Originally Posted by Chef
That means you can hear in front of you, and to the left and the right.
But: not behind you, or, from above or below: that would be 6D.
I'd vote Aguilar DB680. I love that thing.
I'd sign on to that definition. But since I just formulated my own version
, here what I would add to describe 3D: detailed, with the ability to hear different frequencies clearly defined; having a good aural 'soundstage,' in which musical notes are presented distinctly and with depth. This tonal feature is what I like, for example, about my 1970 Blueline SVT and Alembic F-1X, and what I didn't like about my Markbass F1, SWR Electric Blue, or Yamaha PB-1.