Best Acoustic Products for First Reflection Points

853guy · Oct 21, 2017

Ron Resnick said:
Thank you, 853guy!

I am not clear what you are intending in your last paragraph. Are you suggesting that it was the mix of absorption and diffusion that achieved impressive soundstaging/imaging, but that that same mix diminished center fill and dynamics, and that that audiophile would have achieved a better balance of soundstaging/imaging and dynamics if he had selected absorption or diffusion at the first reflection points (rather than a mix of absorption and diffusion)?

Hi Ron,

Sorry, my bad - I should have been more clear.

I mean to say that irrespective of whether absorption or diffusion, or indeed, a combination of both was used to treat the first reflection point, those particular rooms achieved their result (soundstaging/imaging) at the expense of other musically meaningful and sonic priorities. In other words, in those specific situations, for those particular rooms, with those particular speakers, the result was a net loss overall, despite gains in one or more areas.

The issue was not that they attempted to deal with the first reflection point, it was not understanding how in prioritising the first reflection point they affected other aspects of reproduction because the solution was targeted toward a single problem in isolation, rather than the problem(s) as contextualised within the whole.

Diffusion and/or absorption in-and-of-themselves are not solutions to dealing with the first reflection point - whether diffusion and/or absorption is the solution again comes back to the dispersion characteristics of the speaker and its energy propagation, considered and understood within the greater whole of how the room deals with that energy, and what level of priority treatment of the first reflection point should receive relative to other concerns. Often, the only way to know is after the fact, as Mike’s testimony bears out. Theory is fine, and for sure, should never be discounted, but it’s no substitute for real-world blood, sweat and tears experimentation once the system is in situ (unfortunately).

Aside from the recommendation to try the SMT wings, the other would be to visit those who already have Pendragons, and hear how their rooms deal with the energy propagation specific and particular to the Pendragon, at real-world levels with real music (preferably yours).

Best!

853guy

caliaripaolo · Oct 21, 2017

Ron Resnick said:
caliaripaolo, In my particular set-up I place no treatment behind the speakers. I want a clean, unadulterated rear wave bouncing off the front wall. This is one reason I am inclined to use absorption at the first reflection points rather than diffusion -- I want an unadulterated reflected back wave so I want to make sure no first reflection mixes with that back wave
?

Ron,
I started my acoustic journey by treating the first reflection points using Realtrap absorber panel for mid-high frequencies.
But the sound was dead.

Please see and listen the last part of the here after video (when the guy play the guitar),

https://youtu.be/BXq54Q63cyE

MtnHam · Oct 21, 2017

Anyone have experience with Stillpoint Apertures?

http://www.stillpoints.us/index.php...ture_Cherry_showing_Stillpoints_Wood_Branding

Ron Resnick · Oct 21, 2017

caliaripaolo said:
Ron,
I started my acoustic journey by treating the first reflection points using Realtrap absorber panel for mid-high frequencies.
But the sound was dead.

Please see and listen the last part of the here after video (when the guy play the guitar),

https://youtu.be/BXq54Q63cyE

That was a very interesting and persuasive video.

Thank you!

microstrip · Oct 21, 2017

Using inappropriate materials can ruin a listening room.

F. Toole quotes :

"In some ways, our problems with rooms, especially small rooms, began when
we started to make measurements. Our eyes were offended by things seen in
the measurements, but our ears and brain heard nothing wrong with the audible
reality."

"All of this is especially relevant in room acoustics because acoustical materials,
absorbers and diffusers, routinely modify the spectra of reflected sounds.
Whenever the direct and reflected sounds have different spectra the simple
broadband ETC or impulse responses are not trustworthy indicators of audible
effects."

Ron Resnick · Oct 21, 2017

microstrip said:
. . . Mark Levinson (and now Audio Research in their listening rooms) used to put the Abfusors in the center of the front wall and the Difractals/QRD 734's in the lateral positions of the wall. Keith Yates "A matter of diffusion" is always a mandatory and great reading about these subjects : http://keithyates.com/a-matter-of-diffusion/

Thank you for this Keith Yates article, Francisco. You are correct -- it is absolutely essential reading!

Keith's listening room experiences described in the article leave him arguing for wall-papering all four walls with RPG diffusors.

One slightly puzzling element of the article, however, is that after spending most of the article explaining how great it was to have RPG diffusion on all four sides of the listening room, towards the end of the essay, in the "Recalibrating the Listening Room" section of the article, Keith suddenly recommends absorption at the first reflection points: "At [the first reflection] points attach Sonex . . . or similar [absorption] products." I cannot reconcile this with his broader conclusion in the article.

rockitman · Oct 21, 2017

MtnHam said:
Anyone have experience with Stillpoint Apertures?

http://www.stillpoints.us/index.php...ture_Cherry_showing_Stillpoints_Wood_Branding

Everyone I know who has them, loves them.

NorthStar · Oct 21, 2017

miniguy · Oct 23, 2017

This thread ought to be moved to where it belongs - the Room Acoustics Forum

flyer · Oct 24, 2017

bonzo75 said:
The
They are kept close because the wings are 1.5 to 2 feet deep, so the waves are supposed to be traveling that much and coming out

Allow me a few words, not just on the above statement but some others, just to clarify.

