The illusion of soundstage.

No offense but that explanation Re two waves interfering etc. Is either incorrect or incomplete since you can under good circumstances get a reasonably good soundstage with a mono recording and a single speaker, for which there is obviously only a single wave. I'm not saying there isn't interference between the left and right channels in stereo I just don't believe that explains how we get to the point of a great soundstage. I suspect there are many reasons for great soundstage, including but not limited to, noise and distortion produced by jitter or mechanical vibration, magnetic field interference, scattered laser light in digital, seismic vibration, interconnects and fuses in the wrong direction.

A number of the responses got it correct...  It is a function of wave theory and the fact that what you hear is not a single wave.  It is the complex interactions of 2 sets of waves arriving at different times to each of your 2 ears.  Right and left speakers waves (actually oversimplified since most speakers have multiple drivers) interact with each other.  

The behavior of waves; interference patterns, comb filtering, nodes/anti-nodes, etc. impact the sound level and timing that each of your ears perceives.  Your brain then "steers" your perception of where the sound appears to have originated.  Functionally, light and sound waves behave similarly so if you want a visual, google light interference pictures.  The most extreme example of this effect is with noise cancellation headphones which creates a perfectly out of phase sound to the actual noise and the two waves completely cancel each other out.

The degree of sensitivity to timing delays between your ears becomes evident when you are swimming under water.  Because of the density of water being greater, the speed of sound increases and therefore the delay between your two ears becomes shorter.  As a result, human beings more or less can not decipher directional clues from sound underwater...  Gives us a few million years under water to evolve and we would likely "recalibrate" and be able to decipher those clues.  Dolphins, wales, and all other sea mammals have similar ears to humans and other land mammals but they all relay on echo location to "see" more than eyes.

In summary, if a louder sound wave originates from the left speaker and a softer identical, but out of phase, wave originates from the right speaker, our brain will interpret these waves as if the sound was originating from outside left of the left speaker.  As one respondent correctly states, Q sound accurately maps these interactions and sound engineers can actually steer the sound not only to either side of the speakers, but even around your head.  For this effect to be completely realized, you must be sitting in the "sweet spot", equal distance from the two speaker... and of course above water level...

Altering the relationship in time of one frequency to another is quite easy to detect with the right tools. It's quite easy for you to measure using something like Room EQ Wizard as well. However almost all of this is caused by the speakers themselves. I've seen no evidence that the most basic and common of amplifiers introduce any phase shift at all. 

In any event, if this were true, then tools like Dirac Live or RePhase+miniDSP would be able to compensate for it completely. 

Best,


Erik 

     I had some excellent Classe equipment given to me, two Classe preamps and two amps. One amp was 350 wpc ad the other 150 x 6 or 300 x 3. The preamps were their soul/marketing mates.
     One channel of the stereo amp was out due to blown fuses.
     Interestingly, the single channel had a huge sound stage. From a 35 year old B&W DM 14, a model known to center the sound between speakers, and the sound was all over the room. I can't imagine anything other than a design of contrived electronics that caused this.
     I never even tried the Classe pieces on my B&W 803's because my pair of Audire amps and preamps sound much better, with precise location of the instruments in space.
     Having said that, off course speakers send a larger sound than their driver width!  Speakers radiate outward in a cone. They are not lasers.
     

I am repeating what I've heard from Roger Paul as an explanation for the quite wide, deep, and high sound stage I hear with his X-10 MkIII amp used with his X-10 line stage.

Apparently, every amplification stage passes some frequencies through faster than others. This means that even the best speakers are asked to reproduce all music with out of phase frequencies. Somehow he can sense this happening and assure that all frequencies pass at the same time.

The results are a sound stage with great realism, clear sense of room boundaries, player noises, clear decay of notes, and presence of performers. I suspect that my BMC Arcadia front and back firing speaker can reproduce all frequencies as they were recorded. 

The H-Cat components, speakers, HFC cables, Archiving Vinyl music server, and Tripoint Troy Signature all contribute to what thrills me on every album.

tostados, agreed, the engineer 'sets the stage'...virtually, but that's the modern recording studio for ya....not to mention the other 'enhancments' that can be dialed in.

