Fixing asymmetric room with absorption panels?

[o2so]

In my night time configuration, which is just how the room looks like normally, the system and listening position are shifted to the left of the room. I thought I'd try and partially fix the asymmetry with two large panels.
Just testing it out now. The subjective impression is that panels take a bit of sparkle away but add texture to the highs and more stability to the sound stage.
Will measure in the next few days.
What do you guys think? Worth the hassle of putting the panels in place each time?

With:

Without:

 

[thewas]

In my limited past experience side wall absorbers can quite improve the situation at asymmetric locations, looking forward to your findings.
Also out of personal curiosity, is there a special reason you use your LS50 in "landscape orientation"?

 

[A Surfer]

Gorgeous room by the way. Is that a vintage Danish Teak piece under the turntable?

 

[Daverz]

My idea to even up the reflections was to put casters on some diffusors so they can be moved into locations that even up the soundstage while listening. But I've never tried this. Diffusors tend to be more expensive than absorption panels.

And, of course, this won't matter as much as removing the spring covers from your Gyro.

I would suggest that you probably only need to place the panels at reflection points, and you can just lean them vertically against the reflection points on the fireplace and opposite wall. Easier than using the chairs.

 

[o2so]

Gorgeous room by the way. Is that a vintage Danish Teak piece under the turntable?

A sophisticated Ikea piece indeed

 

[o2so]

In my limited past experience side wall absorbers can quite improve the situation at asymmetric locations, looking forward to your findings.
Also out of personal curiosity, is there a special reason you use your LS50 in "landscape orientation"?

Because dispersion is the same but I think they look better in landscape on those stands

 

[o2so]

First batch of measurements done late last night so at a low-ish volume show puzzling results. The panel to the left, over the fire place, does not seem to do much on first reflections from the left speaker. In fact, it seems to make things slightly worse! On the other hand, the panel on the right seems to work much better and completely removes the spike at 6.5ms.
Any possible explanations? These are high density 6cm thick foam panels. Note that the right panel was angled slightly upwards while the left one was perpendicular to the ground. Not sure if this could be the reason?

 

[Lorenzo74]

Because dispersion is the same but I think they look better in landscape on those stands

Dispersion is not the same since baffle has different width!
if you place them rotated 90degree you will have wider vertical dispersion that affect imaging since damage impulse response by increasing the floor and ceiling early reflection so vanishing any improvment you’ll get by reducing lateral early reflections.
remember our brain doesn’t like reflections in the first 10-20ms at highr than -20db vs direct sound especially from floor or front wall or ceiling (on axis) while forgive lateral impulse.
fortunatly we have one ASR member @jackocleebrown very well informed about your speaker that might spend some time and help kef customer in proper speaker placement.
let’s cross fingers and wait...
my best

 

[Daverz]

First batch of measurements done late last night so at a low-ish volume show puzzling results. The panel to the left, over the fire place, does not seem to do much on first reflections from the left speaker.

Try placing the panel vertically.

 

[Lorenzo74]

First batch of measurements done late last night so at a low-ish volume show puzzling results. The panel to the left, over the fire place, does not seem to do much on first reflections from the left speaker. In fact, it seems to make things slightly worse! On the other hand, the panel on the right seems to work much better and completely removes the spike at 6.5ms.
Any possible explanations? These are high density 6cm thick foam panels. Note that the right panel was angled slightly upwards while the left one was perpendicular to the ground. Not sure if this could be the reason?

View attachment 107202

View attachment 107201
View attachment 107203
View attachment 107204

may I suggest to change vertical axis from dbfs to linear? Then overlap right with and without panel. You defintely will see around 2-3 ms the reflection attenuated when panel is there and the same reflection much after in time thanks to far sidewall.. in principle better far wall than suboptimal near absorption. Of course comparing to left side you can see how the configuration with two panel makes the lateral arrival at same time after direct sound.
i would try to place permanently lateral absorbers only on 1st reflection point (I did also on ceiling) . try using mirror.
best

 

[thewas]

First batch of measurements done late last night so at a low-ish volume show puzzling results. The panel to the left, over the fire place, does not seem to do much on first reflections from the left speaker. In fact, it seems to make things slightly worse!

