Upgrading sub to get a live feel.

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

Tim, thanks for your response.  This makes sense.  Looking forward to pursuing this dba!  The positioning and setting crossovers, phases, and volume will be the ultimate task and key to success.

Hello ihor,

     Cool, it's a bit difficult to put into words and I'm glad you understood.  I can help you with the positioning and proper setting of the volume, crossover frequencies and phase controls when you get your third sub. Just send me a personal message or post again on this thread when you're ready.

Tim

@mcreyn --

phusis,

Tapped horns are awesome, make mine a DTS-10.

They are indeed, but few know of this - certainly outside the Avsforum and similar-ish sites where bass performance is explored rather uninhibitedly. Tapped Horns are bandwidth limited in their upper range (depending on the tune), and one needs to know what he/she is dealing with and the specific context in which they’re to be implemented to make the most of them. Once you do, and accept size is inescapable, it’s obvious bass isn’t just bass - irrespective of the configuration.

The DTS-10 is a beast. I’d give up a few Hz in the bottom end and go with the TH-50 instead (or even a few Hz more to favor Josh Ricci’s B&C 21"-fitted Othorn), but that’s just me ;) My own MicroWrecker’s are very much influenced by the TH-50, with a tune in the same ballpark as well.

I am not a big fan of 6th order enclosures, they lean towards a narrow frequency range and have to built perfectly to specification or it all falls apart. For high output with limited space, 6th order enclosures have a place. There is a reason the SPL car guys use them. I did build and use a 4th order bandbass for a car for several years, but that was when power was limited and it gave good output for the space.

Sorry I wasn’t clear on this, but I had Josh Ricci’s Skhorn and Skrams in mind when I made mentioned of the 6th order bandpass iterations, rather than making a generalized statement. Otherwise I take it you are absolutely right in your observations, apart from pointing out that Ricci’s designs here are actually less bandwidth limited in the upper end compared to tapped horns.

I wouldn’t mention any of the sub designs brought about here (in pairs, preferably, with more of them being a bonus if space permits) if I didn’t believe they’d be potentially excellent combos with the OP’s future main speaker consideration. Properly implemented he’d have at least 25Hz honest extension and a totally effortless, smooth and "live" bass with proper energy in the midbass. 

I’d stress that this is about acquiring the best possible bass response and integration, and that a vital part of this is attained via ample headroom (from great sub designs) to sport extremely low THD, even at "full chat." Headroom is hugely important; to have the SPL capacity way beyond what one needs, as it both relaxes and empowers the presentation.