Are big subwoofers viable for 2 channel music?

luisma31:
"It is funny you said "they sound" the beauty of bass in my system is I forget about the subs, I don’t tweak them, they are part of the room’s furniture, I totally forget these exist, I don’t "hear them". The only time I realize they are there is when I play rock and my wife starts screaming because candles and ornaments she put on top of the subs start falling off, otherwise to me they don’t sound."


Hello luisma31,

You’re mixing up 2 different factors when properly incorporating subs into an audio system: seamless integration of the subs and the sound quality of the subs.
Yes, seamless integration of the subs requires they only become active when the source material demands the reproduction of bass frequencies at or below the selected cutoff frequency. This requires a good knowledge of one’s main speakers’ bass extension performance and a bit of experimentation with the sub’s volume and cutoff frequency controls to augment the bass optimally.
I’ve found that a good guideline, for good integration between subs and the main speakers, is to try and set the volume and crossover frequency as low as possible with the bass still sounding powerful, smooth, fast, detailed, dynamic and natural when activated. I’ve also found that a pair of subs allows the bass to integrate with the main speakers about twice as well as a single sub. Four subs, positioned in a distributed bass array configuration, will integrate about twice as well as a pair of subs and integrate seamlessly with virtually any pair of main speakers and in any room. Eight subs, positioned in a distributed bass configuration in a room, are solid grounds for divorce in most states.
However, seamless integration between subs and main speakers is only one factor in achieving good in-room bass performance, the other is the sound quality performance of the subs. Just like main speakers, the sound quality of subs varies. Fortunately though, there are numerous low distortion, good quality subs that reproduce high sound quality bass sound waves.
To further complicate matters and just like the woofers on main speakers with deep bass extension, it’s not sufficient that subs launch high quality bass sound waves into the room. These high quality bass sound waves must arrive at the listening seat in the same condition for the bass to be perceived as high quality.
In general, the bass is the hardest part of the audible audio spectrum to get right in most systems and rooms. This is primarily due to the fact that bass sound waves are very long and omnidirectional which behave much differently than the much shorter and directional midrange and treble sound waves in typical, domestic-size rooms.
I’ll spare all the details right now, but this means that the woofer positions within the room launching bass soundwaves, whether within main speakers or subs, must be precisely positioned in the room to guarantee these sound waves arrive at the listening position unaltered so that the bass is perceived as high quality, with no bass peaks, dips or nulls perceived.
Given these facts, it’s easy to realize that achieving high sound quality bass at one’s listening position is much more difficult using main speakers with deep bass extension, that are normally positioned within the room to optimize midrange, treble and imaging performance and not bass performance, than using separate, independently positioned subs are capable of achieving. Also, bass integration and sound quality are both improved as more independently positioned subs are added to the room, with the majority of bass sound quality benefits attained through the presence of 4 subs.
The above is why I decided to treat my system as 2 systems, a bass system that I optimize by using a 4-sub Audio Kinesis distributed bass array system and a midrange/treble/imaging system that I optimize by using a pair of Magnepan 3.7i main speakers. Overall, this results in a high quality and full-range audio system that I really enjoy.


Tim

Thank you Tim for adding details

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

I found the same with my 4 AK subs

I had PSA before, very powerful subs

for two channel systems definitely a swarm or array provides what you are looking for, you can select from existing of the shelf subs or go custom, a big part of it is how are you planning to integrate the 4 (minimal qty) subs,

I went custom and currently running 4 passive subs and could not be happier

@luisma31,

Would you mind describing your setup and the AudioKinesis gear used?

Duke,

I’m very close to becoming a customer in the future but can a customer use their own passive subwoofers of choice? Or do I have to use AudioKinesis designed passive speakers for best results? 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. Or if you can or cannot do such a thing? I'm asking these questions with complete respect and sincerity of what you do and have accomplished and am just curious?

Tim, it might surprise you to hear that the system with the best bass I've ever heard consisted of two subwoofers and that they were crossed over at 120. I was quite surprised at the crossover point, but there was no denying what I (and a number of other pretty serious enthusiasts heard).

There's more than one way to skin a cat.