Often such high density absorbers don't work as greatly at higher frequencies, especially when the angle of incidence is low, see also this thread which dealt with a similar problem:
https://www.audiosciencereview.com/...eft-biased-soundstage-early-reflection.19236/

Dispersion is not the same since baffle has different width!

Mind you that in these dimensions baffle step is around 500 Hz (where the directivity is very wide) and doesn't affect much the dominating dispersion above which is dominated by the midwoofer and tweeter waveguide.

 

[Lorenzo74]

Mind you that in these dimensions baffle step is around 500 Hz (where the directivity is very wide) and doesn't affect much the dominating dispersion above which is dominated by the midwoofer and tweeter waveguide.

mmm... respectfully disagree! More than 3db from 500Hz upward.
here you go
horizontal
https://www.princeton.edu/3D3A/Directivity/KEF LS50/index_H.html
vertical
https://www.princeton.edu/3D3A/Directivity/KEF LS50/index_V.html
best listening

 

[o2so]

Dispersion is not the same since baffle has different width!
if you place them rotated 90degree you will have wider vertical dispersion that affect imaging since damage impulse response by increasing the floor and ceiling early reflection so vanishing any improvment you’ll get by reducing lateral early reflections.
remember our brain doesn’t like reflections in the first 10-20ms at highr than -20db vs direct sound especially from floor or front wall or ceiling (on axis) while forgive lateral impulse.
fortunatly we have one ASR member @jackocleebrown very well informed about your speaker that might spend some time and help kef customer in proper speaker placement.
let’s cross fingers and wait...
my best

I am confused. Vertical and horizontal dispersion really look the same to me. See here:

https://thenextweb.com/plugged/2020...grades-an-audiophile-fave-to-near-perfection/

 

[thewas]

mmm... respectfully disagree! More than 3db from 500Hz upward.
here you go
horizontal
https://www.princeton.edu/3D3A/Directivity/KEF LS50/index_H.html
vertical
https://www.princeton.edu/3D3A/Directivity/KEF LS50/index_V.html
best listening

How do you define the 3dB?
I see for the most dominating (thus smaller angles) mainly significant differences above 10 kHz,
for example 30°

and 60°

and am quite positive that the horizontal and vertical directivity indices will differ less than 1dB except maybe at very high frequencies.

 

[o2so]

Of course comparing to left side you can see how the configuration with two panel makes the lateral arrival at same time after direct sound.

Where do I see this in my charts? Sorry, first time I measure reflections.

 

[thewas]

and am quite positive that the horizontal and vertical directivity indices will differ less than 1dB except maybe at very high frequencies.

Which seems also to be confirmed here https://www.princeton.edu/3D3A/Directivity/KEF LS50/index_DI.html

 

[andreasmaaan]

Any possible explanations?

What are the distances from:

• mic to L speaker
• L wall to L speaker
• mic to L wall
• mic to R speaker
• R wall to R speaker
• mic to R wall

?

 

[o2so]

Try placing the panel vertically.

why do you think this would make things better?

 

[o2so]

Often such high density absorbers don't work as greatly at higher frequencies, especially when the angle of incidence is low, see also this thread which dealt with a similar problem:
https://www.audiosciencereview.com/...eft-biased-soundstage-early-reflection.19236/

I think what might be happening is that without panel the first reflection on the left lands right on the corner of the fireplace, or even before it, then bounces around in the front left corner of the room and may not even ever get to mic. Whereas with the panel in place, that corner is covered by the panel and this sends a reflection (though attenuated by the panel I would hope) to the mic (see small peak just below 2ms which is absent in the no panel configuration). I will test this theory.

 

[Daverz]

why do you think this would make things better?

Covers more of the mantlepiece.