Does the first reflection point actually matter??


Hello my friends,

So please read the whole post before commenting. The question is nuanced.

First, as you probably know I’m a huge fan of the well treated room, and a fan boy of GIK acoustics as a result, so what I am _not_ arguing is against proper room treatment. I remember many years ago, perhaps in Audio magazine (dating myself?) the concept of treating the first reflection points came up, and it seems really logical, and quickly adopted. Mirrors, flashlights and lasers and paying the neighbor’s kid (because we don’t have real friends) to come and hold them while marking the wall became common.

However!! In my experience, I have not actually been able to tell the difference between panels on and off that first reflection point. Of course, I can hear the difference between panels and not, but after all these years, I want to ask if any of you personally know that the first reflection point really matters more than other similar locations. Were we scammed? By knowing I mean, did you experiment? Did you find it the night and day difference that was uttered, or was it a subtle thing, and if those panels were moved 6" off, would you hear it?


Best,


Erik
erik_squires
By your question you seem to assume that 1st reflection points are correctly treated by using panels etc. I suspect that there are other and, perhaps, better ways and this is often just a band aid approach which facilitates placing the speakers too close to a wall. 

It seems that many folks want the appearance of a super wide soundstage which is best effected by utilizing the first reflection point. When they do this, IMHO, the combination of direct and 1st point reflections contribute substantially to a reduction in clarity. And a reduction in depth of image as well. If you don't hear this, with or without panels, as you seem not to do, then perhaps you are listening for the wrong thing, i.e. 'brightness'. 

Personally I find drilling down correct speaker placement and appropriate toe in are a far better solution to the problem of side wall reflections than just putting a foam panel on the wall, etc. 

FWIW.

 
Just do what sounds best to you and stop worrying all the time Erik.

You cant make a bad speaker sing. I suspect its your speakers that are to blame for the poor sound quality.

Why dont you reveal to us what aspect of the sound you are not happy with?
By your question you seem to assume that 1st reflection points are correctly treated by using panels etc.

Oh, no, I'm questioning the ENTIRE canon which believes 1st reflection points even matter. In my experience, these points are not actually more important than other nearby points.   That is, treating the room well matters, and treating the 1st point does not.
Put this another way, if your room is well treated, and speakers well placed, then you can move off axis and you won’t hear a dramatic shift in clarity when those panels are no longer in a mirror’s line of sight of the speaker.

If that statement is true (and for me it has been) then the 1st reflection points are myths.




Listening in a somewhat near field fashion, I just concentrate on speaker placement and toe in. I’ll leave room treatment for another day if I ever get a dedicated, and proper sized room.

The sound is great and I’ve had two people who’s ears I trust over for some listening (Tony Minasian of Tonian Labs and Elliot Midwood of Acoustic Image) and they said it’s just fine the way it is.

Minor adjustments can and should be made, like when I mounted the TV to the wall. Doing that increased info in the center stage I didn’t know was missing. I knew it was a bit smeared but not MIA. The TV was originally about mid way between the speakers depth (front to back) when on the media stand and now is about 5" behind the rear most part of it and it made a big difference. Much more coherent.

All the best,
Nonoise
@kenjit

You make 4 suppositions which are not in evidence, so as usual I am ignoring you. 

E
@erik_squires  I am genuinely interested to know your opinion on how your system sounds and what you think needs to be improved. I have asked you this before. Why are you refusing to answer this simple question?
@kenjit,

1 - The proper way to discuss this is not to hijack a poster’s threads with questions and false innuendo that are not relevant to the discussion.

2 - I don’t owe you a discussion.

Best,


Erik
Regarding experimentation, when setting up my current system location I tried GIK 244 panels with scatter plates, GIK Polyfuser absorber/diffusers and them GIK 2A Alpha Pro panels in the first reflection points and the differences were apparent in each case. Night and day differences, no. But it wasn't hard to make a decision about which design sounded better either. I suspect if the basics of speaker positioning and suitability of the speaker to the room size are correct, it's unrealistic to expect such dramatic improvement from panels in the first reflection points. FWIW, when initiating a discussion about room acoustics and you have an experience that goes contrary to generally held assumptions, it might contribute to meaningful discussion to have your system & room setup posted so those you solicit opinions from would know where you're coming from. 
1st reflection points typically do matter most meaning more than 2nd, 3rd etc. Reason being that is where the absorbing effect of treatments will typically be greatest FBOFW.