I suspect that given current tech might allow a certain level of 'ambiance' in a mono recording that comes through with a high quality system, but I've never had the pleasure to hear such.  On the other hand, I'm not disposed to go looking, either...*G*

I know little-to-nothing about much of this discussion but I know what Wolf Garcia said is absolutely true.  IIn a stereo recording it all starts with the image created by the engineer's panning of the individual tracks/channels/mics. 
As to soundstage presentation in a mono format--I don't get the concept at all.

Right, comb filtering is also created when sound reflects off a side wall and travels 2 different distances, that's why lack of acoustic treatment can ruin the spacial information. 

ahhhh! now i see. comb filtering dammit. that is great info guys! so its really all in my head , literally. makes sense. i knew there was more to it than simple external physics of sound waves, our ears are not the instruments we think they are. or at least not the simple conical sound gatherers with no other factors coming to bear.

Wait, wait wait! :) HRTF is a real thing, that being said, I'm a huge believer in acoustic treatment and bass traps. If in doubt, call GIK Acoustics for a consultation.  

Not only do their panels work wonders on imaging and smooth great sound, their soffit traps have enabled my subwoofer and 2 way speakers to play to reference quality. I have so much lyrical, smooth and strong bass I can use music to treat kidney stones. :)  Soffit Traps FTW!! 

erik's got it sussed, and geoff's got the clues....HRTF is why headphones work so well, and the 'ambient' (whether real or 'created') is what we experience with any given pair of speakers to a greater or lesser degree.  And then we devolve into where and how our speakers are placed in a given space, what the space consists of  (what's in it, what's not, how that's arranged, hard/soft surfaces/materials, ceiling height, width/depth, toe-in/toe-out (sounds like Arthur Murray to me, two, three, four...), what you've drunk or not, etc., ad infin...

You either go bonkers with creating the 'perfect' space, which will Still be a relative rationalization unless you're an audio engineer with a talent for spatial calcs of a mind-breaking sort and a better than modest budget OR you can 'ignore the room' (per Linkwitz) which is where I'm at (it's a leased space that I can't go nutz in, and I'm cheap) OR you can do the best you can with whatcha' got with the furniture that's there and the SAF.

In the nutshell most of us occupy, that's the devil's deal.  My omni's complicate the issue, given what they do in a given space.  So I play with active eq, a tad of delay, and strike a deal with the space which is Very 'Live' (everything is 'hard' and unforgiving...).

It works well enough.  Been in worse, been in better....

Look up head related transfer functions.  Short explanation is you never hear a flat response.  Sounds that reach your ears from different directions have comb filtering effects, which your brain interprets as direction.  If you can fake those effects through sigmal processing you can fake the direction.

So what i really was looking for was how, physically, sound waves can appear to be originating from outside the width of the transducers. i can imagine with an electrostat... but in phase or not, how does the wave(?) appear to come from  a different place. i am a visual thinker and want some sort of representation in that sense. thanks for all of the replies btw

The ambient information of the recording venue including reverberant decay, echo, first reflection and other subtle queues are captured in the recording thus two speakers can reproduce this information. Thus, depth, width and height dimensions, the 3D sphere or cube of the location as it were, should theoretically be reproduced (on a capable system). One might have to struggle a little bit to extract all the ambient information from the recording that’s there to extract but theoretically anyway it’s there.

Head Related Transfer Function. :) The secret is how your head, ears, and hair affect incoming sounds from different angles. It’s more than just amplitude and simple phase. Your body adds comb filtering your brain picks up on to determine vertical and horizontal angles. Very cool science.

Having said that, to get good sound staging in any dimension you must have good room treatment in that direction. So, if you want good left to right soundstage, you should have good room treatment to the sides and behind the speakers. If you want height, good treatment above the speakers.

There’s a known speaker gimmick. Dipping the frequency response around 2.4 kHz will exaggerate the sense of imaging. You’ll see this in a number of "high end" speakers.

Most of the times I've heard this effect by the way it seemed like an accident, as opposed to a real attempt by the recording engineer to do something. Intimate jazz quartets for instance. 

Pan pots used to any degree by any recording engineer are the secret…pan left, pan right, or no pan at all.

