order the speaker stands.

Thanks,
  Tim
    

I already have some speaker stands I can use and the current set up has the tweeter aligned to ear level.

Hello Watcher,

     Excellent, I'll try to complete the procedures today.  

Later,
Tim

I’m going to come at this issue from a different perspective. Fully agree with comments about deep bass being omnidirectional (or non-directional) in most settings. One failing of most audio bass setups (full range or subs), to me, is lack of control. It is relatively easy to get the tone of the bass notes pretty OK. But getting tight control of large woofer excursions is another. How often do people actually hear the timbre of the instruments producing the bass in their systems? One approach to sub-bass control is to throw mega-watts of power at it, probably better conceived as providing max feasible current to drive big bass flappers. Another, more elegant, approach is to employ motional-feedback in the bass amp circuitry. In this schema, the bass amp incorporates circuitry that senses the back-EMF produced by woofer coils when distortion begins to occur then, near-instantaneously, alters the output signal to correct and cancel said distortion. Audible result is to tighten up the bass output which, in turns, makes the woofer emit a sound that more faithfully replicates the original waveform captured in the recording. Loose, flabby bass is eliminated. Some self-powered subs employ this method. The old (1970’s) Phillips motional feedback speakers (full range self-powered bookshelf speakers) also did this with impressive results. In my system, I use one channel of a Streets 950 power amp w/ only 110wpc --equipped with an extra binding post for use when motional feedback is desired-- to drive a single Clark Contra Bass sub (2 x 12" cones wired out-of-phase and bolted face-to-face, downfiring), to produce deep bass in a smallish room that outperforms anything I have heard in a showroom anywhere. The Clark actually sits next to my listening seat. No one can tell the bass is coming from 2 feet away to one side.
One more thing helps with tight sub-bass control. Minimize speaker cable impedance. A long-ago TAS article introduced me to #4 welding wire. Thick, black, fugly, but cheap & flexible & all to terminate with big copper spade lugs. Works. ’Nuff said.