The only treatments I use with my Ohm Walsh speaker setup are 24” x 24” auralex pads on walls at the first reflection points to my primary listening locations. These are pseudo-Omni ie very wide dispersion speakers that deliver a large sweet zone not just a single spot.

These are far enough away to probably not be a problem in regards to early reflections which is always bad. More of an insurance policy for that.

My assessment is they did help solidify and focus the soundstage and imaging. Which is what I was shooting for, so they remain there. Nothing to do with tonality of the sound. I do other things in there for that as needed.
depends on toe in and size of listening triangle relative to room boundaries, and in the case of this particular query, the side walls

if speakers firing straight ahead, and speakers have a wide dispersion pattern, the first reflection is key to manage
Hey @mapman

I'm curiuos if you have attempted to move those absorbers just off the mirror point?  Leave them nearby, just not exactly where they were.

Is the difference stark??


Hi @photon,

Well, I didn’t have just one system in one room. I’ve had several systems across multiple apartments.

Never a dedicated, music only room. I’ve had Monitor Audio, Focal, and now my own custom speakers. In placing the GIK Acoustic panels I never had a big "Oh wow" moment with 1st reflection points.

What mattered more, MUCH more, was having enough room treatment.

Best,

E
No need to do that with the Omni Ohms. I can just listen from other spots nearby where the pads are not at first reflection and compare again. Will do that when I get a chance and report back.
Thanks @mapman!!

So the other area which to me is more important is the floor between and behind the speakers.   It seems that treble harshness always lives there.

Definitely not first reflection points.

Best,

Erik
Post removed 
@erik_squires, It has been my experience that treating the first reflection points from the sidewalls in a narrow (14') room makes an enormous difference in imaging.   But I didn't get this using "normal" absorbing panels such as GIK monster traps.  What actually worked really well was a pair of 5' tall CD racks, positioned so that the front edge of the rack is angled out from the wall.  The front edge of the rack is positioned slightly to the rear of the first reflection point.  Apparently, the front edge of the racks are reflecting the higher frequencies from the tweeter and midrange back towards the front of the room.  Thus, reflected frequencies higher than 1500 Hz are blocked from a direct path to the listening position.  They are either directed behind the rack or directed back to the front of the room, thus delaying their arrival at the listening position enough that they do not compromise imaging.  

When the CD racks are removed from the room and I attempt to treat that same sidewall area with GIK products, the image collapses.  If I move the speakers enough to change the sidewall first reflection point, the image collapses unless the CD racks are removed a similar amount.  I've also noticed that depth and width of image is somewhat eroded by using GIK 242 or 244 type panels on the side walls forward of the CD racks.    

Note that this is not another ill advised attempt to use a partially filled CD rack as some sort of diffusor. 

My son did something similar in his room using bookcases, and he reported a huge improvement in imaging. 

Folks who have wider rooms will probably benefit less than those of use who listen in narrow rooms. 
BTW Eric, you seem to only be concerned with 1st reflections off the outside side wall. Don’t forget the effect of 1st reflections off the back wall, floor and ceiling. All important I think. Also consider the propriety of using the LE/DE methodology in setting up your room. When using box speakers I’ve always found a LE/DE set up (or something close to) best.

IMHO, this subject is almost as complex as rocket science due to the fact that the the results of set up and room treatments, most all of the sound folks hear is subjectively judged. Not a bad thing in itself but due to divergent expectations hardly a scientific approach (if one could even be heard). FWIW, I find it interesting reading recommendations for room corrections. Especially corner traps to improve low bass. Folks should look at an anechoic room and see what is really involved in setting up control of bass waves. Makes one wonder about ’bass traps’ typically recommended.