I think a wider soundstage is a result of proper setup for I have yet to hear a pair of speakers that do not pass beyond the drivers. Ex: with Dyn's I found very little to no toe in extends the soundstage way beyond the speakers and still retain great imaging but somewhat close to each other. Toe them in and the imaging gets a hair better but looses the wide soundstage. Raidho/Scansonic on the other hand require a farther distance apart but with a fairly severe toe in. No toe in creates an even wider soundstage but then severely looses the imaging.

Or, in my case and situation, I'm running Walsh drivers which are omnis.  I've a 'soundstage' that 'extends' not only to the sides but also in front and behind the drivers.  Placement within the given space and the surrounding objects (or lack of same) will certainly effect 'the effect'.  I've also noted that from selection to selection, artist to artist, album to album there's distinct differences in what is perceived where.
Adding a second pair, either in 2 channel or 4 channel arrangements, and playing with delay or no, you can be sitting 'on stage' or row 5....
But 'immersion' isn't to everyone's taste.  To each...

If you put your drivers out of phase with each other you will get sound all over the place. Q-Sound is software that manipulates phase to put sound beyond your speakers , even behind you
Alan

Sidewalls were (and still are) about 6 feet on one side and the 1st reflection point on the other side doesn’t exist since there’s only 3 feet of the side wall extending out from the front wall before it gives way to being open to the rest of the house. I have only owned monopole speakers, but I really noticed that a portion of that uber-wide effect wound up being curtailed just a bit once I switched from that DAC to a (overall better) CDP. That DAC was good at scrunching up the soundstage toward the zone in front of the speakers...something I was not really shooting for, despite its own advantages. (If you’re into the very forward presentation thing, that DAC probly would’ve sounded great with a Grover Huffman loom!...DAC is an EVS-modified Behringer DEQ2496).

In my quest it has also been a give th and taketh away scenario. In looking for more depth I lost imaging width and settled for a middle ground. This was done moving speakers in and back and wider and narrower. So room and speaker interaction. The rest of chain certainly contributes but less. Except in my exp. tubes do seem to synergisticly encourage a bloomy boundarylessness that I like. 

Ivan,  5 and a half feet! How far out are sidewalls?

I imagine you could think of depth itself as a direct result of width in 2-channel playback. 2 speakers are already casting, according to their dispersion patterns, a given width into the room...where those patterns tend to overlap the most is where you get the most depth...yes?? So, to me, width is sort of the precursor, if you will, to depth...it's all the influencing factors of room, gear, etc that dictate how much or how little of depth or width in a given setup we can attain.

But if you are looking for some inherent cause, I would start with the dispersion capabilities of the speakers (perhaps especially the drivers) and, as well, the soundstaging of the associated gear and/or wiring. And it may take an unbroken string of an alignment of these factors to achieve a particular desired result - from source to room.

I've had speakers that, with the particular DAC I used to have, could image a full 5 and a half feet outside the cabinets, albeit at the expense of some depth, most especially at the rear corners. Now, I kinda have the opposite...only a foot or so outside, but with uncommonly good depth all around.

My understanding is that this is a complex question. Largely, the effect is a function of how the speaker interacts with the room. You can experiment with this by moving your setup around ...even into another room. Does it sound the same? Probably not. 

Toe-in of the speakers will narrow the soundstage, as will in my experience having the speakers too close to side walls. But, frankly I did not experiment much in this regard.

Have you shot your room with, say R.E.W.? That's a nice piece of freeware that runs on, say a laptop. You will also need a good quality microphone for this purpose ($50 or up), a microphone cable (usually a balanced cable with these mics) and an analog (balanced in) to digital (usb out) converter (I got one of several in the $200-500 realm. I think this is a very worthwhile thing for an audiophile to do unless you have far better ears than I have. You will thus have the tools to explore the invisible world of what your room does when it interacts to specific frequencies from your speakers. (I ended up moving speakers and pasting damping sobathane on the back of artwork, a mirror, the inside of a modern floor lamp,...)

Out of phase information on the record/cd will appear to come from beyond the boundaries of the speakers. In phase information will appear only between the speakers - unless you are getting a lot of side wall reflections which can give the illusion of a wider soundfield (you also lose some fine resolution that exists without the reflected information added).

Some manufacturers have made or altered equipment by playing with the phase relationships to make the soundstage seem wider than it can appear in a properly set up system of traditional equipment. This can be accomplished in speakers as well as electronics.