[JohnR]

Is it "real"? Or is it an artifact of room acoustics?

If it's "real," are you finding it occurs more on acoustic recordings or electronic/studio recordings?

In any case, how do you have your speakers toed (forward, at you, cross-eyed)?

[SWG255]

I find this is one of the real variables in my listening experience. I don't have an ideal listening room and I am almost in a "near field" position in regard to my speakers. I will say that some of my SACDs exhibit a much wider soundstage than their standard CD couterparts.

[Pez]

Imaging can be "thrown" out side of the speakers.  It is due to the perceived time and phase differential that is presented from the left and right speaker. This tricks the ear into believing there is ambience and even instrumentation virtually anywhere in the room.  A truly capable system can even trick the ears into thinking there is vertical and horizontal position.

[JohnR]

Imaging can be "thrown" out side of the speakers.  It is due to the perceived time and phase differential that is presented from the left and right speaker.

Where is the time and phase differential coming from?

[Pez]

The difference is coming from the left and right speaker. If you imagine for a moment a bird behind you to the left.  The left ear will here the bird before the right ear by a micro-fraction of a second. The brain sums the two and take into account phase (the fact that it's coming from behind you) allowing you to perceive that the sound is indeed coming from behind you to the left.

Now if you take the same example and apply it to speakers you are able to trick the ear into hearing sounds anywhere in the room.  

If the bird is to be presented in the same location as the above example the timing would have to be something like this:

left speaker sounds at 0 seconds, right speaker sounds at .05 seconds (BTW I'm making the numbers up they probably do not correspond at all) left speaker presents sound in phase, right speaker presents sound out of phase.  This would place the bird behind you and to the left I believe. In this example if both speakers were in phase with each other the bird would sound like it was in front of you to the left.  If the speakers were timed to sound the bird at the same time but out of phase the sound tends to be either disembodied or behind you.  (Don't hold me to any of this. I believe the concepts are correct, but I'm not sure about numbers or what speaker has to be out of phase to create the illusion)

One of the biggest factors is precise spacing and even more precise toe-in.  If the speakers are off by even a little bit, much of the effect is scrambled.

[Pez]

Where is the time and phase differential coming from?

One other very important piece of info is that everything I discussed above must be present in the recording. Obviously if your recording is not presenting sound outside of your speakers you will not get sound outside of your speakers. That is unless you have a lively room.

[cyounkman]

One of the biggest factors is precise spacing and even more precise toe-in. If the speakers are off by even a little bit, much of the effect is scrambled.

Another important factor is the phase coherence of the speaker in question.  (Many are phase 'incoherent'.)

[gonefishin]

Hi John.  Like Pez has said.  Imaging outside the speakers is real...well, kinda.  The sound, obviously, comes from the speakers...but the recording engineers use certain methods to "trick" us into thinking the sound is coming from somewhere else.

   My old system had a huge soundstage...it would almost wrap entirely around you at times.  In my experience a wide soundstage is influenced by the recording, the speaker positioning, the speakers, the source player and the amp/pre.  One thing you don't want to do is position your speakers too wide...or too forward(for that speaker)...you may loose your imaging & soundstage in between the two speakers..

  As for forward facing or toed-in to get the widest soundstage...it really depends on the speakers/system/room.  Mine worked very well just shy of forward facing.  While my old system/speaker did very well in the soundstage/imaging department...The silverline sonatina's did this even better.  Set up properly these speakers can be spooky good.


   John...why do you ask?  are you just curious or are you working on something?

[Pez]

Another important factor is the phase coherence of the speaker in question.  (Many are phase 'incoherent'.)

 

Strangely enough I have to disagree with this.  I have heard many properly setup "phase incoherent" speakers image well outside of the soundstage.  What is important is that the speakers be phase coherent with each other.  If they are not presenting similar phase characteristics then you will have an unfocused soundstage and image which will definately not allow outside imaging.

[cyounkman]

Another important factor is the phase coherence of the speaker in question.  (Many are phase 'incoherent'.)

 

Strangely enough I have to disagree with this.  I have heard many properly setup "phase incoherent" speakers image well outside of the soundstage.  What is important is that the speakers be phase coherent with each other.  If they are not presenting similar phase characteristics then you will have an unfocused soundstage and image which will definately not allow outside imaging.