But to answer your original question, Yes 1st reflection points do matter and how you deal with them (not ’treat’ them) is very important if your goal is to obtain clarity and well developed 3 dimensional imaging. IMHO anyway.

YEs, the goal of treating 1st reflection points is typically to safeguard against early reflections which smear the soundstage and negatively impact imaging but can also be used to change teh balance of direct to reflected sound which directly affects soundstage and imaging.

This brings up a great topic, diffusion is better for imaging than absorption. :) 


Two different but similar things. YMMV with each.  Diffusion would serve no purpose with omnis like Ohms.   More directional designs, like my Kef ls50s in the next room, yes.
Post removed 
In my room which is practically square,a 2' x4' GIK panel on the ceiling has a positive effect.It works the same if it's placed on the floor opposite of it's ceiling position.Shelving and furniture seem to have a better effect breaking up sidewall reflections like brownsfan mentioned.
Eric, Thanks for posting an interesting question. In my case, with dipole planars, the first reflection point is the back wall. I do not have any treatments on what would be considered a first reflection point typically for a directional speaker. Following to see if others with planars have experimented in this regard.
phcollie reminded me I do have adjustable vertical blinds behind the speakers at first reflection points on rear wall and those also have effects on soundstage and imaging depending on how I set them. As does opening or closing the sliding glass door. The plot thickens.......

Are you going to make me test out all the possible configurations now? I can tell you it all sounds great. Opening the sliding glass door tends to have a negative effect in the center of the soundstage.

The Ohms have some very unique and interesting characteristics when it comes to soundstage and imaging in that L shaped room I bought them for in particular that I have expounded on several times in other threads so no need to complicate things even further here though first reflection points and being omnis are a big part of it.
Yes I have. Quads and Accustats. Both ultimately set up about 5 ft from the back wall and I used diffusion on the back wall mostly between the speakers. No side wall considerations were necessary due to the limited horizontal dispersion patterns of both speakers.
Eric:

Try the "Circling Tones Test" with and without the first reflection side wall panels:

https://www.yarlungrecords.com/sonorus/

In my room, the sound is a full 180 degrees with the GIK panels and a little less without. Noticeable.
I have Maggie's 8 feet apart, 4 feet out from the wall and 11 feet from my listening position. I have my second set of tower speakers up against the wall behind my Maggie's  to help with rear reflections.  My big concern, and I'm stuck with it, is that my couch is up against the wall. Because the audio room is above my three car garage I have no issue with side wall reflections and l think the sloped ceiling also helps. I must say I'm very hapoy with the soundstage, inner detail and dynamics. If you would like to see (and hear) my room configuration just look up, magnepan .7's playing SRV  on Youtube
Okay now you are questioning the holy grail. 1st reflection points.
I built 12each of  2' x 4' x 2" Owens Corning 703 absorbing panels.

In a room of 15' x 18' open to other rooms I deployed 2 panels on the ceiling, 2 behind the speakers, 2 for early reflections and 2 behind the listeners. Floor is carpeted.

The difference was so profound I nearly cried.

Now your post makes me question which panels are the most critical.
My sound was harsh and staging was poor. GIK 244 full range absorbers at my first reflection points made such a large improvement I could not believe my ears. I then bought numerous diffusers for the rear wall and directly to my left and right.  More absorbers are in the works. The first reflection points are key. 
Hi Erik,

So I have also had problems believing in the first reflection point.  Whatever I tried seemed to make no difference at all. I've tried many times in many different ways but mostly using thick fabric panels.

For years I've always had a nice thick rug in front of the speakers and a diffuser panel on the wall behind the speakers with a panel on either side.
The speakers were usually along the long wall of my rooms...as they were also part of the entertainment system (TV).

In my last house (the one before my current house), the chosen room would not support the diffuser panel because there was a pony wall (low wall) behind it and I decided to use the rug elsewhere instead.  The left speaker (Salk Songtower) was 10" from the pony wall and about 20" from the left wall.  The right speaker was also 10" from the back wall but there was no right wall.  The right wall didn't start until about 9' into the space.

