Upgrading sub to get a live feel.

thewatcher101:

The room size is 16x30. The speakers are placed on the 16 side, and I sit about 11 feet away from the speakers. The SB are located right under the main, 6" from the wall.

I'm reading this as your main speakers are 6" from the wall??? Can't be right.

Subs right under, or even real close to the mains is another problem. Some might think this is necessary for timing or whatever. Do a little research. Timing is not a factor with low bass.

Instead what you want is exactly the opposite of timing: a lot of randomly spaced sources. Putting subs close to mains is by duplicating the location robbing you of a lot of the improvement you'd otherwise be getting. Move em.

The SB-1000 are set to about 65Hz to blend, zero phase, 60% volume. I’ve always found very clean and articulate bass at this current settings, and anytime I’ve made an adjustment, I’ve dialed it back to these.

Easily the biggest problem or pitfall with subs is trying to hear them working. When done right you don't hear them at all. No one listening to my system will have any idea there are 5 subs. No one will have any idea there are ANY subs! They certainly will have no idea there are two way back off to either side and behind them. 

My first big mistake in setting these up was getting the levels way too high. Its hard because a lot of recordings have no really low bass to speak of. So its real easy to wind up with too high levels because you used the wrong recording.

Test tones and meters aren't much help either. This is because the way us humans hear really low bass changes depending on volume. See Fletcher-Munson curves. Because of all this what I find works best is just relax, listen to a lot of music at whatever volume levels you like, and don't try and get it dialed in too fast. Be patient, make very small tweaks, and don't try and make any one recording sound perfect.

First test just running one additional sub (3), placed on the left side besides my seat, set at 60Hz, played with gain to peak bass, and 60% volume. The biggest difference is an increased amount of headroom, the speakers felt slightly larger.

Yes. "The biggest difference is an increased amount of headroom, the speakers felt slightly larger." Exactly! 

The bass that comes from adding more subs is completely different than the bass that comes from adding a bigger sub. The difference is exactly what you said, the speakers sound "bigger". 

The thing about really low bass, the frequencies are 40, 80 feet or more in wavelength. Because low bass has such a long wavelength the only places you really hear them are in huge auditoriums or concert halls. Walk into any huge space like that you can tell its a huge space even with your eyes closed. Because of the fundamental low bass resonance. You feel it. It tells you you're enveloped in a vast space.

Now with one or two subs, even really good ones, the low bass reflects and cancels and really cannot truly exist. So you never get this feeling of envelopment. With three or more subs though at some point there are enough extra sources to overcome the cancellations and the really low bass is believably there and you do get this sense of envelopment. This is what is making your speakers sound "bigger".

 It blends well in this position, but you can feel the physical bass being directional. That feeling makes you slightly detract from listening.

Not sure what you're doing. The only time I ever was able to localize a sub the crossover was way too high. Set properly all my bass is incredibly, ubelievably precise and localizable. The bass. Not the speakers. 

Now sometimes the bass on the recording just happens to be coming from where there's a sub. This happened a couple times and bugged me until I realized its not the sub, its the recording. Patience.

Second test, quad sub, placed along side seating position against the wall. Similar settings, but with 45% volume, because the wall gives it a boost. I get a nice spacial balance, but I could not get them to blend in this position. At those settings, I got a bit of harshness in the low regions.

Probably this is just too much bass. Every additional sub adds both extension and headroom- and volume. Adding a sub requires turning down the level on all the subs.

16 x 30 is the room size.

I prefer sealed subs, but the Audiokinesis Swarm was designed as ported, with the option to seal the port with a plug. The set up used by the designer has the woofers facing the wall as jtcf mentioned. When I used a Swarm like set up I had woofers facing into the room and towards the wall. Even had one next to the listening seat and anyone who came over for a listen, including a friend who designs and sells speakers, couldn't hear any of the subs. He had to ask where the 4th sub was located and when I told him to look over the side of the arm rest he chuckled when he spotted the sub.

In my set up now the two front woofers face each other along the front wall, the other two woofers are next to the speakers and face out into the room per a method recommended by mijostyn who has posted on this thread and other sub threads. Both methods work well for me, but given the type of speakers (line array) I am using now the newer method has resulted in increased bass response and more 3D imaging. If I go back to point source speakers I will go back to an asymmetrical arrangement.

They are 6 inches away from the wall, and I'll turn everything down and see how it goes. 

When the SB were originally set up they added additional headroom to the speakers, without being heard were my standards. 

This has been a great thread,  Not too long ago I added a second REL T5 to my Omega Super Alnico Monitors, and things have been sounding really great (16 x 26 room with 8 ft ceiling and open on two sides).  Since reading about the Swarm package and various threads about setting up a dba, I’ve been interested in adding a third subwoofer next, and eventually a 4th.  The question I have is this:  would I get better better bass improvement adding a 3rd T5, which has a single sealed 8-inch driver, or try to get a larger (10 or 12 inch) sub for the third sub? The current subs are run in stereo.  As the new sub would be run off both channels, would I need to reconfigure the others to also run off both channels, or should keep them in stereo.

Hello ihor,

     I would suggest running all three subs in mono and adding a larger 10 or 12 inch sub for your third sub would be the best choices.  
     There are virtually no current or past music recordings in any format (vinyl, cd or hi-rez files) that contain stereo deep bass, all of the bass below about 80-100 Hz is summed to mono on the recordings since humans are unable to localize (tell exactly where the bass is coming from) on bass tones below about 80-100 Hz.
     Even though all three subs are outputting mono bass, you'll perceive the bass as a form of stereo bass, with the sound seeming to come from the proper bass instruments within the soundstage illusion ( for example, the drums are located in the center rear of the soundstage and the upright acoustic bass is located in front of the drums and off to the left.). 

      This is because, even though the fundamental deep bass tones below about 80-100 Hz coming from the subs will not be able to be localized, the related bass harmonics or overtones of the fundamental bass tones coming from the main speakers are able to be localized (since they extend above the 80-100 Hz limit).  Our brains are able to associate the higher frequency bass harmonics/overtones with the much lower frequency bass fundamental tones and thereby determine where the much deeper fundamental bass tones are originating from. This process is one of the principles of he science of psychoacoustics (how our brains process sounds and form perceptions).
      Having a larger 10 or 12 inch sub as the third sub also relies on psychoacoustics and will give the perception that the overall in-room deep bass response has been extended a bit deeper.  
     Proper positioning within your room and the proper setting of the volume, crossover frequency and phase control of each sub are very important for optimizing bass output in your room and integration with your main speakers.

Tim