I guess that's true--since 'phase coherent' refers to coherency between the drivers of a single speaker. The midrange drivers of two [self-] incoherent speakers can still be in phase with each other, allowing the imaging tricks in that range. But the imaging tricks will be somewhat bandwidth-specific, since you have different phases coming at you in different ranges. (One more reason to keep crossovers out of the critical midrange; or better yet, to use 'perfect' digital x'overs)

As usual, though, the proof is in the pudding, not the design brief. I'm sure there are non-coherent multi-ways that throw a very natural image.

[John Casler]

As I mentioned in another post, in my experience, "outside speaker" perceptions are of two types:

1) Sidewall reflections (will not happen in a totally anechoic chamber)

2) Phase relationships present in the recordings as mentioned by those above.

Q-Sound and other techniques are deliberatly engineered this way.  I am unclear as to "if" a specific type of miking arrangement can "pick up" these phase anomilies naturally during the recording process, or if they are added, or accidental to the process in some cases.

As far as my "toe in" I use a precision aligned "on axis" nearfeild listening set up, with speakers 4-5 feet out from the front wall and about 10 feet apart.  This is with a 7-8 foot (from the face of the speaker) listening position.

I am also 6-7 feet from the back wall.

One thing I used to always find interesting in some of the Stereophile and Absolute sound reviews is their "claiming" that the amps/preamps/speakers they were reviewing "increased" soundstage outside the speakers.

Aside from them increasing dispersion for greater side reflection (speakers) or the amps/preamps changing, recognizing or adding phasing information I don't see how that is possible from a psychoacoustic standpoint.

As far as "image height", I would say it has to do with the average height of the drivers and ceiling reflection.  There might also be a bit of phase relationship since different drivers are in various phase relationships in the vertical axis.

I know that when I switched to the RM40s from tha Legacy Sig IIIs the image height increased.

[Pez]

John good points but what you are refering to is the characteristic of the particular speaker when talking about speaker height. It is true that some speakers project image and soundstage at different heights. The way speakers project image/soundstage is somewhat of a by product of the design. What I was refering to was something different. Actual shift in image and soundstage hieght can be attributed again to psycho-accoustics.

This phenomenon is almost impossible for most systems to do accurately. The human ears are not exactly the same shape, position, etc. This intentional mismatch allows us to tell if a sound is coming from above or below us.  It actually has to do with the brain measuring the slight difference in timing and character of sound (if your left ear is slighly lower than the right ear the timing will be different).  

The ear is much less sensitive to vertical sound than to horizontal, which is why you can place a speaker above or below your TV and for the most part it sounds like it's coming right from the TV. Lay down on your side and instantly the illusion is lost.  In essence vertical illusion is hard to achieve due to the inaccuracies of the ear.  However the illusion is strongest when the ear is able to compare relative pitch and sonic character.  There are a few setup cd's out their that allow you to test your systems vertical image/soundstage.  The vertical section uses computer generated tones that change in character ever so slightly, tricking the ear into thinking the sound is rising slowly. It's pretty cool and can tell you quite a bit about your individual systems capability.

[JohnR]

Where is the time and phase differential coming from?

One other very important piece of info is that everything I discussed above must be present in the recording. Obviously if your recording is not presenting sound outside of your speakers you will not get sound outside of your speakers. That is unless you have a lively room.

I guess this is what I'm asking. Is it present, barring tricks like Q-sound?

[Pez]

It can be depending on the recording quality.  I have heard some live recordings and some studio recordings that have great imaging and soundstage outside the speakers with no post-production trickery.  Again it requires excellent recording method and a lot of knowledge on the producers part.

[John Casler]

Anyone have any specific cuts or CDs that demostrate this other than the Q-Sound stuff?

brian played me a cut from some Jazz CD that seems to have it, but I didn't see if it had a Q on the jacket.

[michael w]

Try well recorded classical music such as the Classic Records RCA re-issue LP's.

Eg. Reiner/CSO's  Lt. Kije, Scheherazade; Ansermet Royal Ballet Suite; Witches Brew.

For jazz there's always the old chestnut Jazz At The Pawnshop as well as evergreens like Miles Davis' Kind Of Blue and Brubeck's Take Five.

