Why the fascination with subwoofers?

you CAN have bass that is accurate, detailed, smooth, natural and effortless with two subs, end of story.

Sure. That is why I qualified my comment: 

**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.

(emphasis added; ***IF***)
If you *don't* have troubles with a standing wave then one or two subs can give excellent response.

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.

What I really mean was not a LP limitation perse but an analog rig limitation because cartridges just can't track with applomb very low bass grooves.

Telarc 1812 is a good example where I own over 120+ cartridges and only a few can track those cannon shots with clean and pristine true applomb.
Between other things cartridge self abilities is always a limitation and not only at very low bass.

@rauliruegas More depends on the tone arm's ability to track the cartridge than it does on the cartridge itself. Its a good bet that when they cut that track they played it on a very ordinary turntable to make sure it was playable.

Seems to me that because the recording of LP’s during the cutting proccess the bass information must goes in MONO due to the analog/LP limitations the producers/engeneers accustom to never think to make CD recordings taking advantage of the digital alternative that has no limitations about ! ! ? ? ? ? Maybe exist something in those very low bass information that the microphones pick-up that could or can makes useles doing it in Stereo fashion, who knows?

Its not so much the limitations of the format as it costs a lot of money to pay an engineer to work a way around  "out of phase bass". If you spend the time with the recording, you can usually find a way to master it without having to process it. But that takes time and at $500/hour most often bass processing is used. This is a simple circuit that senses when bass is out of phase and makes it mono below about 80Hz for a few milliseconds until the event has passed. This makes mastering LPs less expensive!

But CDs do exist where out of phase bass exists. This can happen because a microphone is out of phase with the rest of the recording when a bass guitar or bass drum is recorded. For this reason, the recording engineer has a phase inversion switch on every channel of his mixer but he may not have thought to use them.


If the recording is done in its entirety with only two mics, out of phase bass will not exist.

@rauliruegas
When I make comments regarding the sound or effectiveness of a thing in audio, if they are subjective in nature I use recordings that I made since I was there at the recording session and know how they are supposed to sound. I had the recordings produced on LP and CD.

It is the nature of this sort of thing that only I know how they are truly supposed to sound as would be the case for anyone who was at those recording sessions. For example if I say the Triplanar arm reproduces bass better than any other tone arm I've heard its because I was there and have the master tapes; other arms simply don't seem to get the bass right.

So my suggestion to you is simple- get some good quality recording gear and make your own recordings so you can make accurate statements about things rather than speculation posed as fact.

^^ I suggest you make a recording with very low bass on it and see. I find that the most useful way to have a true reference.

For a 10" woofer ( as the four subs array posted here. ) is almost imposible to handled frequencies below 20hz at over 100dbs ( SPL. ) and with low THD kind of distortion.

This statement is false.

The Swarm takes advantage of room boundary effects as explained on the audiokinesis.com website.

Can someone define for me what "tight" bass is.

An artifact of sound reproduction. It does not seem to occur in real life. Punch but no detail, in a nutshell.

To address Raul's attacks against me: I don't sell speakers of any sort. I recently moved, and now have a standing wave in my new listening room. I've seen how effective the Swarm addresses this so I know they will work in my situation. I only need two, as my speakers go down to 20Hz no worries.

Do you have to play a mono (i.e., summed) signal from all the subs or would there be value to trying the front subs in stereo and the rear subs or one rear sub in mono to better deal with standing waves?

I'd put the side subs in mono. That's the plan in my system since my speakers already go solid to 20Hz.

Ralph: if I'm taking measurements and measure a deep valley within the subwoofer frequency, would that be pointing to a standing wave?

That would be my first suspicion!
 

For example, the kick drum dead center and the upright bass a few feet forward and a few feet left of the kick drum.
     I can only explain this by assuming that the higher harmonics or overtones of the deep bass fundamental notes's frequencies extend beyond 80 Hz and are being reproduced by my main speakers, giving my brain the clues it requires to associate the higher directional harmonic frequencies with the much deeper and non-directional fundamental frequencies reproduced by my bass system and determine the specific locations of the bass instruments.

Yup- that's exactly how it works.

Ok, so you don't use swarm, but I take you are replicating the concept: distributed bass array playing a mono signal. Is the goal to minimize SPL variations at different seating locations? Or to optimize at the prime seat?
How did you determined you needed to break down a standing wave?

The goal is uniform bass response in a greater portion of the room including the listening positions. I've done lots of setups over the decades as I've been doing audio shows since the late 1980s; so the answer to your third question is 'experience'. Standing waves are a common problem in a lot of rooms. One time we used an Accuphase room correction device but quickly learned that it can't do anything about a standing wave. If one is present, you can put as much power into it as you like and at the null point the bass still won't be right.

So the elegant approach is to use a distributed bass array system like the Swarm, which is the best example out there.

I have a pair of 12" sealed subs playing mono and been wondering about adding one or two more with the goal of flattening at the main seat. Would love to know your take on this.

I'd give it a shot. I don't use the Swarm but if I had it to do over that's the route I'd likely take. Duke is working on a sub system for me though- one that is integrated into a coffee table. It will be used to break up the standing wave in my room.

Many do try to do just that. Look around however, it quickly becomes very obvious the hardest most expensive thing you can find is two quality speakers with true 20 Hz bass. They essentially do not exist. Turns out (read on) that for reasons of physics they cannot exist. Which is why they don’t.

@millercarbon
This statement appears to be false.


My speakers at home are made by Classic Audio Loudspeakers. They are the model T-3.3.


They have a pair of 15" woofers. One of the them is the TAD 1602, which has a free air resonance of 21 Hz. Are you really trying to say that a speaker like that in a properly tuned bass reflex cabinet (my speakers are the size of refrigerators) can't go to 20Hz?? They seem to have plenty of undistorted output at 20Hz in my room.

One problem with full range systems is that standing waves often exist in the listening room. This can mean bass in most areas except the listening chair. The solution isn't room treatment, its placement of several subs in such a way as to break up the standing wave.

The Audiokinesis Swarm is thus one of the best sub systems made.

My speakers (Classic Audio Loudspeakers T-3) go down to 20Hz flat no worries. But I still have to employ subs to break up the standing wave else the bottom octave is not audible at the listening position although it certainly is everywhere else in the house.