Cardioid Subwoofers, Open Baffle, etc... What Helps with Room Issues?

[stevenswall]

Waveguides and even off axis response help a ton with monitors sounding decent in an untreated room, and getting a phantom center.

Now I want a subwoofer that I hopefully don't have to do a subwoofer crawl for, as I'd like something I can use as a stand for a TV, or maybe two that I can use as a stand for speakers... Don't want to discover that the best place for subwoofers is all over the place.

Two or more typical subwoofers in ideal locations would be better for even bass, but I'd like to see if there is something that isn't typical.

Here are a few things I've found, though the tradeoffs seems to be extreme prices, or "PA" stuff that doesn't go very low, just loud:
-Genelec W371 goes really low and controls the dispersion by using a second woofer in the rear to cancel some of the radiation. $18k, two recommended, used as stands.
-QSC KS212C doesn't go very low looking at the specs, but gets rid of 15dB of rear radiation. $1.6k, much more affordable and I'd likely put it under the TV if it didn't shake too much.
-Fulcrum Acoustic 18" has an F10 of 30hz, and has 10dB of rear output reduction, probably using vents like the Dutch&Dutch 8C since it only has one driver.

Anything I'm missing? Are there open baffle woofers that help with room issues? Maybe some massive thing with four opposing 18" woofers could overcome room issues by being like 4 woofers in slightly different locations?

 

[Blumlein 88]

I'd been wondering the same thing.

https://www.prosoundtraining.com/2010/03/10/do-it-yourself-cardioid-sub/

If you haven't seen this, it is a simple explanation of what makes for a cardioid subwoofer. Basically you need a delay and some filtering. Pretty much how QSC does it. There are some more complicated details out there if you look for them.

Still you'd need at least two of them to make one card sub. So in a small residential environment is that better than just two subs or maybe four smaller subs spaced about? I don't know.

Now you can make a card by combining a open baffle dipolar sub and a sealed omni sub. Those naturally cancel out into a cardioid pattern. However, the baffle I believe will need to be an unwieldy large size.

 

[Kvalsvoll]

In a small room (small - as in acoustically small - means any room in domestic homes) it makes no sense to have subwoofer units with directivity control, though a true dipole will create a different sound pattern compared to the more ordinary omni radiating ones.

This has to do with distances and dimensions inside the room compared to wavelengths. At low frequencies, the boundaries of the room becomes part of the loudspeaker.

Getting reasonably good bass in a small room is a solved problem. It is done by placing multiple subwoofer units close to boundaries/walls, and use of dsp eq to fix resonances. Any room can get reasonable bass, often with only 2 subwoofer units.

 

[Pultzar]

In my experience, it depends on the room, location, and type of sub. I have a weird shaped room and monopole subs work best in certain locations and horrible in others. The same is true for dipole subs. So right now I'm trying both together with good results, but looking forward to what MSO or Dirac bass correction can do.

 

[pierre]

If you have a rectangular room, you can use the room simulator in REW to see where to put the subwoofers. You don’t need to crawl anymore. Dynaudio has a Sub 18S that can (maybe) be put in cardio mode. KS Digital had this Adm sub.

 

[Peas]

Surely, you stumbled across DBA, SBA and also Multisub by Geddes.

Another option are ripoles, e.g. placed under the couch table: https://www.audiosciencereview.com/forum/index.php?threads/diy-ripole-subs.7575/#post-397956

You will still need a DSP with dipole, ripole or cardio designs as they excite the longitudinal mode in full.

 

[stevenswall]

^Currently trying a swarm based system... But it doesn't stay even vertically like my speakers do. Guess they only work on one vertical plan if I'm trying to get most of the room sounding even. (Use case is yoga, video games on the floor, and movies on the couch.)

 

[tifune]

Just curious where you landed, if anywhere? I see that Presonus and ElectroVoice both have some stackable options, but being they're for live sound I'm not certain they're what we're really after. Even if you can get past the appearance of these in your listening room, the extension leaves quite a bit to be desired compared to even a measly 7350 that offers -6dB @ 22Hz. Of course, if you have a use for 125dB+ i guess it's a different story. Also, the cardioid effect is a bit limited. It's not exactly the laser beam you see on a W371.

https://electrovoice.com/media/downloads/cardioid_subwoofer_arrays_settings.pdf

How to Set Up a Subwoofer for Maximum Punch | PreSonus

www.presonus.com

It did get me thinking, though, why can't any off-the-shelf DSP achieve the same with any subs as long as they're identical? For example, 2x SB-1000's with identical settings and a miniDSP manipulating phase & delay. I'm not expecting miracles but it seems reasonable one could get at least same amount of cancellation as what Presonus is offering, with more extension.