Having set up a
secondary system in a room of those dimensions, I can share some thoughts and experiences.
First, any ESL is going to be too large a speaker for that small space, especially if not treated. But even with a massive amount of treatments, the results could be unbalanced.
I even chose a coincident mid/tweeter (a coax driver) speaker because I would be seated so close, I wanted the soundfield to be coherent and pin-point sharp (it is a TV room primarily, so dialog clarity is critical).
If I were challenged to set up an ESL, I'd do everything I did in that room plus a bunch more stuff necessary to make a dipole speaker work. Such as also covering the front wall with a hanging carpet (offset from the wall by 4"), but then I'd also add trapping behind the carpet, like a 2x4' x 4" absorber, directly where the back of panels of the ESL would be pointed at.
I'd also hang heavy curtains, or yet more carpet and cover the front 1/4 of the sidewalls of the room, the goal here is to tame any reflections from the rear of the ESL, reflecting off the front wall (yes, the carpet will absorb a lot, but not everything) and then bouncing off the side walls.
It is this side-wall reflection that impacts the 'sweet spot', and the lower the level of reflections, the wider the sweet spot, as you are now listening primarily to the sound coming from the front of the panels.
Since the room is so small, not much space for bass-trapping, but if necessary, it can be done on the ceiling. However, I found that the quad sub setup I used resulted in excellent bass performance, even with zero bass traps. So I'd suggest adding two small subs at the rear of the room, run the Ethos full-range, and feed a speaker-level input to the subs, and set their crossover at 70Hz. Lower the output of the Ethos bass, and set the levels of the rear subs fairly low, as we're doubled up on low-end. Then use the room corrector or EQ in the preamp to balance it all out.
There, simple answer
