Creating a Large Sound Stage

@audiotroy 

We have found dual concentric designs like Kefand cabasse image extremely well

Spot on!  Speakers which emulate a point source of sound have far more coherent reflections than those with multiple separated drivers.  Once your ear/brain becomes accustomed to this effect, the difference is chalk and cheese.

I am thinking Quad electrostatics from the ESL-63 and later, which despite being big panel speakers, emulate a point source a foot behind the panel.  High-end KEF speakers like the Reference 1 do the same sort of thing.  My Reference 1 speakers easily throw a sound stage triple the width of the actual speaker separation.

Virtual line source speakers may do the same, but I have no personal experience with them.

In my opinion the only other thing you need is a good recording made in a natural acoustic environment, not a multi-miked studio recording with artifacts.  Almost any classical recording of orchestral music will do, especially if it is available on SACD.

Now that I've offended most Audiogoners, I might as well add that the difference between two-channel and multi-channel is another case of chalk and cheese.  Stop fussing over whether you can hear a miniscule change because of a power cord 'upgrade'.

To really experience multi-channel, visit 2L - the Nordic Sound where most of their recent recordings on silver disk are packaged with SACD (including CD, two-channel DSD, multi-channel DSD) and Pure Audio Blu-ray which includes high resolution PCM up to 9 channels and Dolby Atmos (up to 32-channels).  Don't even dream about streaming at these rates.

I hear this effect with only some recordings, particularly live orchestral music, so, clearly, it starts with the recording.  I recently changed my phono pre to the Sutherland Dos Locos (from the Koetsu RSP cartridge) and a number of LPs now exhibit the phenomenon of sound coming from the comers of the room, 8 feet behind and to the side of the speakers. 

Some hi-res digital recordings also do this trick, though to a lesser extent.  I think that a necessary condition is high resolution components throughout the chain.

It is not just channel separation as digital reproduction has a much greater separation than that of a typical analog level of 30dB.

The point made above about the recording venue and engineering is critical.  Forget it with multi-miked recordings (most DGs) and if you get it with studio recordings it has probably been faked with the pan-pots and phase manipulation.

@jimbennet 

All else being equal, a speaker that is coherent between drivers such that the diameter of a given driver has a bandwidth through the crossover that lets it broadcast its intended frequencies with as much horizontal and vertical dispersion as possible.  

The larger the diameter of the driver the more it becomes directional at higher frequencies. 

Proper phase alignment between drivers also creates coherence such that there are minimal drop outs or cancellations in the overlapping frequencies between woofer and tweeter for example. 

https://www.audiosciencereview.com/forum/index.php?threads/speaker-driver-beaming-frequency-formula.23816/

Concentric drivers can have some advantages (better meet directivity reqmts, etc) in multichannel rigs, in consideration how  formats like atmos works...but, it has its limitations.

When these 2 channel guys are talking about soundstage, precise placement, separation, etc, they are focused on parameters that pulled them out the music (a silly thing to do, had the opposite effect)...also why i was trying to use some word like envelopment, etc instead.

Spot on!  Speakers which emulate a point source of sound have far more coherent reflections than those with multiple separated drivers.  Once your ear/brain becomes accustomed to this effect, the difference is chalk and cheese.

I am thinking Quad electrostatics from the ESL-63 and later, which despite being big panel speakers, emulate a point source a foot behind the panel.  High-end KEF speakers like the Reference 1 do the same sort of thing.  My Reference 1 speakers easily throw a sound stage triple the width of the actual speaker separation.

Virtual line source speakers may do the same, but I have no personal experience with them.

In my opinion the only other thing you need is a good recording made in a natural acoustic environment, not a multi-miked studio recording with artifacts.  Almost any classical recording of orchestral music will do, especially if it is available on SACD.

Now that I’ve offended most Audiogoners, I might as well add that the difference between two-channel and multi-channel is another case of chalk and cheese.  Stop fussing over whether you can hear a miniscule change because of a power cord ’upgrade’.

To really experience multi-channel, visit 2L - the Nordic Sound where most of their recent recordings on silver disk are packaged with SACD (including CD, two-channel DSD, multi-channel DSD) and Pure Audio Blu-ray which includes high resolution PCM up to 9 channels and Dolby Atmos (up to 32-channels).  Don’t even dream about streaming at these rates.

@avanti1960 

Those who think their multi-driver speakers are coherent just have to stand up and walk around a bit.  How far can they move before their soundstage collapses?

It is not just the speakers that need to be coherent, it is that the reflections from the floor, ceiling and sidewalls also need coherency.

I have experienced huge d'Apolito arrays which completely lost their soundstage if I moved my head just a few inches up or down.  Funnily enough, they were designed with precision time-alignment to sound like Quad ESL-63 speakers, only presumably much louder.  But they could only time align the direct sound.  Quads keep their soundstage pretty much wherever you are