1. The wings are 20 cms deep in construction but what bonzo probably meant is that the sound travels a few feet feet inside the wing, for its timedelay to function.

2. I had the wings already in place when I had my dipole Analysis Audio Omega panels in place, and that worked very well together. By having the diffusion and SMT-effect all around, both on the side and the back of the speakers, makes for a very holographic image AND obtaining excellent focus and timbre.

3. If you don't like the looks of the SMT wings, just put an acoustic transparent cloth in front of them, like both Magico and Wilson did at the Munich High End show in 2017. Some other brands that were using them as well at the show left them mostly uncovered.

4. To a much lesser exotic degree than Mike Lavigne, I too struggled for almost ten years with the acoustics of my small room (22m²). i can write a book about it by now. But if there is one recommendation that I can give, then it is this one: put absorbers, if you really have to (e.g. taming reverb time), only in at the very end of the process, don't have any 'HAVE-TO' in the thinking process. What will absorbers do at the point of first reflection : absorb (unevenly)! In other words, you somehow cancel the polarity response of your speaker and the stage becomes less wide. Now, if you would want to overcome this effect after you put absorbers there, you will increase the volume which in turn will lead to other undesired acoustic effects and then you are off for a merry go round in putting absorbers in till you are deaf or purchased a new pair of amplifiers because the prior ones can't cope with the up to 6-8 dB sound increase required. From my previous 'dead-sounding' room to my current full-SMT one, I had to lower the sound by that much!

5. On the eternal subject of measurements: have you ever tried to compare the measurements of two manufacturers? Until now I haven't found two that can be compared, they all use different protocols. I even wonder if this is not intentional, to avoid plain comparison... Regarding SMT, there is no protocol to measure the effect of the timedelay available, so a scientific measurement would not be able to capture the total combined effect of the wing. This does not mean it cannot be measured but there is no protocol for it and certainly could not be used as a yardstick for the measurement of others.

6. Does this discard any other possible acoustic treatment? Of course not, but the SMT is the only I know that has such great effect whilst sitting at even only 40 cms from it!! For a schroeder panel to do its work properly, you have to keep a distance of at least 4 times the maximum wave length it affects. The picture of the room of Andy Payor here somewhere is a good example where it must have very good effect given the distances, but doubt many people have such room size.

The above is merely my proper experience and recommendation. Hope it helps.

Ron Resnick · Oct 24, 2017

853guy said:
Hi Ron,

Sorry, my bad - I should have been more clear.

I mean to say that irrespective of whether absorption or diffusion, or indeed, a combination of both was used to treat the first reflection point, those particular rooms achieved their result (soundstaging/imaging) at the expense of other musically meaningful and sonic priorities. In other words, in those specific situations, for those particular rooms, with those particular speakers, the result was a net loss overall, despite gains in one or more areas.

The issue was not that they attempted to deal with the first reflection point, it was not understanding how in prioritising the first reflection point they affected other aspects of reproduction because the solution was targeted toward a single problem in isolation, rather than the problem(s) as contextualised within the whole.

Diffusion and/or absorption in-and-of-themselves are not solutions to dealing with the first reflection point - whether diffusion and/or absorption is the solution again comes back to the dispersion characteristics of the speaker and its energy propagation, considered and understood within the greater whole of how the room deals with that energy, and what level of priority treatment of the first reflection point should receive relative to other concerns. Often, the only way to know is after the fact, as Mike’s testimony bears out. Theory is fine, and for sure, should never be discounted, but it’s no substitute for real-world blood, sweat and tears experimentation once the system is in situ (unfortunately).

Aside from the recommendation to try the SMT wings, the other would be to visit those who already have Pendragons, and hear how their rooms deal with the energy propagation specific and particular to the Pendragon, at real-world levels with real music (preferably yours).

Best!

853guy

I understand. I agree, and after reading and processing several posts and advice to the same effect, I have changed my approach in that I will not be going with a fully-built out approach from the get-go. Thank you, 853guy!

Fitzcaraldo215 · Oct 25, 2017

Absorption, diffusion, bass below transition frequencies, mid/treble above transition, side wall first reflections, floor/ceiling first reflections, etc., etc., etc. Room acoustics and treatments via passive or active means is a very, very complex subject. I do not think, amid all the mythology surrounding it, that there are simple answers. And, even "experts" disagree. So, does any "expert" you may retain have the real answers? Some people have been known to have to rip expert treatments out.

Frankly, no so called answers that are truly worthwhile stand a chance of being correct except in our imaginations, unless they are comprehensively measured. Measurements are difficult to interpret, some meaningless, some very meaningful, but all else is total guesswork.

I am not trying to throw a wet blanket on concerns about the room, which can have a really huge impact on the sound. Good speakers alone are just not sufficient, as we know. I am just trying to say that there are no easy answers, including such hackneyed dogmas as "treating the first reflection points". The voice of God himself, embodied in Harry Pearson, told us we must do this, as have many other audio gurus. But, HP or others never had one actual clue about complex room acoustics, which he never understood.

