Hi Satch,
Yes, these types of open plan primary living are a real challenge to deal with. When trying to fit a speaker system that not only has large radiating surfaces, but does it front and back.
The first goal is one of trying to achieve balance. As you note, your soundstage is so lopsided, you need to compensate with level adjustments in the preamp.
This tells me your room is proving more reinforcement on the left, since you have a wall and associated corner in the front left of the room, but none on the right, that makes sense.
The left channel rear wave is hitting the front wall and reflecting at an angle onto the left side wall and then back into the listening area. The right speaker is getting no such help, as its rear wave, once it bounces off the front wall travels off into your kitchen, where it’s pretty well dispersed before any of it comes back into the listening area (and much more delayed).
Not only does this affect mids and highs, it affects the bass as well, as the left front corner is helping some of the bass frequencies, but the open right side is not.
The answer therefore is to try and balance out the front stage by ensuring that the rear waves are better balanced. We’ll get to how in a bit.
The other thing affecting your soundstage is possible left side wall reflections from the front wave, but looking at your toe-in, I’d say it might not be very significant. But it wouldn’t hurt to experiment with some absorption on the left wall at first reflection points for the front wave.
On the right, nothing to worry about, as it’s open, right?
The other concern is your seating position is very close to the rear wall, and again there’s an asymmetry to deal with. Your right ear is perceiving rear reflected sound from the bookcase, so it’s slightly diffused and delayed less than the reflections from your left, which will be sharper (no diffusive surfaces) and slightly longer delay (2ms or so)
Ok, so how to deal with all this?
It’s not going to be easy, and it’s going to take a good bit of DIY or commercial room treatment products to do this right, but it will seriously improve the balance and frequency response of the system.
I’ll use commercial tool names and descriptions (from
RealTraps), but feel free to substitute equivalent DIY solutions, so long as they really perform in terms of broadband absorption.
First, the front wall. Even though we’ve identified the problem as being focused on the left front, I recommend you treat both left and right halves of the front wall equally. This will maintain not only vsual symmetry, but acoustic symmetry as well.
The most important thing to do is to provide trully broadband absorption. The auralex and DIY panels depicted are doing very little below 500 hz (if that). What it will take is the equivalent of two MiniTrap HF’s and one Mondo trap behind each speaker. The minitraps are placed vertically, side by side, absorbing the primary rear reflections from the panels. The Mondo is laid horizontally just below the Mini’s to provide deeper mid-bass and bass absorption. All these products are offset from the wall by three to four inches (to improve bass effectiveness).
This will pretty much deal with the majority of the rear wave. But we still have some lingering effect from the left corner and wall. So I’d add a pair of mondo’s straddling the front left corner (if they fit between front wall and side wall / door). This will provide additional bass trapping that will further balance the fact that the right side is open.
As noted above, look into treating the first reflection on the left wall, a 2x4’ microtrap might be all it takes.
And finally, the rear wall. I’d add some minitrap HF’s (as we need to damp the high-frequencies as well), placed horizontally, centered on the seated head level. This will improve the imaging from the front, as it’s not being interfered by such short (<10ms) reflections from the rear wall.
Optional, extra credit would be to add another pair of Mondo’s stacked int eh left rear corner, to help in general room bass management. Again, helping balance the open right side.
All this bass trapping will not only help your stereo, but should vastly improve your practice sessions with either the acoustic double bass or the amplified bass.
Anyway, I’ve rambled on long enough about all this. Please accept this as just my humble opinion and I hope this helps.
