My experience adding subwoofers to 2 channel

Hello mijostyn,

    Thanks for the clarifications on your system. I know 'ESL' is usually an acronym for electrostatic loudspeaker but mistakenly thought the Acoustat 2 + 2 were planar-magnetic speakers. I now understand they're ESLs with the '2 + 2' designating there are two 94" tall panels utilized for each channel, meaning they're technically not a pair of speakers but a quartet of speakers. My mistake.
     Ever since I bought my 2.7QRs used about 2001 I've been experimenting with single and dual subs in an attempt to incorporate good bass response and impact in the 20-35 Hz range I knew they were lacking.  After a lot of research and some luck, this led to my learning of the 4-sub distributed bass array (DBA) concept and buying the Audio Kinesis Debra 4-sub DBA system on a trial basis about 4 yrs ago.        
      My current thinking is that this DBA system has provided such accurate, detailed, smooth, natural, dynamic and extended bass down to being flat at 20 Hz while also seamlessly integrating with the quality and speed of my planar speakers in my room, that I honestly feel very fortunate to have this high a level of bass quality in my system.
      I realize, however, that a linear bass array sub configuration could provide even better bass performance in my system and room than my distributed bass array.  
      I'm hesitant to find out, though, for several reasons. I have a much better comfort level with the distributed array concept due to a better understanding of the physics and psycho acoustics involved than I do with the linear array concept, the distributed array is already completely hooked up and working extremely well and my wife and I are also very pleased that the 4 subs in my room are currently so physically inconspicuous and well integrated into our combination living, music and ht room.  In addition, it would likely take a large room rearrangement just to give the linear bass array a try and there's no guarantee I would prefer it either.
     I wanted to respond to your questions and suggestions from your last post, too.  My listening chair is backed up to and centered along my room's 16' rear wall.  But I move it about 3 feet out into the room for serious and prolonged listening sessions for better soundstage imaging. My panels are always a minimum of 3 feet and sometimes more away from the pair of subs behind them.  Both sub 10" drivers are also facing the front wall and not directly into the back of these panels.  I notice no detrimental effect in any frequency range from this positioning.
     You also stated: "You have two subs back there with you and you hear those fractionally before you hear the ones on the front wall. This will smear transients. You want to hear all your subs at exactly the same time."  
     It's my understanding that the time-domain on frequencies under 100 Hz are not as critical as some believe.  I also read an article on an experiment proving we don't even detect deep bass sounds until the entire frequency soundwave cycle exists in the room.  The experiment consisted of subjects wearing headphones.  A series of computer generated  partial and full cycle deep bass tone soundwaves were played and the subjects only were able to detect the bass tones in which the full cycle was played and no sound at all when the partial cycles were played.  As you know, it takes some time and distance for a full 56 foot long 20 Hz soundwave to develop in a 23 x16 foot room.

Tim 
      

I have used a tri-amped electronically crossed three way line array system that I built myself.  This worked seamlessly.  The 12 inch woofers worked well as subs essentially running 32- 250 hz.

I am currently building a new system to go downstairs(sine my wife commandeered the other one for watching movies upstairs).

This one will be a Quad amped electronically crossed  line array: per side:  15 ribbon tweeters, 25- 2 inch midranges, one 8 inch mid woofer, and one 12 inch sub woofer.  

Electronic crossovers(digital or analog) are the key to making this work, IMO.

I recently purchased some transmission line (like) ported towers and was unable to successfully integrate my single sub- so I sold it.  
I have had no problems in the past with typical ported monitor speakers- and am quite good at integration using RTA, phase control for time delay, etc.  
I could not get the bass to sound good- often hard sounding despite my efforts.

I had no peaks in the response either so EQ will not help.  

I'm guessing that transmission line ports are somehow more difficult to integrate.
I miss the impact my sub provided and any advise would be appreciated.  

zarathu,
     
    I wasn't implying speaker and sub line array configurations don't work well, I know they do.  I was just stating these arrays are best for a dedicated room or stage, using them in a living room requires serious rearrangement of the décor.

Tim    

The idea mijostyn has (and others, he is far from alone in this) of bass timing being smeared is of course based on the false assumption that human hearing responds to all frequencies equally.

That this is false is proven by a simple experiment in which subjects wearing headphones are played test tones of short duration. This test demonstrates conclusively that less than one full wavelength of low frequency bass is not heard AT ALL. Say again, human hearing does not even register very low bass less than one full wave duration.

Understand what this means? A single 20 Hz wave lasts 0.05 seconds. Anything 20 Hz lasting less than 0.05 seconds will not be heard at all. Sound travels roughly one foot per millisecond. Ballpark. So think about it. Bass can travel FIFTY FEET before we are even capable of hearing it.

So I ask, from the point of view of timing- not frequency response, just timing- how in the world is it possibly going to matter where you put the subs? Any normal size room the bass is going to leave the speaker, bounce off half a dozen surfaces, probably more than once, all before you even hear it.

Yes timing is super important - at high frequencies. I take heat on here all the time for saying speaker placement being off as little as 1/8" matters. But that’s high frequencies. Low bass is completely different.

Just one of several deeply ingrained yet totally false concepts hampering our ability to understand the beauty of the distributed bass array.