Pop/rock; try Roxy Music's Avalon, Dire Straits Love Over Gold.

No guarantee that you will get the same sort of soundstaging from the CD versions though.


cheerio

[TG]

Is it "real"? Or is it an artifact of room acoustics?

Just to make things more confusing, it can be quite amplifier dependent.  My solid state amp creates a very strong central image, whereas my OTL valve amps create a more widely spaced image which doesn't extend far beyond the speakers.  My 300B SETs, on the other hand, create a huge soundstage with aural images conjured far past the speakers - maybe it is related to large quantities of low order distortion in the signal?  Maybe it's a synergy thing between certain speakers and certain amps?

Cheers

[doug s.]

in my experience, the room is the biggest contributor.  unlike mr. casler, i believe sidewall reflections will kill most illusions of sound coming for outside the speakers.  this has been my experience, anyways...  if my speakers were close to sidewalls, the 1st item on my agenda would be sound absorption at 1st reflection points.

my present set-up affords me the luxury of having basically *no* sidewall reflections, as the speakers are in front of a ~26' wall.  i get sounds from outside the speakers, regardless of the speaker, regardless of toob or s/s amp.  source material is the most relevant factor here.  i even get lotsa outside-the-speaker sound from my fm tuna!     as far as amplification goes, this seems to affect soundstage depth, more than any other soundstage cue, tubes being best at providing a deep soundstage.  having the speakers 6' from the back walls also helps here.

doug s.

[gonefishin]

To me...creating an audio image outside of the speakers is really the same as creating an audio image dead center of the two speakers.  Both trick you into thinking your hearing sound come from a source other than the speakers.  

    I'll add a few interesting web sites you may want to check out.

  also, you may want to start looking for some recording engineer forums...they would have more info for you on this topic.


   All in all...our brain plays tricks on us so we can tell where a sound is coming from...and so we don't go crazy from all the reflections that are present...our brian will actually cancel out some of the sound that enters our ears.  It basically acts as a type of sound processor.  Stereo music doesn't really plays any tricks on us but stereo music does take advantage of the tricks we play on ourselves.

 

http://www.dpamicrophones.com/eng_pub/

http://www.york.ac.uk/inst/mustech/3d_audio/ambis2.htm

http://www.york.ac.uk/inst/mustech/3d_audio/ambsnlct.htm

Our recording technology is equally radical. We design and build, or custom-modify, all of our electronics from microphones to tape recorders to wires. All must meet standards well beyond commercial state-of-the-art. We record live to two-track analog, transfer to digital at a rate 100 times faster than the CD standard, and use no add-on EQ, reverb or noise reduction electronics. Our recordings are made with only 2 to 4 microphones and no cables longer than 20 feet. The resulting sound has startling, "in-the-room" clarity, brilliance, spaciousness and dynamics. People with $150 boomboxes, as well as audiophiles with $100,000 systems, tell us our CDs convey far more of the music's excitement than any commercial studio recordings. Mapleshade has 40 current releases and many more in the can waiting to be released. These albums document the music of more than 175 musicians including both noteworthy new talents and established artists such as Randy Weston, David Murray, Woody Shaw, Gary Bartz, Larry Willis, Hamiet Bluiett, John Hicks, Clifford Jordan, Walter Davis Jr., Leon Thomas, Drink Small, Sunnyland Slim, Slide Hampton, and Shirley Horn.

   This is a little blurb mapleshade has written about it's recording techniques...The soundstaging on all of the albums I have purchased thru them has always been superb.

[KevinW]

Is it "real"? Or is it an artifact of room acoustics?

If it's "real," are you finding it occurs more on acoustic recordings or electronic/studio recordings?

In any case, how do you have your speakers toed (forward, at you, cross-eyed)?

John,
Imaging outside the speakers can be a real acoustical effect.  It depends on using the proper microphone.  I can't remember the exact name of the mic that has the proper polar sensitivity pattern, but I'll edit the post when I do...

If two mics have a figure-eight polar sensitivity pattern that are laid down on each other in a "cross" geometry, then the necessary phase information to get imaging outside the speakers can actually be recorded. Think about it...  and your homework assignment is to get back to me with a laymans explanation of how this actually works.  I have a physicists intuition that this is correct, but my english language translation faculties are a little blurry this morning.