symmetry in unbalanced room

[MaDHaTTeR]

If you have a slight L shaped room, and the bottom of the L is behind the mix position, is it better to center your speaker placement based on the front half of the room, or the wider part of the room behind you?
The L begins about halfway.

The first reflection points would be in the narrower section of the room, so for the sake of symmetry, that would seem like the obvious choice.

But, since the back half of the room is wider, if you're treating the first reflection points with absorption, maybe the symmetry should be based on the rest of the room, keeping other reflections in mind.

If this is difficult to visualize, I can draw a quick pic in paint.

thanks,
MH

[avare]

The narrower section. Low frequencies still follow a wave development from the speakers and the symmetry is necessary for low frequency imaging.

Symmetrically:
Andre

[bpape]

Agreed. Symmetry in the front of the room is very important. Shifting off to one side will cause a lot of time related issues.

Bryan

[MaDHaTTeR]

So the reflection free zone wouldn't save the listener from all the issues an off center mixing position would create, in the front half.

Thanks for both the responses.

Follow up:
Does the left wall being a closet for the entire length of the narrower front half, raise any concerns? Sliding hollow wood doors take up about 80% of the surface area. This is what creates the slight L shaped room.
I'm wondering in terms of low frequencies, and again, the symmetry/imaging.

Cheers,
MH

[Ethan Winer]

Originally Posted by MaDHaTTeR

So the reflection free zone wouldn't save the listener from all the issues an off center mixing position would create, in the front half.

Having absorption panels placed symmetrically at the side-wall reflection points will indeed help to preserve left/right imaging. But it does so only to as low a frequencies as the panels are effective. So using, for example, 2-inch thick rigid fiberglass panels will make imaging symmetrical down to maybe 500 Hz, but not at lower frequencies.

Sliding hollow wood doors take up about 80% of the surface area.

Again, this might have an effect at certain low frequencies. But in the grand scheme of things I see no real problems with one wall made of hollow wooden doors and the other made of sheet rock. As long as you have reasonably thick absorption at the reflection points, that will fix a lot of other ills.

--Ethan

[MaDHaTTeR]

That really was the deciding factor. Would absorptive panels configured for a RFZ sufficiently correct the side effects of an off center mix position. If they would, then why not center the mix position based on the back half of the room, as that would more evenly balance the information coming back. (L shaped room)

Avare and Bpape seemed to be saying, regardless of any absorption panels in place, stick with a symmetrical mix position based on the front half of the room.
Whether they were strictly referring to low frequency imaging or not, I have no idea.

Are you disagreeing with them?
If the panels at the first reflection points were adequately absorbing the lower frequencies, you're saying there shouldn't really be concerns about imaging at the off center mix position?
(I assume in your response, the "symmetrical" first reflection panel placement is based on the room width, and not the off center mix position)

I've also questioned potential benefits of a slight off center mix position, due to articles such as your very own "how to set up a room", where you mention that dead center is never ideal, front to back, side to side, or top to bottom.
I was wondering about distances of 5 to 10 inches off center. (total front room width of 11' 10")

thanks,
MH

[Ethan Winer]

Originally Posted by MaDHaTTeR

Are you disagreeing with them?

It's impossible to agree or disagree because so far I haven't seen a floor plan or even a photo of your space. So at this point it's all theoretical. But I'd never disagree with symmetry as the goal. Whether that's practical for you is another matter! So then the job is to come up with the best compromise.

I've also questioned potential benefits of a slight off center mix position

I once asked my friend and studio designer Wes Lachot about this. He said he prefers being centered to being off-center even a little. This is one of those things where different competent authorities might disagree, yet neither would be wrong.

The best approach is to measure the response. Then you'll know exactly what the trade-offs are.

--Ethan

[MaDHaTTeR]

The main purpose of the theoretical route beforehand, was to try and avoid making several sets of holes in the ceiling, for cloud placement.
Measuring at different mix positions would be fine, if it didn't require damaging the ceiling unnecessarily.
Wouldn't measuring response at the mix positions without a cloud skew the data?

As I said at the beginning, L/R wall symmetry for the mix position would be the obvious, but contemplating the room shape, the left wall being a closet, the RFZ, etc, alternatives seemed worth considering. Where better to discuss the possibilities than the new acoustics forum?

