Does the first reflection point actually matter??

Let me alter my thesis, because the original was so hard to transmit, even by those who really know their stuff. In fact let me reword it ENTIRELY.


"In a modest, average home listening environment, you can’t do much for the acoustics with just 4 panels, no matter how ideally placed they are."
There.

And that is what I was sold, long ago, as something useful. Get 4 panels, put them on the reflection points and imaging and detail will get better. I’ve done this. It does not. You can’t do anything with these 4 by themselves.

Part II:

" The overall decay rate of the energy in the room will probably so obscure the original and early reflected signals requiring a minimum critical mass of room treatment, or minimum sound field quality that must be achieved before those original 4 panels mean anything. Control the reverberation time first, and with 4 panels you are barely getting started."


Part III:

"Once the overall sound field is treated, the _exact_ placement of the original 4 panels. becomes moot. You can move around the room and everything sounds good, no matter where you are, and no matter if the current reflection points (which change based on your position) are covered or not.

Part IV:

"While the overall idea of our ears seeing / hearing mid-treble frequencies as light beams is attractive, it is my experience that even then we hear not photonically but statistically. Covering up that magic reflection point to 1 ideal seated location is a trivial if not imperceptible change. Treat early reflections statistically, not precisely. "
Of course, much here in part IV can probably be informed by Head Related Transfer Function research, which I have not looked into.

I'm clearly not saying not to treat the wall behind the speakers or to the sides, or the floor or ceiling.  I'm saying that the original messaging, that there are 4 magical places you must put panels on and that alone will provide noticeable improvement oversells the benefits.


Best,
E

"In a modest, average home listening environment, you can’t do much for the acoustics with just 4 panels, no matter how ideally placed they are."

why 4 panels? 2 for each side walls, one for behind the listening position, 1 for ceiling (but really a cloud needs to be at least 2-3 panel wide) and 1 for the floor= minimum of 5.
not sure who told you 4 (I guess some dont treat the floor)

the definition of FRZ is at least covering the 5 early reflection points. so only 4 panel is not reallya chieving a free-reflective zone (FRZ)

" Part II:
The overall decay rate of the energy in the room will probably so obscure the original and early reflected signals requiring a minimum critical mass of room treatment, or minimum sound field quality that must be achieved before those original 4 panels mean anything. Control the reverberation time first, and with 4 panels you are barely getting started."

this is quite confusing. early reflections are well established to be detrimental to SQ. secondary reflections (which you refer here as "sound field") have been well established to actually be desired for good sound. hence some studio room desing with trying to actually reflect the secondary reflections to the listening position.

" Part III:

"Once the overall sound field is treated, the _exact_ placement of the original 4 panels. becomes moot. You can move around the room and everything sounds good, no matter where you are, and no matter if the current reflection points (which change based on your position) are covered or not."

the definition of a early reflection must be located at one spot. its that one spot that determine the early reflection points. if you want to cover early reflections with multiple listening position that are far apart from each other, this is a almost impossible (unless you have every listening position on the same couch for example, there youd just have to have wider panels to englobe every different listening position) task as each different listening position will have its own different early reflection.

" Part IV:

"While the overall idea of our ears seeing / hearing mid-treble frequencies as light beams is attractive, it is my experience that even then we hear not photonically but statistically. Covering up that magic reflection point to 1 ideal seated location is a trivial if not imperceptible change. Treat early reflections statistically, not precisely. "

what a bunch of baloney. early reflection points are physics. its not magic, they are a fixed point related to the listening position.

about the behind the speakers panels. by definition, there’s no early reflections coming off behind the speakers (unless your speakers are toed in 45 degree). those "behind the speaker reflections" are called SBIR and its a entire different discussion.

just to add a bit, early reflections are those over the 300hz barrier. bass frequencies being omnidirectional are not related to early reflections. for bass, you need deep bass traps, as deep as possible.

sorry if yesterday ive acted a bit rude, in retrospect it was. sorry

What a bunch of baloney.

Wait a minute. Wait just a doggone minute. The man clearly said:
"it is my experience that even then we hear not photonically but statistically." You call that baloney? Word salad, I say!

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Another observation is that low bass is radiating omnidirectional so those low frequencies are radiated behind the speakers. I see great corner bass absorbers. But there is also thin foam that will not help against that the bass is reflecting from those surfaces. Instead those foam will only take hi frequency reflections and also contribute towards "over-damped" feeling. Maybe remove or replace with thicker absorbers. 

I found some mid/high absorption behind the speakers to be beneficial, the corrugated foam is there for that. As you say, it won't provide any absorption at low frequencies. It's a balancing act though, too much absorption definitely kills the sound. I've tried diffusers in place of the absorbers in that position, but I prefer the mix of both.

When my house was built I had some input into the room dimensions, which follow one of Sepmeyers ratios to avoid stacking of bass modes. This seems to have alleviated the need for heavy bass trapping, I certainly don't have any obvious bass drone or boom.
It probably also helps that my ATC speakers are blessedly free of bass bloat. Though quite extended, the active SCM100 maintains iron fist control of the bass for a taut linear sound. 

Is those cool white 3d diffusers the "styrofoam" or other material? 

They are Vicoustic DC2 styrofoam diffusers. Lightweight and easy to hang with removable 3M velcro tabs.  
The diffusers can be applied more liberally than absorbers before detrimental effects on balance - but everything has its limit, so best to add any treatment in steps rather than slathering it everywhere.