There's a lot more bass in a 6.5" driver than most of you think

french_fries:" IMO outboard Subs are for movies anyway, unless your room is enormous."

Hello french_fries,

       I suggest that your belief that outboard subs are only for movies, is a very clear indication that you've never heard a high quality 2-channel music system with well integrated subs or that you lack the knowledge to properly implement subs seamlessly into your own system, perhaps both?
      My intent is not to overly offend you, my intent is to suggest that you may not be aware of what you're missing.  It's been my experience that  the main characteristics that differentiates listening in person to music played live (I'm referring mainly to a smaller type settings and not to large arena type settings) and listening to music on most home audio systems, are the the accurate, detailed and highly dynamic reproduction of the bottom 2 octaves of deep bass (about 20-32 Hz)that is experienced as being felt as well as heard.
     Sure, the bass can still be perceived as very good without the bottom 2 octaves but it's not the same powerful, dynamic experience that is felt as well as heard and closely resembles the deep bass of music heard live and in person. 
     There's also the issue of, even if one utilizes large main speakers with large woofers (or even multiple large woofers) and the speakers are rated as having accurate deep bass extension down to about 20 Hz, this does not mean this deep bass is necessarily perceived at your designated listening seat.  This is due to what I mentioned earlier in this thread; 
basically that the main speakers are precisely placed in the room with the midrange/treble transducers positioned in relation to the listening seat for very good midrange, treble and imaging performance.  The major problem is that the woofers are affixed in place in the same cabinet, typically below the midrange/treble speakers, and cannot be independently positioned in the room and in relation to the listening seat which is required to optimize bass performance at the listening seat. 
      It's highly unlikely that the optimum performance room positions for the main speakers' midrange/treble and bass drivers, in relation to the listening seat, all just happen to be at the same exact floor spot in the room, with all speakers vertically aligned in the main speakers' cabinets. Outboard subs, being capable of being independently placed in the room and in relation to the listening seat, are ideal solutions for attaining high quality bass response performance at the listening seat.   
     Using large speakers with large woofers and the midrange/treble drivers in the same cabinets, there's no guarantee that room bass modes (causing bass peaks, dips and nulls) won't exist at the listening seat. Outboard, independently and properly positioned subs will guarantee there are no bass modes at the listening seat.  
      French fries, if you'd like I can describe exactly how to utilize 2 subs in your system/room to attain very powerful, dynamic, detailed, fast, smooth and natural bass performance at your listening seat that integrates seamlessly with whatever main speakers you have.  If you're open to using 3 or more subs, I can describe how to get near sota bass performance throughout your entire room, not just at your listening seat.

Let me know,
      Tim

’Cutting Edge Design’ starting with your existing 6" drivers.

look at the directional pair of monster woofers at the bottom of these 22k beauties:

https://www.audiogon.com/listings/lis9i01e-evolution-acoustics-mm2-full-range?utm_campaign=Saturday_Email_20200125&utm_content=saturday_email_20200125&utm_medium=email&utm_source=zaius

Your existing mains, (6" driver or two): Probably in cabinets or stands to get the tweeter at seated ear height. No way to get a directional pair of woofers matched with their l/r origin.

Cut your tall enclosure, reseal the bottom, put it on a self powered sub-woofer, same l/r. Or, toss the stands, put them on the pair of sub-woofers.

Of course you need to figure out vibrational connection/isolation, but that’s easy isn’t it. Hah.

Mains with tall cabinets ’shortened’ will have less volume, BUT, the 6" no longer trying to produce bass, so, larger volume, or disruptive or non-directional port not needed.

As I Punned, ’Cutting Edge Design’.

In Chicago audio show (2016) I have heard, rather small tower speaker, from Penaudio (Serenade) with two 6" woofer, and it was unbelievable bass !

Today is a paradox for audio systems.  Back in the day when sub woofers only existed in passive systems with large cabinets we were still happy. Purests in that time of the late 60s, 70s, 80s tried to sell systems with no tone controls as they do today.  We were told it would "color the sound"   people liked the loudness, bass and treble controls.  Today if you want bass you are told to buy a sub woofer after spending a anywhere from $500 -$1000 for a pair of speakers.  Guess what? The sub woofer colors the sound. 
I have a relative the worked as a speaker builder for paragon a acoustics back in the 80s. He built himself a pair of 6" driver towers. They used 6" woofers. Why?  They not only got the bass below 30z, but were two way because the smaller cone could also get good midrange. Also, smaller drivers are easier for a power amp to control because of less moving mass. They are fast a d respond quicker to changes in music dynamics. Also because of that, less distortion.  No sub was needed. They still sound great

