My experience adding subwoofers to 2 channel

Avanti I agree with you almost entirely. You do have to with your rooms acoustics physically but particularly when it comes to bass there are limits as to what you can achieve. You can not achieve SOTA bass without digital bass management and subwoofer control. First you have much more control over x-over frequencies and slopes. In the digital realm there is no phase shift. Then you can adjust the frequency response of the sub woofers so that they are up 3 db at 20 Hz. Tolerably sized sub woofers start rolling off at around 60 Hz and are down 6 to 9 db at 20 Hz especially if they are not closely coupled to a wall or corner.
With enough power this can be corrected with startling results. Putting on a 20 Hz tone is a riot. It sounds and feels as if it is coming from the whole house and everything buzzes and rattles. Dishes, silver ware, picture frames, the toilet and my teeth. At 60 Hz I can definitively localize the sound and the symphony of rattles stops around 40 Hz. 
Tim, the best speaker control (room control) measure each speaker independently and adjusts each speaker independently. The problem with sub woofer systems is that they ignore the satellites.     

Oh and Tim I have used subs in every configuration you care to think about and have been using 4 subwoofers for......25 years anyway.
I am glad you like your system and that it works for you. Unless you are extremely lucky your bass below 40 Hz is for certain a mess. Lord knows what it is doing up to the x-over. If you send me pictures of your room and system I would be happy to fix it for you. I am working with another forum member who has Acoustats and was unhappy with his DBA system. Of course he is use to a level of detail and imaging that you can't get out of dynamic drivers so the muddiness of a DBA system would be more offensive to him. I have not heard back from him yet but I think we have finished adjusting his system.
I don't have to use a tape measure myself. All I do is set up a microphone and tap the measure button which is displayed on my PC. If I am happy with it I tap the enable button and all the volume, delay and frequency adjustment are made in a few seconds. Then I overlay my own response curves and we are good to go. No guessing and I am not relying on anybodies hearing not even my own. There is no way I could get bass this good by playing around and depending on hearing. You can't either especially with sub woofers thrown all over the room.

noble100 says of mijostyn:

Incorrect, wrong and you're mistaken. Millercarbon absolutely knows you're wrong because he had the intelligence and cajones to give it a try.

Yup. And thanks. Finally got the Rosewood veneer on and finished. 

I believe the root cause of our disagreement over the effectiveness of 4-sub distributed bass array systems is your lack of experience and familiarity with them.

For sure. Demonstrably so. Thanks again.

Ok, DBA SWARM subs are absolutely the only way to go I wish I had the cojones to take my 200 lb subwoofers and their 2000 watt amplifiers and toss them up in the air to let them play wherever they land happily ever after. But I am an old man and to stupid and weak to lift these things never mind throwing them up in the air.
I'm sure you guys are on gluten free diets. You need to switch to now to Keto!

Hello mijostyn,

     I’m running all 4 subs in mono with a xover frequency between 40-50 Hz and a filter slope of 12 db/octave, usually configured for a 40 Hz xover for music and 50 Hz for ht. My main speakers are Magnepan 2.7QRs that each have a 620 square inch planar-magnetic dipole bass section but they only extend down to 35 Hz. I run these full range with a pair of D-Sonic M3-600-M mono-blocks rated at 1,200 watts each at 4 ohms. This combo produces very accurate and high quality bass on their own but I added the AK Debra 4-sub DBA system for added bass impact and increased dynamics.
     Since the 2 bass sections only extend down to 35 Hz, I don’t consider them extra subs in the room but I do think they help on the overall bass quantity and quality in my room; for example, hearing the initial pluck of an upright bass’s string followed by hearing the deeper bass produced by the body of the instrument and finally the natural decay.
     Subjectively, I perceive the bass as very accurate in tone, detailed, extended, dynamic, smooth and natural with an impact that is felt as well as heard. I don’t detect any bass muddiness or have the sense that the bass is too slow, lagging behind or disconnected from the rest of the reproduced spectrum. 
     However, I’ve never had the in-room frequency response measured but I would be very surprised if it didn’t measure well.  I do have pictures of my room and system on my profile if you’d care to look and my room is 23 x 16 feet with 8 foot ceilings.


Thanks,
Tim