Why the fascination with subwoofers?

Dear @noble100  : I did not knew which is the crossover frequencies in your 2.7qr and now I find out:

Low-Pass 12dB/octave @ 650Hz

Band-Pass 6dB/octave @ 500Hz-950Hz

those " numbers "  makes me to tell you it's almost and " emergency " and your speakers are " shouting " for that high-pass filter ! !

Rigth now you have good bass and you can have an exceptional mid/high ranges in your system adding that high-pass filter.

IMHO it's a must that you do it because the IMD distortion levels is to high and in a very wide range up to over 900hz. It's a serious compromise to leave it that way.
A compromise is that you can have a better  quality " equilibrum " with your bass range if you can achieve better quality levels in the mid/high frequency ranges. As I said before is up to each one of us.

Btw:   you said that the CD's and other digital sources you own/use does not goes below 20hz. Maybe you are rigth but always exist a dude because your system does not have the ability to shows you if in reality goes only to 20hz or below it.

R.

rauliruegas:
"Dear @noble100 : """ All DBA systems will provide accurate, detailed, smooth and natural bass that has an effortless quality to it. """

as can do it non DBA subs system. As you said maybe a different way " to see things " but DBA is not the only or best option. Clearly is for you and other gentlemans but exist other very good alternatives to it."

Hello rauliruegas,

     Yes, it's definitely possible to attain very good bass response using 1 or 2 subs.  As we've discussed previously, this is a bit of a compromise since the 1 or 2 subs need to be precisely positioned in the room to optimize the bass response perceived at a single dedicated listening position.
      This specific sub positioning process for 1 or 2 subs restricts good bass response to the immediate vicinity of the dedicated listening seat and, by necessity, results in much poorer bass response at many other areas of the room.  However, some individuals require good bass response at more than just a single listening position and a 4-sub DBA system is an excellent method to achieve good bass response not only at the dedicated listening seat but also throughout the entire room.

rauliruegas: "Normally the owners of planar type speakers are " against " to run the main speakers as a " satellite " one that is the " right " way to go ( for me. ) because that high-pass filter makes a paramount difference."

     I completely agree with you that one of the major benefits of adding subs, and running the main speakers as satellites, is that it frees the main speakers and their amp from reproducing the bass frequencies which results in less speaker distortion and reduces the demands on the amp.
     In my system, I've tried both configurations of running my planar panel mains full-range and with my mains as satellites with their low frequencies filtered out by the sub amp supplied with the Audio Kinesis Debra DBA system,  This amp has a L/R high pass outputs for sending frequencies above the bass crossover setting to the main speakers amps.
     I thought my system sounded best with the main speakers running full-range. The mid-range and treble range sounded very similar to me with both configurations but I did notice the bass range sounded more detailed and more dynamic with my mains running full-range.  
     I do have some thoughts about why I didn't discern improvements in the mid-range/treble range using the 'satellite method' as expected and as you have in your system.  I'm uncertain of the quality level of the high pass filtering being done in the sub amp.  But since I was unable to discern any differences in the midrange/treble response range between full-range and the satellite methods, I can only conclude that the filtering quality level is not an issue.  
     Also, any sonic gains expected from the reduction on bass frequency amplification demands on the main speakers amps may not have been realized since these mono-block amps are not lacking in power ( 1,200 w into the speakers 4 ohm load).  Another possibility is the Magnepan 2.7QR main speakers I use as mains.  These are 3-way planar panels that have rather large bass sections which provide very high quality bass on their own but that lack deep bass impact.  Perhaps the improved bass response I noticed with running the mains full range is a result of the very high quality and articulate bass of my mains combined with the increased impact and dynamics provided by the AK Debra DBA system.
      I think both our systems are just practical proof that there's several options available for achieving high quality bass response using subs.

Tim

Dear @noble100 : """ All DBA systems will provide accurate, detailed, smooth and natural bass that has an effortless quality to it. """

as can do it non DBA subs system.

This statement is false. If you encounter a standing wave, it often cannot be fixed with only 2 subs. And it can't be fixed with room correction or room treatment.

Now if you **don't** encounter a standing wave then its all good. But in many rooms a standing wave is highly likely- unless the room is irregular in some way. But any rectangular room will have a standing wave which will be a different locations throughout the room depending on the frequency. In such cases while that bass might be good at the listening chair for certain pieces of music, it may not for others. This is a simple fact of physics.