     I had some computer hardware issues that are now rectified but I was unable to continue following this thread as closely as I was over the past 3 days.
     Catching up today, I was disappointed to discover that a few posters have been attempting to debate some facets of how deep bass soundwaves behave in smaller domestic rooms and how our human ears and brains detect and perceive these deep bass soundwaves as deep bass. I just want to restate and remind thread readers and posters of a few things that have been scientifically proven by acoustic experts and are generally considered to be true by the vast majority of them. In other words, facts that we should not be wasting our time and effort by debating or misleading others about:

1. The vast majority of humans are unable to localize bass sounds/tones below about 80 Hz. This means an inability to determine where these omnidirectional deep bass soundwaves/sound tones are originating from and, therefore, means there’s no need or sense to operating deep bass drivers (including subwoofers) in any other mode than mono since there is no such thing as stereo deep bass. This is why virtually all commercial music recording engineers sum the bass at about 80Hz or below to mono on their recording mixes. Even if a system were configured for stereo bass below 80 Hz, it would be useless since there’s virtually zero music source content material to play on it. If you doubt this, try to name even a single exception to this statement.
      It’s very important to note, however, that most individuals will still be able to perceive the deep bass sounds/notes as directional and properly localized within their system’s soundstage illusion. That is, deep bass sounds/tones will be perceived as coming from the proper instrument position within the stereo soundstage.
      This is due to the fundamental deep bass tones, being below 80 Hz and coming from the bass drivers, not being directional but the overtones/harmonics of the fundamental bass tones, being above 80 Hz and coming from the main speakers, being directional and our brains being able to associate the directional overtones/harmonics with the omnidirectional fundamental deep bass tones and thereby perceive specifically where in the soundstage the deep bass tones are coming from.
     I utilize 4 relatively small, 12"x14.5"x28", subs with 10" long-throw aluminum drivers in a distrbuted bass array (DBA) in my room operated in mono mode from 20-40 Hz with my main speakers run full range with bass extension down to 35 Hz. I can attest that I definitely perceive the deep bass as coming from the appropriate soundstage location. 
     I not only perceive the increased bass extension and dynamics as seamlessly integrated within the soundstage illusion in my room, this high quality bass also provides the perception that this soundstage is wider, deeper and more open with individual images that are more solid, stable, palpable and natural. I’m able to focus in on individual mages/instruments and follow their musical notes, beat as well as volume and pitch changes. This high quality audio reproduction is easy to perceive in the midrange and treble frequencies, but extending this perception all the way down to the deepest bass frequencies is unique in my experience and something that really enhances my involvement and enjoyment of all the music I play.

2. Humans can’t even perceive the exitance of sound tones in their rooms until the complete full cycle (fully formed) soundwaves exist in the room to be detected by our ears and processed as a perception of sound at a certain pitch/frequency, volume and duration. It also takes several full cycle soundwaves to be presented into the room for changes in pitch and volume to be perceived.
     This is simple, matter of fact and routine with the relatively short and highly directional midrange and treble frequency soundwaves in a room but becomes more complex, less matter of fact and routine with the relatively long and omnidirectional frequency soundwaves in a room. As I’ve stated previously, a 20 Hz soundwave is 56’ long, a 30 Hz is 28’, a 40 Hz is 19’, an 80 Hz is 14’, a 500 Hz is 2.7’, a 5,000 Hz is 2.7", a 10,000 Hz 1.4" and a 20,000 Hz is a fraction of an inch long.
     It’s easy to see from these soundwave length examples that as bass frequencies get deeper, their complete full cycle soundwaves at some point may exceed the physical dimensions of an individual’s typically sized domestic room and inevitably it requires the soundwave to reflect off of at least one room boundary (floor ceiling or walls) for the entire soundwave to exist in the room. 
     These long deep bass soundwaves continue to reflect off room boundaries until they’re are absorbed, diffused or run out of energy and invariably collide with other reflecting and more direct bass soundwaves which cause bass room modes. These room modes are perceived as specific room spots at which the bass sounds exaggerated, attenuated or even non existent. Without using at least two independently and properly positioned deep bass drivers reproducing frequencies below about 80 Hz in a room, there’s no ability to ensure your listening seat position is bass room mode free.

     The above are proven facts and realities that need to be accepted and taken as givens in any meaningful discussion concerning the attainment of very good bass response performance in any room and with any pair of main speakers. If you just positioned your main speakers at specific room spots, in relation to your listening seat, to optimize the midrange. treble and imaging performance and are also getting very good bass performance there as well without at least a pair of external and independently positioned subs, then consider yourself very lucky since you just happened by good fortune to avoid any serious bass room modes.
     Of course, there could also be bass room modes at your listening seat and you’re just unaware of them.

Tim