Dual vs single sub

phusis:
" Why try and make a case with a limited number of CD’s (what genre, age of mix, etc.?) to conclude that there’s virtually no recorded true-stereo bass?"

Hello phusis,
     I don't believe it was millercarbon who tried to make a case that there's virtually no recorded true-stereo bass content.    I think it was Audiokinesis/Duke who mentioned the rarity of recordings with stereo bass earlier on this thread.
    I know that his AK Swarm and Debra distributed bass array systems, with the addition of a 2nd Dayton sub amp, is capable of being positioned in a manner that would successfully reproduce stereo bass.
    If I recall correctly, however, Duke stated he wasn't aware of any content containing true-stereo bass and asked if anyone else knew of any content recorded with true-stereo bass.  I'm not aware of any and apparently no one else reading this thread is, either.  
     You seemed a bit offended when you mistakenly thought millercarbon had tried to make a case that there was just a 'limited' number of cds containing true-stereo bass when there appears to be none.      
     Are you aware of any recorded content with true-stereo bass?
     Just to be clear, I know it's very possible to attain very good bass response at a single sweet spot location using 2 good subs.  My point is that it will be very good mono bass, not true-stereo bass.

Tim

@audiokinesis --

The distributed multi-sub approach has nothing to do with whether or not the mains are highpassed. Those are two separate decisions. I’m probably the one who caused the confusion because I’m a distributed multi-sub advocate but not an advocate of automatically high-passing the mains in every situation. I think it depends on the specifics.

I know, Duke re: multi-sub approach and high-passing mains, but I brought this into the mix, so to speak, because it's my impression the general gist with multi-sub use is to cross fairly low to the mains (i.e.: without high-passing them), not least taking into account the directionality at higher frequencies and how this could be seen as an issue with subs scattered throughout the room around the listener. 

I did refer to high-passing the mains as a "potential benefit," which is also a way of saying that I side with your view on how it "depends on the specifics." 

The distributed multi-sub approach apparently works well in many situations, but is not the only approach that works well, and in some situations it would not be the approach I'd choose. It depends on the specific situation. 

I believe this has always come across rather consistently from your writings, certainly implicitly, contrary to other advocates here of the 4-sub approach who seem quite adamant of it being the only true quality solution, so much indeed that considering otherwise is "not getting it." Again, I've heard great 4-sub setups, no contention here, but I believe a symmetrically placed 2-sub setup can make wonders as well.

phusis you are right. A point source system can be wonderful with two subs set up correctly. A line source requires four subs in most rooms (wall up to 16 feet). Now I am going to make some people mad. Distributing the subs through out the room makes no sense. Once the subs are more than 5 to 10 feet apart depending on cross over point they act as two completely separate drivers with 2 separate interference patterns in the room. At 10 feet you would have to cross over below 40 Hz. Systems benefit greatly from high pass filters. It relieves the main amp from having to produce low frequency transients which require a lot of power. They also eliminate Doppler distortion from the satellite low frequency drivers cleaning them up. You get more improvement the higher you cross (but not too high). But with distributed woofers you can't cross above 80 Hz or you screw up the image (some would say lower). If you want the most benefit from multiple woofers, the lowest distortion from your satellites,
A great image and absolute thundering bass with the lowest room interference, set up the four woofers along one wall right up against it symmetrically in regards to the satellites right and left channels. The far woofers should go right in the corners, the near just to the inside of the satellites. Cross over between 100 and 130 Hz 12 to 24 db/octave and use high pass filters. Don't believe me. Try it for yourself if you have the equipment. I do have the equipment and I have been using multiple subs since 1979 and have set them up in every configuration you can think of using every conceivable cross over. Experience is always the best teacher. Aside from listening to music this is where the fun is in this hobby, playing around with your system. Once you have the equipment you can play around with the configuration room constraints allowing. As long as you are a good listener you are in business. Back to Stravinsky! 

Hello hifidream,

    Congratulations on creating your own custom distributed bass array system for your Magnepan20.1 speakers. I know the 20.1s have very good bass performance in stock form with 2 large planar-magnetic bass panels in each speaker that all output down to 25 Hz. Not full extension to 20 Hz like many good subs but close and very respectable.
    Counting each pair of bass panels as a sub, I would suggest you're actually using a total of 6 subs in your room/system. While 2 aren't outputting bass that's fully extended, they're both outputting the exceptionally fast, articulate and smooth bass provided by planar-magnetic panels down to a deep bass level of 25 Hz.  

      Since we've both experienced the amazing seamless integration with even fast planar-magnetic panel speakers (whether mid-level models like mine or top of the line models like yours) and the high quality bass produced using 4-sub dba systems, I think it's safe to assume you'd agree that the dba concept works exceptionally well.

Tim