Clearly not an ideal setup...but for the first time I had a dedicated room for the audio with the speakers on the short wall of a bigger room.

Sound was OK...not great...but sounded good enough for me.

My girlfriend at the time suggest I move the stack of records (3 stacks high) from the right wall (near the middle of the space) to the left wall nearer the audio rack.  Only problem was that it was very close to the left speaker (way too near the speaker to be a first reflection point) but I decided it made sense form a practical POV.  

That one change fueled my obsession with the room acoustics. Even though the right speaker had no wall the stacks of vinyl refocused the sound on the left speaker to a point that everything was more coherent...locked in.  It's as if the sound had more clarity, focus and precision.  BIG, HUGE improvement in creating a 'reality' to the music if that makes sense. 

Over the next 6 months the tweaks resulted in the 180 degree change to the other short wall, nothing between the speakers but a rug and the audio rack along the right wall. I finally understood what imaging/soundstage was about.

You've got to try everything...every position sounds different.  I tried so many things but now have a sense of how a rooms work acoustically. 
That experience has helped me set up my current home.  But it will never be like that room.  That room was perfect.  BTW, it also had an acoustic ceiling...not the soft kind.  It was the early concrete acoustic ceiling which has no asbestos.  Acoustic ceilings get a bad rap.  They're the best thing going.




The first reflection point results from a basic flaw in most speaker designs: flat baffles with front firing speakers. The real solution to your problem are omnidirectional speakers which much more closely emulate the natural propagation of sound and obviously obviate the whole topic.
@erik_squires 

So the other area which to me is more important is the floor between and behind the speakers.   It seems that treble harshness always lives there.

Definitely not first reflection points.

Can it be that the floor is closer to your tweeter than your sidewalls?
(I hope your ceiling is also further away from your tweeter than your floor) 😉

That may be the reason why you got that conclusion/s..

(The first reflection points are lik said on all the different types of room boundaries. The character and why it is called the "first" is it the "first" time the direct sound bouncing against a boundary. That means that each time a bounce is occurring some energy is lost into that boundary it reflects on. So the first reflection is the strongest one or let say it has the most energy left in it. If we look at if you play against the long wall and only look at the side wall reflections then the sidewall reflections is so far away and the sound need to travel so far that it will loose energy just because of that and as we also know is if the reflected sound is arriving to the listening position more than 5ms delayed than the ear brain can distinguish between what is reflected and what is the direct sound but if the side walls were closer/less than < 5ms than our brains can not separate what is direct or reflected sound.
As we see the replies in this thread is mixed because our experiences is with different distances to the side walls and nobody is specifying what distance to the side walls they have when they tell us their experience..)
My speakers sound just fine, at least to me in my room. No acoustic treatments whatsoever. The room is furnished with a mix or balance of reflective and absorbing materials. I just turn the system on and enjoy my music. I'm not fussing over this stuff, as it makes the hobby unenjoyable to me. Besides, all these things stuck up on the wall are ugly. I'd rather accomplish basically the same thing with a balanced room via its contents or furnishings. Jmo
@gs5556 

Thank you for the circling tones test link.  Freaked me out...I could swear there was a speaker directly to my right and left.  Very cool holographic test.  
YES i use STILLPOINTS APATURE panels they make substantial improvement in imaging,bass and sound stage.I also use 2 more as well these are the best by far.
Regarding the need for treatment at reflexion points I believe there are many factors at play.

Some that come to mind at this moment:
type of speaker
size and dimensions of room
orientation of speakers in room
absorption vs diffusion
near field listening (degree of)
placement of funiture
one's sonic preferences

Now your post makes me question which panels are the most critical.



And that’s all I’m trying to do. Imagine you place 8 vertical panels around the room, with 4 of them at reflection points. If you then rotate them all, say 15 degrees from the listener's line of site, so they are no longer exactly on the mirror line, does it do anything all that critical? I do not think so.

