Do you use a Subwoofer when listening to stereo?

I don’t get multiple subs.

waves of low frequencies are very large so the spread all over quite well.  A nice 12 inch drive does not seem to need any help in a room that’s say 15x20.  Smaller subs I guess might be spotty and maybe more than one might make sense.

Further, does it really matter where the sub is positionEd?  If I blindfolded someone and said find the sub, could you find it?

Hello emergingsoul.
Here are some answers to your statements and questions from your last post on this thread:

emergingsoul:" I don’t get multiple subs.
waves of low frequencies are very large so the spread all over quite well. A nice 12 inch drive does not seem to need any help in a room that’s say 15x20. Smaller subs I guess might be spotty and maybe more than one might make sense."

noble100: Low frequency sound waves are not actually very large but they are very long. A deep bass 20 Hz sound wave is about 56’ long.
     It’s also not true that the 12" woofer drivers in your pair of B&W floorstanding tower speakers don’t need any help in your 15’x20’ room. You are correct, however, that the bass sound waves launched by the woofers in your speakers do radiate outward in all directions. Once your pair of tower speakers launch their bass sound waves into the room in an omnidirectional pattern, however, the physical dynamics involved do become a bit more complex.
     Once these long bass sound waves are launched into your room, they proceed in an outward direction until they encounter a room boundary (floor, ceiling or wall) and are reflected in a different direction. These reflected bass sound waves then proceed in a redirected path until they encounter another room boundary, run out of energy and decay or collide with another bass sound wave.
     Whenever these reflected bass sound waves collide into each other, they create what is called a ’room bass mode’ at the specific room point of the sound waves collision. When these bass room modes are detected by our ears, they are processed by our brains and a perception is created of hearing one of three possibilities, depending on the angle and direction of the collision, at this specific room location: a ’bass peak’ that’s perceived as a bass overemphasis, a ’bass dip’ that’s perceived as a bass attenuation or a ’bass null’ that’s perceived as an absence of bass.
     At this point, it’s necessary to introduce another factor into my explanation of your room and system bass dynamics realities, the use of fixed position bass sources. Since you probably position your main speakers in your room and in relation to your designated listening position like most of us do, to optimize the midrange, treble and stereo imaging performance, this creates an impediment to optimizing bass performance at the LP. This is because there are only 2 bass sources (your pair of B&W floorstanding tower speakers) launching bass sound waves into your room and they’re permanently affixed in their floorstanding tower speaker cabinets.
     This means these 2 bass sources are unable to be independently positioned in your room, and in relation to your listening position, to optimize bass performance at your LP. The main issue with having fixed position bass sources in your room, such as your pair of floorstanding tower speakers, is that you’re unable to ensure there are no room bass modes existing at your designated listening position. This means you could have a significant bass room mode at your LP, which you would perceive as a significant bass peak, dip or null, and the only remedy is to independently position and configure 1 or more bass sources/subs in your room.
     It’s also important to understand the well understood psychoacoustic principles that come into effect when multiple bass sources/subs are utilized in a room. For example, the 3-4 sub distributed bass array (DBA) concept that provides near state of the art bass performance to virtually any domestic sized room and seamlessly integrates with any pair and type of main speakers, creates the perception of being in a larger space even in small rooms and is the basic concept behind the award winning Audio Kinesis Swarm 4-sub DBA complete kit system linked to here:

https://www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/

     This 3-4 sub DBA concept, whether a custom system or an AK complete kit system, is based on a well understood, but somewhat counter intuitive, psychoacoustic principle that relies on increasing, rather than decreasing, the number of bass modes existing in the room. Adding bass sources/subs to a room increases the number of bass sound waves launched into the room, which in turn and reliably increases the number of bass sound wave collisions in the room which results in an increase in the number of bass modes present in the room.
     Fortunately, this is where our brains and psychoacoustics take over, make sense of it all and ’do the magic that they do’. Psycho-acousticians (yes, that’s what they’re actually referred to as.) have discovered that when our brains are confronted with a sound environment containing an excess of bass room modes, they process and make sense of this chaos by summing and averaging these numerous bass modes by frequency. As a result, our brains create a perception of the bass in the room as being powerful, smooth, fast, detailed, tonally accurate, dynamic and seamlessly integrated with the main speakers.
     I realize this all sounds too good to be true but I can attest to the fact that my AK Debra 4-sub complete kit DBA definitely provides these spectacular results in my combo 2-ch music and 5.4 surround sound home theater system and 23’16’ room for the past 5+ years.
     Attempting to spread the word on the DBA’s incredible effectiveness has, admittedly, been somewhat frustrating since I understand all my words may convince noone but, even a brief audition of a properly positioned and configured DBA, would likely convince virtually anyone.
     If you feel curious and adventuress, emergingsoul, I suggest you could begin to experiment, and experience the benefits of the DBA concept, by creating a basic 3-sub DBA in your room. You could consider and utilize your existing pair of main speakers as 2 fixed position subs, obtain a good quality new or used sub as sub #3 and optimally position it in your room using the ’sub crawl method’. You can google the term for details.

emergingsoul: " Further, does it really matter where the sub is positioned? If I blindfolded someone and said find the sub, could you find it?"

noble100: Most humans cannot localize (determine specifically where a sound is coming from) sound tones that have frequencies below about 80 Hz. So, as long as the sub’s low frequency crossover filter control is set at about 80 Hz or lower, the sub should be able to be positioned anywhere in your room.

