Are big subwoofers viable for 2 channel music?

Lusima31 wrote: "I found the same with my 4 AK subs, without the port plugs they sound very good so the sealed vs vented sub dilemma I have a feeling it depends on other things, maybe the dimensions (length and diameter) of the port in proportion to the enclosure? Not saying sealed is not good, just that I assumed for music sealed was always better and Duke prove otherwise."

Thank you Luis!

Arguably what matters most is the in-room frequency response. The ear is far more sensitive to frequency response than to time-domain response in the bass region, so the superior group delay behavior of a sealed sub is not a significant factor in sealed vs ported. (This is somewhat counter-intuitive, and is among the things I learned from Earl Geddes.)

Imo the correct "target response" for a subwoofer would take into account the effects of boundary reinforcement. "Typical" room gain from boundary reinforcement is about +3 dB per octave south of 100 Hz, according to a couple of different sources, but obviously it will vary with the specific acoustic conditions.

So let me try to explain what I believe to be the primary reason why sealed subs tend to sound better than vented subs: In general a sealed sub starts rolling off higher than a vented sub, but its rolloff is more gentle; whereas a vented sub is "flat" down to a lower frequency, then rolls off rapidly. Factor in room gain, and vented subs tend to have exaggerated low end above their inherent rapid rolloff, which tends to sound "boomy" and/or "slow"; on the other hand, room gain synergizes pretty well with the gentle rolloff of sealed subs. (This is all without factoring in EQ.)

The target response for my Swarm units in ported mode is the approximate inverse of room gain: They gently roll off at about 3 dB per octave from 80 Hz down to about 20 Hz, and then the rolloff accelerates rapidly below 20 Hz. Not saying this is the only valid approach, but it seems to work pretty well.

Luis again: "Just that Duke of AudioKinesis if I’m not mistaken was the 1st "commercially" to approach the array, the concept and theory comes from Geddes I believe?"

That’s correct. When Earl described his subwoofer concept to me, I immediately asked him if I could license it. He said no, that I could just use it. So the Swarm uses Earl’s ideas with his permission... but anyone else can use them as well, no permission required. He has trade secrets which he keeps to himself, but the distributed multi-sub concept is not among them.

Duke

Tyray asked: "Can a customer use their own passive subwoofers of choice?"

You can totally use your subs of choice, active or passive. Here is the amplifier that I use to drive my passive subs, note that it has a single band of EQ and a switchable 25 Hz "bass boost" circuit, which may come in handy with sealed subs:

https://www.parts-express.com/dayton-audio-sa1000-subwoofer-amplifier-rack-mountable--300-811

Tyray: "Or do I have to use AudioKinesis designed passive speakers for best results?"

I think the subs I designed work well for this application, but they are NOT required for good results. I don’t like to make claims like "best results" because in this hobby there is always something better... I’ll only claim "best I know how to make at my price point given where I think the goal posts are."

Tyray: "As I’m trying to understand if you would need to ’customize’ your swarm peripherals, amps, speaker wire, crossovers and any other hardware to work with the subs a customer may propose."

I don’t really "do" custom Swarm systems wherein I don’t at least supply the passive subs, but it’s not rocket surgery. Briefly...

Spread your subs asymmetrically around the room, perhaps with one (but no more than one) in a corner, and bonus points if you can raise at least one sub up off the floor such that it is closer to the ceiling than to the floor.

(If you prefer, you can also use a symmetrical configuration - see Todd Welti’s "Subwoofers: Optimum Numbers and Locations" on Harman’s website.)

Any subs which are fairly far from the main speakers, you want their top ends to be rolled off fairly steeply no higher than 80 Hz, so they don’t betray their locations by passing audible upper bass/lower midrange.

I usually find that reversing the polarity of the sub farthest from the main speakers tends to improve the in-room smoothness, but in a very large or open-floorplan room the result may be deficient in the bottom octave.

If you don’t have test equipment, when setting the controls on your subwoofer amp(s) by ear, the sequence is: First set the level, then the frequency, then the phase. Cycle back through this sequence several times to fine-tune. Credit to master acoustician Jeff Hedback for teaching me what the proper sequence is.

Duke

Tyray wrote:  "Duke, I have been to the Swarm website this weekend but did not see the Azel's? Could you give me a link to the Azel's and any other of your products I may have missed please. Thanks!" 

My website is being revised, but Jim Romeyn's site has all of my current designs.  Jim is my partner in crime... for example the Space Generators that Luis mentioned were his invention: 

https://jamesromeyn.com/ 

Duke

To smodtactical,

Imo the sheer size of your large listening space bodes well for bass reproduction. Arguably what the Swarm does in a smaller room is, approximate the in-room response that we’d get with fewer subs in a much larger room. I do think your square footprint makes asymmetrical sub placement worth a shot, and you may well get very good results with only two big subs. As an alternative to asymmetrical, particularly if your two subs have phase controls, I suggest center of the left and right walls, and then dial in 90 degrees of phase difference between the two subs.

Despite the fact that I use four relatively "small" subs, I do not subscribe to the school of thought that says small woofers are "faster". What we perceive as "speed" in the bass region is directly related to the in-room frequency response curve. To the extent that small woofers tend to have less low bass they may be perceived as "faster", but that’s not a direct result of the cone diameter in and of itself.

I do not have first-hand experience with very many of my competitor’s subs, but ime the Rhythmiks are very good. A pair of big Rhythmiks in your big room would be hard to beat.

Duke