Are big subwoofers viable for 2 channel music?

    I agree with millercarbon and brotw, DBAs  excel at providing very fast, smooth, detailed bass throughout the entire room, not just at a designated LP.  The bass is also capable of being as powerful and dynamic as the music or HT content calls for because there's 4 of them operating in mono as a collective group.
     Based on my experience utilizing a 4-sub Audio Kinesis Debra DBA system for the past 5 years, the main benefit is the perception that there is a complete absence of bass peaks, dips, nulls, muddiness, boominess and ringing.  I consider the bass quality as near state of the art in my room/system and cannot identify any actual bass deficencies.
     As I understand it, the benefits of utilizing multiple subs begin to be realized with the deployment of 2 subs in a given room, especially when both subs are optimally and precisely positioned in relation to the LP.  It's also very important that the volume, crossover frequency and phase controls are optimally set on each sub for these benefits to be realized.  
     Based on my prior usage of 2 self-amplified subs in my room/system, I would describe these benefits as the beginning of realizing the benefits of using a 4-sub DBA system.  The bass begins to sound faster, smoother, more detailed, more powerful and dynamic, better blended with the main speakers and very good overall.  My experience transitioning to 4 subs resulted in even further improvements in all of these bass qualities and the overall bass quality improved from very good to what I consider near state of the art.
     To answer brotw's question about whether one can attain an approximation of a DBA's bass quality performance utilizing just 2 higher powered subs with room correction, therefore, I believe the answer is a qualified yes, depending on whether an individual is satisfied having this high quality bass restricted to a single designated LP in the room. 
     However, I'm less convinced of the positive effects of room correction hardware/software and room treatments on overall in-room bass performance.  Of course, this could be the result of never utilizing room correction, and only recently utilizing room treatments, in any of my own multi-sub room/system configurations. I was concerned about adding bass room treatments recommended by GIK after a room analysis, 2 stacked TriTrap bass traps in all 4 corners and some other 5.5" thick bass trap panels spread about, but they've had no negative bass effects in my room.
     As to room correction hardware/software, I suspect that having ruler flat bass response in a room may not sound as good as we might expect.
     So brotw, my best answer to your question is a definite...... maybe.  

Tim

I suspect that having ruler flat bass response in a room may not sound as good as we might expect

Thanks for the sharing Tim. I believe room correction has the benefit of improving the tonality of the rooms bass response at the LP. Of all the speakers and amps that have made their way through my listening room, not one did not benefit from dsp. Music sounded more coherent and live with tighter bass and imaging every time I flipped on the Dirac filter. The mixed phase filters are great, and perhaps they are correcting the speaker crossovers and room all in one.

That being said, dsp is no silver bullet. Can't fix reflection points nor extended decay from a "lumpy" single sub bass response, only DBA appears to do that.

One area of interest include using room correction to help integrate dual subs better after level and phase matching to the mains at the crossover frequency. Another curiousity is seeing if using bass management in my newly acquired Parasound P5 produces better sound by unloading my tube integrated LM508ia from sub 50-80Hz duty driving Tekton DI's and simultaneously reducing the SBIR effect from the mains below 50Hz. That falls into the "to high pass or not" category.

Xovers like the JL CR-1 potentially disturb the pristine signal coming out of really nice preamp, then again, the same is said of dsp. I have neither so I'll dip my toes in the water with the P5 which allows funds for a pair of good subs. 

brotw: " I believe room correction has the benefit of improving the tonality of the rooms bass response at the LP. Of all the speakers and amps that have made their way through my listening room, not one did not benefit from dsp. Music sounded more coherent and live with tighter bass and imaging every time I flipped on the Dirac filter. The mixed phase filters are great, and perhaps they are correcting the speaker crossovers and room all in one. "

Hello brotw,

     I think it’s best that I just accept your claim as fact that room correction/DSP/Dirac have had positive effects on your systems. I also realize individuals are unlikely to improve their system’s performance without having the sense to learn from the experiences of others and taking the initiative to actually audition the promising suggestions in their own systems.
     However, I’m a bit confused about exactly what component you’ve been utilizing in your systems that contains DSP/Dirac filtering capability, can you let us know?
     My prior preamp was the Parasound Halo P5 with bass management, so I am very familiar with that unit. Imho, it’s a good preamp with a very neutral sonic signature. I now use a Levinson 326S preamp in my system. I didn’t see a purpose in having 3 bass management systems, one with controls on the back of the P5, one incorporated into my Oppo 205 Bluray/CD/SACD player and the one with controls on the front of my AK Debra 4-sub amp/control unit. I also liked the improved tonal quality and more 3 dimensional sound stage I perceived with the 326S in my system.
     However, I think the P5’s bass managent could prove very useful in your system, especially if used to reduce the bass duties of your Line Magnetic 508ia SET tube class A 48w/ch integrated amp.
     I believe your best solution is utilizing a pair of good quality self-amplified subs in your room. You could connect both subs to your P5, set the P5’s bass management controls so that all bass frequencies below about 60 Hz are sent to the subs and all frequencies at or above about 60 Hz are sent to your 508ia. I think this would likely eliminate your 3-5db suckout near 50 Hz and improve the midrange, treble and stereo imaging performance of your 508ia and main speakers combination.
     You could then optimize the overall system performance and balance by making small adjustments to the low and high pass crossover frequency control settings on the P5 by ear and preferences.
For best results, I recommend precisely locating each sub in your room, and in relation to your LP, sequentially utilizing the ’sub crawl method’. You can google it for details.

Tim

What I'd like to know is whether a 4 smaller sub DBA has diminishing returns over dual larger higher powered subs when room correction is employed

IMO/IME its the other way around. But if you have a DBA, then when you apply the room correction it'll work a lot better!

But if you have a DBA, then when you apply the room correction it'll work a lot better!

Yes, all things being equal, the more subs the merrier.

 I think it’s best that I just accept your claim as fact that room correction/DSP/Dirac have had positive effects on your systems.

Tim - I'm using Dirac live on PC. Sound quality improved a good deal with the SOtM txusb-exp card, RUR, and curious cable feeding a Schiit Gungnir. The W4S dac-2 when paired with Dirac was too sharp/forward and when paired with class D amp - unbearable. Now the sound is more tame. Using 244 panels and tritraps from GIK which helped out mostly above 80 hz.

I've always been a bit skeptical and suppose somehow the dsp is ruining something. When swapping new amps, speakers and preamps, the unique sonic characteristics of new components have always shown through even after calibration. It's not too unlike the DBA decay effect where certain sonic characteristics do not reside with the initial CW signal. Send a CW signal through a system, and each component imparts it's unique harmonics and noise. Speakers especially retain their flavor from inert  to lively cabinets and drivers, both of which will impart higher order harmonics from a CW signal during cal, but it is only the CW signal that is phase and mag corrected at that instance in time. The broadband response to the CW excitation remains and is uncorrected. I'll probably always periodically test feeding the Dirac device and then the dac directly too make sure I'm not leaving something on the table.

The P5 so far sounds as you say, neutral, and likely has a better attenuator than the LM508 integrated. Inevitably it is just a stepping stone. Wanted to spend $3000 on a higher quality preamp but figured the P5 with dual subs for similar price would make more of an impact.