The most important part is getting to critical mass in absorption, and adding diffusion in the right areas. The laser-line, first reflection points, in my mind, have never born fruit.
I gave GIK and Acoustical Surfaces a dozen pics of my room for recommendations and they each came up with completely contradictory suggestions. GiK was all about absorbers covering as much of the surface area of the walls and ceilings as possible while AS took a more balanced approach but wanted me to use diffusers for first reflection point and in corners which I thought was odd.

All I got was more confused so im going to buy software to analyze my room first so I dont waste money and make mistakes. Deadening the room can just as easily kill dynamics.

As an aside, i did almost a dozen speaker demos the past month and all dealers had diffusion on the walls between the speakers. GIK said you want absorption between so again conflicting messages.
@aj523

To my experience, as others here have noted, diffusion at the 1st reflection points are a better idea.  They enhance imaging.

Best,

E
Does the first reflection point really matter?

For my 2 cents, how sound reproduction interacts with the room is a Very complex subject.

The original problem for the writers back in the day? Sure, they could all see how important it was, but it all covers so much territory. How do you write about such a varied topic every time out without oversimplifying it to the point of shortchanging it? You don't...because you can't. So, the next best thing is to try to simplify it for 'average' or 'typical' situ's. So everyone ended up with their own 'rules' designed to help keep advice simple...only for every rule there are invariably (too) many exceptions.

Think of it as your 'system' vs the 'room'. Every system has its own ability (or not so much) to project into the room. The total ability of which is made up of the sum of each individual component, wiring, power treatments, EQ, etc. Not only is each system's range and envelope of sound unique, but change just one setting or component and that projection into the room changes accordingly. And for every change in sound projection behavior, there is potentially a different room treatment solution, even if it is only based on using the same room treatment components, just rearranged differently in the room in relation to the stereo...or in relation to the lp. Even that doesn't begin to cover it all.

But, in the case of the first reflection point (or perhaps any other), real-world end results are so often all over the map, from crucially important to nearly non-existent. Because there simply Are no formulas for it that can take all the variations of the system into account, even with a microphone. In the end, I'm tempted to say that the best fine tuning is always going to come from first-hand, empirical experimentation, regardless of how many rules, good or otherwise, may be available, or that can be relied upon to get us 'in the ballpark' first.
In my experience all first reflection points matter, side walls, floor, ceiling, front and back wall, 12 points in all from my calculation. A 40% / 60% ratio absorption / diffusion works well for me. I followed GIK's advice and started with absorption at the 4 side wall points (considered rightly or not the absolute first reflection points by most). To me, in my room, the floor between the speakers and I is the true first reflection point. They all matter IMO.
Well said, @ivan_nosnibor.
Erik,

“The most important part is getting to critical mass in absorption, and adding diffusion in the right areas. - Agreed.

“The laser-line, first reflection points, in my mind, have never born fruit”
Not entirely true. Think of laser line as your reference point. Once you mount the panels using the reference point (first reflection) and moving or rotating them say 15 degrees from the listener’s line of site, so they are no longer exactly on the mirror may result in slight shift in the imaging, IMHO.

Now if you want to cover the entire wall with absorbers / diffusers then taking a systematic approach of targeting a first reflection point is pretty much a mute point :-)
Erik - I've been following Dennis Foley, Acoustic Fields, youtube video series, https://www.youtube.com/watch?v=uuSgzTk0lIE. He will perform a free initial consultation/analysis of your room.  For the DIY guy, he sells a software suite package for building bass traps and diffusers.  I cant speak for his work as I'm just kicking the tires on room improvements at the moment, but he seems to understand acoustics and does a great job explaining room issues.  Best of luck!
+1 Dennis Foley, he's the real deal.
You bet it does.

Listen to the difference.
Worked wonders in my room!
Erik, I use GIK panels as well. I have a small room in which I listen near field. The panels are essential, but I moved the two on the sides about 1-2 feet toward the back leaving the first reflection point exposed. What a difference. The front and rear panels needed adjusting as well, but the two on the sides made the most profound difference.

I think the FRP is a good place to start and adjust from there.

Rollin