I hope this thesis helped you,
Tim

That is a reasonable explanation Tim until you get to the radiation pattern of line sources. Line sources project power (volume) better than point sources. To quality as a line source the speaker either has to be taller than the longest wavelength it is to reproduce or end at two boundaries like the floor and ceiling. People think of ESL being rather polite but if you make one 8 feet tall and put it in an 8 foot room the gloves come right off. The problem for subwoofers is that if you put a point source subwoofer system under a line source speaker it will disappear as you move away from the speaker. Now, if drivers are closer together then 1/2 the shortest wavelength they are to reproduce than they will function acoustically as one driver. This is the principle behind the  D'Appolito array. Four subwoofers running as high as 125 Hz this means they have to be no further than 4 feet apart. But to do 20 Hz the array would have to be longer than 52 feet. Fortunately rooms have walls and we can use them as boundaries so as long as your subwoofer array stretches from wall to wall you are in business. Thus my subwoofer system is functioning as one large linear array subwoofer producing one large wavefront. Remember line sources do not radiate up or down. If you but the subs against the front wall there is no early reflection point off that wall so only the floor and ceiling are comb filtering. On top of this you get all the benefits of a swarm system. Moving to the swarm as is normally used with say an 80 Hz crossover, to function as one driver the the subs would have to be within 8 feet of each other which is actually doable in most rooms. If you kept them all within 8 feet from one to the next what would happen? Tim, why don't you do that experiment and let us know what happens. I have no idea. 

My experience is different but I think I might go about it differently than most. Up at the crossover point I am just listening and I do not want to hear it. The subwoofers should just disappear(remember I use a crossover point of 125 Hz). It has to sound like I am listening to one speaker. As I evaluate lower down I go from listening to feeling. Do I feel that kick drum the way I do at the club. Are those low synthesizer notes shaking me the way they should. Does the room move under low organ pedal. Hearing is one thing feeling is another. Part of the thrill of live music are the visceral sensations you get.
These sensations are missing or greatly attenuated in most home systems.

@mijostyn   You mentioned that your room has not standing waves which is a bit of an achievement so naturally you would not set up your system the same way.


Crossing over the woofers at 125Hz requires that you do what you are doing. Try crossing over so that there's no output at 80Hz and see how much correction you need.


I get similar impact on my speakers at home, which are flat to 20Hz. The problem I run into is a standing wave that causes a loss of bass on certain notes at the listening chair- they are certainly there in other places in the room! That's why I got a pair of the Swarm subs, just to break up the standing waves. The speakers can shake the organs in your chest and the cuffs of your pants and they don't sound boomy.

atmasphere:" I get similar impact on my speakers at home, which are flat to 20Hz. The problem I run into is a standing wave that causes a loss of bass on certain notes at the listening chair- they are certainly there in other places in the room! That's why I got a pair of the Swarm subs, just to break up the standing waves. The speakers can shake the organs in your chest and the cuffs of your pants and they don't sound boomy. "

Hello atmasphere,

     My main floorstanding speakers are 6'x2' planar-magnetic panels that only have a rated bass extension down to 35 Hz and also lack the ability to reproduce powerful bass dynamics.  I believe the ability of a home audio system to powerfully and accurately reproduce the bottom 2 octaves of bass and bass dynamics, like that heard and felt when listening to live music, are what distinguishes a good hi-fi from a high quality hi-end system.    These are the tactile and palpable qualities, along with a tonally accurate and detailed midrange and treble presentation with powerful dynamics and three dimensional stereo imaging, that are able to create the very realistic sound stage illusions in our rooms.
       The AK Debra 4-sub DBA system has proven to be an ideal bass supplement in my system and room, not only providing my system with the lacking deep and powerful bass and bass dynamics in the lowest 2 octaves but also doing so while seamlessly integrating with my main speakers.  And yes, it is capable of shaking the organs in my chest and probably the cuffs in my pants, if I ever become so dorky that I actually have cuffs in my pants. 

mijostyn:" If you but the subs against the front wall there is no early reflection point off that wall so only the floor and ceiling are comb filtering. On top of this you get all the benefits of a swarm system. Moving to the swarm as is normally used with say an 80 Hz crossover, to function as one driver the the subs would have to be within 8 feet of each other which is actually doable in most rooms. If you kept them all within 8 feet from one to the next what would happen? Tim, why don't you do that experiment and let us know what happens. I have no idea."
     
Hello mijostyn,

     From what I've read about bass line arrays and your description of yours, I have little doubt that it performs as well as you state it does, maybe even better than my 4-sub DBA in the right room.  I would love to try one or at least hear one in action sometime.  However, I think I'd probably need a more agreeable room and wife to do so. 
     I'd also be concerned about the effect it might have on the sound from my main speakers positioned in front of this solid bass wave and bass cancellation effects when this solid wave reflected back off my room's rear wall.

Later,
 Tim