And of course I wasn't suggesting you would disagree with symmetry as the goal.
I was asking if you were suggesting that imaging/balance would not be compromised, if there was sufficient broadband absorption at the first reflection points. (when the mix position was not symmetrical to the left/right walls)
My interpretation of bpape and avare's responses, was that the RFZ wouldn't adequately protect the mix position from the issues.

I should point out that we're probably talking no more than a foot off center at most, with any of this. (front half of the room's center)

Interesting story re: Wes Lachot.
What do you prefer?

cheers,
MH

[avare]

Originally Posted by MaDHaTTeR

My interpretation of bpape and avare's responses, was that the RFZ wouldn't adequately protect the mix position from the issues.

If you want it with no interpretation, "Symmetry is the most important thing in acoustics around the stereo monitors."

Clearly,
Andre

[LittleJohn]

a picture would be worth a lot , I think I have the same issue (question ) but would like to be sure...

[bpape]

Symmetry is important in front of you. Yes, panels may only go so low but being symmetic to start with preserves it no matter what the reflection panels do. Being off center a little (6" or less) can help with width related modes. Whether its worth it or not depends on the specific situation.

In an L shaped room, it's usually a LOT more than that so the theoretical answer is to stay centered.

Bryan

[Ethan Winer]

Originally Posted by MaDHaTTeR

Interesting story re: Wes Lachot.
What do you prefer?

I don't have a strong opinion either way, but the best compromise from my perspective is to be maybe a half a foot off center left and right based on the rigid outer boundaries of the room. Then place the first reflection treatment equal distances from you left and right. Or have a cardboard inner wall on one side. The idea is to be off-center at bass frequencies, and centered at mid and high frequencies.

--Ethan

[MaDHaTTeR]

Bpape: Even if it doesn't apply to this situation, it's useful knowing the off center approach actually is put into practice at times, and the range limitations, so thanks.
When scenarios do dictate the benefits are worthwhile, what's Your approach for dealing with the slight L/R wall asymmetry of the new mix position?

Ethan: If it would actually require some sort of artificial wall, or moving the panels out further from one wall on stands, then it wouldn't be very practical in this space. Thanks for the feedback.

Avare: succinctly, thanks.

LittleJohn: Yeah, far too much typing. A pic is no problem. I'll post one later on.

At this point, I'll just keep the mix position centered and also possibly move a large wooden storage cabinet into the 5th corner, somewhat extending the left/right symmetry further to the back of the room.

MH

[MaDHaTTeR]

[bpape]

Slight assymetry as I described is treated similarly to a symmetric layout - but your side reflection panels may need to be offset from each other to accomodate the new reflection points.

Realistically, reflections are really more areas than points but covering the points themselves certainly helps a bit if you can.

Remember that seating location, monitor location in relation to the wall behind them and the wall beside them, and the way you treat directly behind the monitors are all usable items in tuning your bass response.

Bryan

[MaDHaTTeR]

Originally Posted by bpape

Slight assymetry as I described is treated similarly to a symmetric layout - but your side reflection panels may need to be offset from each other to accomodate the new reflection points.

Not to drag this on, but when you say offset, do you mean in the same way Ethan suggested in his last post? (moving one side's panels closer, to recreate an even distance)
Can you think of any case examples, where you did feel a half foot off center was worthwhile? If it would require too much typing, don't bother.

Originally Posted by bpape

Remember that seating location, monitor location in relation to the wall behind them and the wall beside them, and the way you treat directly behind the monitors are all usable items in tuning your bass response.

You're mentioning these points, as the practical considerations to explore first, before someone would ever bother with off center modal combat madness?

I'm not sure what is happening with the pic, as it was working yesterday.
Since the post is blank at the moment, I'd assume the file host must be down.
If it still matters to anyone, speak up.

MH

[bpape]

I guess my point was that it wasn't only seating position that can impact bass response smoothness - that there are other things that can be useful.

As for the assymetry, I wasn't saying move the panels closer. I was saying that the points may shift enough to cause the panels to not be directly across from each other from one side wall to the other - or did I misunderstand what you were asking?

Bryan

[MaDHaTTeR]

No, that was it.

Thanks for the information.