My experience adding subwoofers to 2 channel

Following doctrine gets you absolutely no where. Good for you. I started messing with subs because I knew theoretically they should be a huge benefit particularly with a planar speaker that has limited excursion capability and is a dipole. I would be happy to send you a picture of the whole array. It is set up on a radius from the listing position forming a segment of a circle. The subwoofers are position so that the face of the driver is in the null of the ESLs which is directly to the sides. Dipoles have a figure 8 radiation pattern. Even without room control this works pretty well but without digital bass management, given my experience you are sunk. All the amplifiers are downstairs on a shelf up against the ceiling right under the speakers. The ESLs are 3 feet from the front wall and the subs are positioned so that their drivers are right up against a wall two between the ESLs up against the front wall and two to the outsides up against the side walls. Acoustically these subs are acting as one big driver 16 feet wide forming a linear array of infinite length. Linear arrays like the ESLs do not radiate to the sides, up or down. This is a huge benefit preventing as least 4 of the primary reflections in the room. The result is that no matter where you go in the room except right up against the walls the bass output at any frequency is the same. No standing waves that you can hear. You can not tell there are separate subs in the system. the presentation is one big whole or rather all the speakers disappear. The only disadvantage is that you can tell exactly how bad most recordings are engineered.

Hello mijostyn,

     Very unusual and interesting.  I think I understand your setup but I'd love to see a picture.  Or you could fill out the system section on your profile and upload pictures for future reference.

     The way I understand it, you're main speakers are ESLs (Quad ESL63s or possibly even a newer model?) that are positioned about 3 feet out from your front 16 ft. wall.  All four of your Dayton subs have front firing 12" drivers that are facing the walls, 2 between the ESLs and 1 near the front of each L+R side wall, perpendicular to the side of each L+R ESL speaker (the null area) and facing the wall.  Am I correct?
    My subs are all front firing subs with the drivers facing the wall but have 10" drivers as opposed to your 12" drivers.   I also have 2 subs along my front 16' wall with one positioned behind each of my 6 x 2 ft. Magnepan panels that are straddling a large hdtv, about 8 feet apart and 4 feet out from the front wall.  There's also a sub along each of my 23 foot side walls with the left sub about 1 ft away from the left rear corner and the other about 2 ft away from the right rear corner.  My listening  seat is in the middle of the rear 16 ft rear wall and in between these 2 rear subs.       Even though there's a sub on each side of my listening chair within 8 ft away, I never perceive the bass as originating from either one (no localization of bass).
      You're using a linear bass array configuration and I'm using a distributed bass array configuration, but it sounds like we're both getting very similar high quality performance results; accurate, detailed and extended bass response with no standing waves you can hear and seamless integration.
        I'm interested in your system and was wondering about your room dimensions, what you use for bass management and whether you use it for music only or ht, too.


Thanks,
  Tim

Tim No, Right now I have modded out Acoustat 2+2s. Quads are not linear arrays. Full range linear arrays have to extend from the floor to the ceiling. I am on the brink of getting SoundLabs Majestics 845s as I have 8 foot ceilings. Between the speakers is a theater screen. The sub drivers are front firing. The inner two actually face each other with three feet between them. This gets the driver closely coupled to the front wall. 
The outer subs are against the side walls facing forward. Their drivers are closely coupled to the side walls. The main speakers are angled towards the listening position. A line extending through the sides of the speakers will intersect the faces of both subs on its side.
Your Maggies are linear arrays down to about 150 Hz where they convert to point source. In order to get the full linear array effect you would have to cross to the subs no lower than 150 Hz. But then your subs would have to be closer together, about 3 feet. I wish Maggie would make a speaker with 8 foot woofers. It would make life much easier.
I hope your listening position is not right against the wall. If it is move it forward a couple of feet. Sound waves are very slow. You have two subs back there with you and you hear those fractionally before you hear the ones on the front wall. This will smear transients. You want to hear all your subs at exactly the same time. You also have dipoles so you want all your sub drivers in the null zone beside each speaker. If your TV is mounted on the wall up off the floor you can put two woofers between the Maggies facing each other right up against the wall under the TV. Now If you try crossing at 150 Hz the subs will have to be no farther apart than three feet. So you would array them across the front wall and up the side walls three feet apart.You do not want to put a sub behind the Maggie. It will cause weird interactions with the woofer panel which is why I locate them in the null zone. With your woofers 3 feet apart they will all act as one driver and you will hear all of them at the same time. If you move them further apart and cross lower, 100 Hz cross puts the subs 5 feet apart you will have a very important segment of the bass drop into point source mode and that segments volume will drop off rapidly as you move away from the speakers. I wish Maggie would make their big speakers 8 feet tall, actually 7' 10".
The room is 16 X 60 feet sort off. The system spends much more time playing music but it does TV and Theater duty. I have no need for rear speakers or a center channel. I have a digital preamp which includes room control and the best bass management ever made. I can adjust cross over points and slopes on the fly. I have up to 10th order slopes and the cross overs can be adjusted in 1 Hz increments. I also have complete control over levels. Thus I only need passive subs and I am much happier choosing my own amps. The only unit that comes close is the Trinnov Amethyst. There are stand alone digital bass management systems out there. I believe DBx makes one. Sanders uses it in his speakers. There's another one who refuses to make his speakers taller. Talking about bad recording engineering. I was just listening to Neil Young's Harvest. The snare drum is right in your face and Neil and his guitars are like 50 feet behind. Pretty surreal.

Sub integration for proper bass is not the way...
Note the word proper.

Change your speakers or accept them for what they are.

Jmac:

I have been using a HSU ULS -15 MK2 , doing double duty for music and HT, for about a year. I find it very well built and performs very well. With all the talk of multiple subs I am tempted to get another one to see how much better it could be, but so far every time I think it out loud, the wife gives a bad reaction. But you know what they say, its easier to get forgiveness than permission, so one day it might just apare.