My experience adding subwoofers to 2 channel

I have known Duke LeJeune for quite some time now, even owning his Jazz Module speakers for several years and using his speakers in my exhibit rooms at audio shows. Earl Geddes was his mentor and while Duke manufactures box speakers, he has a pretty good understanding of ESLs having used the original Quad ESL in his research (the speaker that replaced my Jazz Modules) and being one of the more prominent Sound Lab dealers. I think he has a good grasp on sound dispersion and how to maximize it. In addition, I should mention I had never been keen on using subs in my system even though I was well aware of Duke's initial work developing the Swarm.

The last show I exhibited at with Roger Modjeski we used his ESL speakers which by default had to have subs since they only went down to 100 Hz. Roger designed a sub with an 8" driver in a 0.3 cu. ft. sealed box (air resistance) and used two to compliment his panels in a bi-amp set up with the Beveridge RM-3 crossover he designed for the 2SW speakers long ago. After hearing this I followed suit but decided I would expand to 4 subs to replicate the DBA of the Swarm. For the last few years I have enjoyed this set up with both the Quad ESL and now my modified Acoustat Model 2 speakers.

However, I was intrigued enough by mijostyn's set up that I contacted him and he sent me a photo so I could visualize it. I would like to add that I was not unhappy with my DBA set up, but since he was also using Acoustats (they are essentially a bigger version of my Model 2s) I felt this was worth a try. Over the past few days we have been communicating and he has helped me tweak things to get the set up just right. I have been listening on and off since last evening and have to say I am impressed by what I hear, the primary difference being what I feel in the low end. So I would like to thank mijostyn for his contributions to this topic and help getting me there. I will try to post more on this as I continue my listening.

Hello clio09,

     I'm very impressed with mijostyn's linear/line array sub system and I've never even heard one in a home system, although I'd love to.  
     I'm also very interested in in your bass system build with your Acoustats that mijostyn is very kindly assisting you with.  I'm also very happy with my DBA system but would be tempted to try it if I had the clean slate of a dedicated room.  My combo music and ht room is also my living room.  My 4 subs are currently very inconspicuous in the room which I think is very cool, because you only hear and feel them when there's prominent bass content on music and ht being played, and my wife can live with.
     As I understand line array bass systems, the subs would be aligned across the front wall of the room and my 6x2 foot Magnepans would also be positioned about 4-5 feet out from this front wall.  I'd be okay with it but my wife's opinion of this in our living room would likely be expressed by a sturdy frying pan smacking my skull. 
    But I wish you only the best on your build clio09 and hope you and mijostyn enjoy your linear array bass systems very much.

Please do post updates.
Thanks,
  Tim

My subs were built a while back, mijostyn helped me set them up for optimal performance in the line array. His subs have quite a large footprint, as do his speakers which are probably the best Acoustat model in my opinion. They line array per mijostyn is actually a semi circle as opposed to all of the subs being against the front wall of the room. A very interesting set up and one that does require some attention to detail. I appreciate mijostyn’s patient with me.

In my room the DBA did work well for my needs, and it wasn’t a difficult system to set up. My only nit was that my room constraints didn’t allow me complete freedom to place the subs anywhere I wanted. The sound was quite good though. I am embarking on building 4 new subs using a 10" driver and look forward to going to the audio show in Long Beach to hear Duke’s Swarm in person.

Hello Tim,
 “ I just sent you a personal message. You should see a 'dialogue bubble' icon on the upper-right side of your screen, next to the 'shopping cart' icon. Just click on that and my pm should show. Click on my pm and I think you can hit reply and attach your video clip before sending.
 I'll re-post on this thread once I receive it.”

i do do not know where to locate ‘dialogue bubble ‘ icon.
khiak

Thank you clio. You said something that is very important (to me at least)
Bass is not just about hearing. It is about feeling. Part of the rush of a live performance is the visceral sensation you get from accurately projected lower frequencies. This is not easy to do in the home environment. Very few systems do this well but it is vital if you want to feel as if you are at a live performance. Even with string quartets the cellos go low enough to feel to to mention the transients caused by banging and thumping on this that and the other. The "visceral" range is (I'm guessing) from 150 Hz down.
Tim, Magnepans are great speakers. If you remove enough bass from them you can get them as close as 28" to the front wall. Just put some acoustic foam directly behind them. There is this thinking that you have to keep the cross over as low as you can to prevent the woofers from getting up into your mid range. It is easier to blend in with the satellites at higher frequencies and this is particularly true with dipoles which you have just like clio. He crosses over at 100 Hz, not sure about the slope.
Many cross low because they are trying to avoid a high pass filter on the satellites which is also mistaken. Removing the low end from the satellites cleans up the midrange and increases your power handling. You can put a simple 6 db/oct high pass filter on your Maggies simply by putting a cap across the input of your amps the value depending on your input impedance. The equations are on line. 
The reason clio is now feeling his bass is because his subs are now functioning as one driver and the arrival time (phase) is the same across the entire room. His Acoustats are now part of that linear array in the crossover zone. He is now getting his bass as one unified whole not the random output of various drivers around the room. Placing speakers around the room will smooth out response variations but because the speakers are more than likely 1/2 wavelength of the highest frequency you want them to carry apart, they are acting as individual drivers and transients are being smeared. This may be another reason DBA people want to stick with lower x-over frequencies. You can put the subs farther apart and get away with it. A SWARM system can work under certain circumstances. Low x-over points in smaller rooms. Once you pull your cross over up and get into a larger room say 15 X 20 you get into trouble.
What you hear is important. But with bass what you feel is more important.