I think there may be some disagreement on what "disappear" even means here. I think I'm more in agreement with
@olieb and
@Keith_W , though I basically agree with everything
@goat76 said, that being:
- A higher ratio of direct sound does - to my ears - create a more convincing stereo image.
- Getting that image is more a matter of setup, recording and room than it is the speakers themselves
- Basically all speakers can create a convincing stereo image if setup properly
Which is why I think I just disagree on what it means to "disappear".
For me, improving the stereo image usually comes at the expense of the disappearing act, and single speakers also disappear to some degree on their own.
I've basically got both camp's loudspeaker recommendations here, giant wide radiating towers and coaxial point sources. To my ears, and based on my idea of what those terms mean, the point sources image better, and the giant wide radiating towers disappear better.
Better imaging to me means: I close my eyes and draw circles around the images in the soundstage, and the smaller and more accurately I can define the area of those images, the better.
Better disappearing to me means: I close my eyes and try to draw an oval around the overall source of sound. The edges of the oval define my idea of "the source of sound is somewhere within this boundary". The bigger that oval is, the harder it is for me to pinpoint the source, and thus, the better.
The coax point source speakers create images that are maybe fist sized at end of arms length. As for disappearing, I can pinpoint the overall source of sound to an oval maybe 12ft wide and 2-3ft tall.
The giant towers create images that are maybe 1.5x extended hand sized at end of arms length, and disappear to an overal source of sound that's a few feet wider and about twice as tall.
The towers actually do a decent job(maybe like 3/10) of disappearing with just a single speaker in the mono. Closing my eyes and trying to pinpoint the overall sound source, I actually have to draw an oval with my arm/hand to fully encompass it.
The point sources hardly disappear at all with just a single speaker. When I close my eyes, I feel like I can fully pinpoint them with a single hand size. Part of me wonders if this is not the main reason speakers like this(ex: KEF) performed more poorly in Toole's mono listening tests than we would expect from their measurements.
The best disappearing speaker I've ever heard is the MBL Extreme at 3ma audio in Houston. Closing your eyes, it's like you can tell it's coming from somewhere on that side of the room, but not too much more than that. That said, the imaging was super diffuse and not to my liking at all.
Maybe I have the wrong idea of what it means for a speaker to disappear.