With a distributed bass array this problem is solved.

Dear @noble100  : Yes, with two true self powered subs for one seat position. We don't need more for that target. The Harman white papers confirm it.

I think that even that we agree in some bass management subjects the reality is that we can't agree and not because " we can't " as is but because looking your streamlinen system your targets and mines are totally different.

I don't use my system for HT and two channels listening MUSIC. My system was and is developed exclusively for listen two channels MUSIC, nothing more. Music coming from digital and analog alternatives.

As I told you my main target is to stay " nearer/truer " to the recording and to achieve that target I need a very high resolution room/system that means very high quality performance of any single link in the overall audio system chain with true accuracy and the lowest any kind of distortions I can achieve.
Obviously that to achieve all these we have to take care for the minimum details where in HT no body cares and even in two channels system some audiophiles not cares either. 

I gave that little explanation due that you said that using the high-pass filter you was not aware of differences in the quality level performance in the mid/high frequency ranges in your system.
After looking your system I understand now why you been not aware about: your system has not the resolution need it for even that very wide frequency bass range in the Magnepans.

As a fact you are not trying to put all kind of distortions at its minimum you can and that's why you gave me an answer that THD in the quasi-subs you own was not so important when in reality is way important with true self powered subs in a only two channels system. Everything is important and with high priorities in a two channels room/system when we want to stay not so far aways of live MUSIC as normally we are. 
Mi reference to achieve my target is live MUSIC seated at nearfield position ( 2-3m. ) that's where the  recording microphones are positioned.

For me is really important and was one of the reasons I choosed my servo controled Velodyne's that check every second 16K times the woofer excursions to mantain at lower than 0.5%  the THD. Other than Velodyne I don't know other true subs where the manufacturer gives the THD in its products.
I think I already mentioned that the JL very well regarded subs measured through Stereophile review around 6% on THD other subs reknowed subs are worst that that and certainly far away from that Velodyne figure.

I totally understand your fascination for your 4 quasi-subs bass array because for that price is almost imposible to achieve what you like in your system.
The manufacturer design must had to make " serious " compromises to stay at that so low price for the complete bass 4 array.

Anyway, at the end you have what you and me were looking for and if both of us achieved our targets then this is the more important fact.


Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

@atmasphere --

This statement is false. If you encounter a standing wave, it often cannot be fixed with only 2 subs. And it can't be fixed with room correction or room treatment.

Now if you **don't** encounter a standing wave then its all good. But in many rooms a standing wave is highly likely- unless the room is irregular in some way. But any rectangular room will have a standing wave which will be a different locations throughout the room depending on the frequency. In such cases while that bass might be good at the listening chair for certain pieces of music, it may not for others. This is a simple fact of physics.

With a distributed bass array this problem is solved. 

There's nothing categorically false with poster @rauliruegas statement; you CAN have bass that is accurate, detailed, smooth, natural and effortless with two subs, end of story. Both room correction and -treatment can do wonders here, I find, and can (and should) be used sparingly for a successful outcome. Honestly it's becoming trite hearing the constant babbling about what a pair of subs can't, and the double count can. We know by now - 4 subs can be a hoot, and they ease up on the need for PEQ, definitely not trivial. Moreover, all things being equal a double-up in sub count gives a theoretical 6dB's more headroom, and I can certainly vouch for the importance of that. 

You could however take a pair (or more) of bigger, more sensitive subs placed symmetrically to the main speakers, horn load them even, and have a different kind of awesome with other advantages. I know, size is banned in audiophilia, but the simply fact of physics, to use your own words, also has size as a main priority that numbers can't alleviate. Big subs in high numbers, however..

And what's the issue and argument made with smooth bass coverage over a wider listening (position) window? One sub is a narrow sweet-spot, two is wider and so forth, and while a single sub may boarder on the head-in-a-vise sweet-spot, two is definitely good for a pair of listeners to have decent coverage. I don't know about you guys or ladies, but mostly I tend to listen to my setup by myself (and if not I give the other listener the sweet-spot, usually placing myself on a chair behind and to the side of the listening sofa), and I don't need for bass to be swell in every goddamn place in the listening room; the listening position (with room for two, if need be) will do just fine, thanks. Actually this is mostly dictated by the main speakers; I would never listen seriously any other place than smack in the middle between the mains, but that's just me.