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Room Acoustics Forum by Rives Audio Welcome! Need support, you got it. Or share you ideas and experiences. |
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Room Acoustics Forum by Rives Audio Welcome! Need support, you got it. Or share you ideas and experiences. |
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In Reply to: RE: Rob's room 3 posted by Ethan Winer on June 27, 2008 at 10:09:11:
As Ethan says, having things balanced at the front of the room is desirable because otherwise things can get pulled to one side.
Klaus said "Asymmetry results in the left-right ear signals being more de-correlated which in itself is a good thing because it improves the spatial impression. Asymmetry shouldn't be excessive though…" I think the point there is the bit about asymmetry not being excessive and I think different people will have different tolerance levels. Asymmetry certainly makes spatial aspects very noticeable once you hit your "excessive" level and start to notice left/right differences.
As far as Ethan's suggestion of symmetrical placement of absorption at the side wall first reflection points to reduce asymmetry problems at the side walls go, I am in almost total agreement. The slight 'fudge' I would suggest is having the opposite panels about 2-4" out of symmetry with each other. That's not enough to reduce the benefit of dealing with the asymmetries but you often get slightly more absorption benefit with the opposing panels slightly off-centred with each other. This simple trick can "buy" a little more absorption efficiency. If you have different speaker to side wall distances, you'll automatically get a bit of offset of the opposite panels if you space them the same distance from the walls and use the mirror trick to centre the panels on the first reflection points.
What Ethan did not comment on is asymmetry at the back of the room. I've got an L-shaped room with the toe of the L being behind my chair and to the left. That kind of severe rear of room imbalance also pulls the centre image to one side. I have a first reflection point on the rear wall for my left speaker but not for the right because the bend in the L shape blocks the path the first reflection from the right speaker would take if my room was rectangular. That loss of a first reflection from the right speaker on the rear wall pulls my centre image slightly to the left and needs to be treated with absorption or deflection in order to ensure the centre image is centred.
Basically asymmetrical room shapes will always cause some degree of L/R problem depending on room size and setup. Tracking down all of the causes for the imbalance can take you some time since dealing with the obvious ones can make such a big difference and get you ALMOST right as far as L/R balance goes and I find I have a tendency to relax and accept things at that point. It's also worth noting that you can get the L/R image balanced with the centre image centred and still have a sensation that there is more space to the room on one side than the other, a fairly subtle difference which I suspect may not be possible to totally eliminate but which can be very significantly minimised by paying attention to fine detail in tracking down issues.
I also think asymmetric rooms have some advantages, as well as the obvious disadvantages of L/R balance. One area of benefit is that they introduce more modal frequencies or weaken/broadband some modal resonances and that is often a plus for bass response and helping to smooth the room's response at a slightly lower frequency than would otherwise be the case.
David Aiken
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- RE: Rob's room 3 - David Aiken 14:43:47 06/27/08 (0)
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