If you really want to get some views with real, honest to gosh expertise on the issue, get Floyd Toole's Sound Reproduction - 3rd Edition. He is a great writer, though some sections may be very highly technical. Bottom line, he says first sidewall reflections and their treatment, absorption vs. diffusion, etc. are vastly overrated, and he has empirical results to back up his opinion. The first reflection points of greatest concern psychoacoustically are the floor and ceiling. Seriously, check this out before wasting a lot of time, energy and money on myths.

Ron Resnick · Oct 25, 2017

flyer said:
Allow me a few words, not just on the above statement but some others, just to clarify.

1. The wings are 20 cms deep in construction but what bonzo probably meant is that the sound travels a few feet feet inside the wing, for its timedelay to function.

2. I had the wings already in place when I had my dipole Analysis Audio Omega panels in place, and that worked very well together. By having the diffusion and SMT-effect all around, both on the side and the back of the speakers, makes for a very holographic image AND obtaining excellent focus and timbre.

3. If you don't like the looks of the SMT wings, just put an acoustic transparent cloth in front of them, like both Magico and Wilson did at the Munich High End show in 2017. Some other brands that were using them as well at the show left them mostly uncovered.

4. To a much lesser exotic degree than Mike Lavigne, I too struggled for almost ten years with the acoustics of my small room (22m²). i can write a book about it by now. But if there is one recommendation that I can give, then it is this one: put absorbers, if you really have to (e.g. taming reverb time), only in at the very end of the process, don't have any 'HAVE-TO' in the thinking process. What will absorbers do at the point of first reflection : absorb (unevenly)! In other words, you somehow cancel the polarity response of your speaker and the stage becomes less wide. Now, if you would want to overcome this effect after you put absorbers there, you will increase the volume which in turn will lead to other undesired acoustic effects and then you are off for a merry go round in putting absorbers in till you are deaf or purchased a new pair of amplifiers because the prior ones can't cope with the up to 6-8 dB sound increase required. From my previous 'dead-sounding' room to my current full-SMT one, I had to lower the sound by that much!

5. On the eternal subject of measurements: have you ever tried to compare the measurements of two manufacturers? Until now I haven't found two that can be compared, they all use different protocols. I even wonder if this is not intentional, to avoid plain comparison... Regarding SMT, there is no protocol to measure the effect of the timedelay available, so a scientific measurement would not be able to capture the total combined effect of the wing. This does not mean it cannot be measured but there is no protocol for it and certainly could not be used as a yardstick for the measurement of others.

6. Does this discard any other possible acoustic treatment? Of course not, but the SMT is the only I know that has such great effect whilst sitting at even only 40 cms from it!! For a schroeder panel to do its work properly, you have to keep a distance of at least 4 times the maximum wave length it affects. The picture of the room of Andy Payor here somewhere is a good example where it must have very good effect given the distances, but doubt many people have such room size.

The above is merely my proper experience and recommendation. Hope it helps.

Thank you very much for this report, flyer.

Do you have carpet and carpet pad underneath on your listening room floor?

Did you add SMT products in stages, or did you have SMT design the whole room and you built it all out from the beginning as prescribed by SMT?

flyer · Oct 25, 2017

Ron Resnick said:
Thank you very much for this report, flyer.

Do you have carpet and carpet pad underneath on your listening room floor?

Did you add SMT products in stages, or did you have SMT design the whole room and you built it all out from the beginning as prescribed by SMT?

I have a thick carpet on the floor but more because I felt I needed it in the previous version of my room. It helps reduce the higher frequency energy and have the lower frequencies come out better.
Since my room is small, the lower frequencies are typically the ones that get hidden most. Given your room dimensions, I would not think this would be of any use. I do think that one tends to treat all 5 surfaces of a room but hardly ever the floor, simply because you want to be able to walk around. Some customers of SMT have done tests, to good effect, by putting some diffusors on the floor as well, don't know if they kept on doing so because aesthetically it is quite mindblowing IMO...

When I had my listening room built, about 12 years ago, I had a 3 cms thick bitumen slab put beneath the concrete slab in my room, to avoid the energy being passed to the rest of the house via the floor. And that certainly helped a lot. I like to think it also helps bringing the noise floor down even further but never have been able to test or ascertain that, but I sure do not regret having done that. I do regret not having the builders excavate 50 cms deeper...

When I still had my previous room installation, I had a number of loose SMT panels in my room with which I could test. Though I already had Schroeder panels in the front and different artefacts all around, the effect of them was so evident that it didn't took long to decide to have my whole room done that way. I then went to Sweden to meet a few of his customer's rooms and got totally hooked...
Next thing was a CAD drawing being made:

It eventually translated to this:

But now it is looks like this because the horns are so big I do not have space for the Varitunes on the back side. The upside is that even such horns function really well in this room giving me a sound I never had before (nor in any other room I visited till now, but I am probably biased in saying this

). Since this picture was taken, I added a few loose V-wings back in: in the front left and right corner and on the first lateral reflection point. I have some modules with specific lengths on order, once I receive them i will take a nice picture of the 'final state'.

You will also notice that I took the carpet away from the front as much as I could, I think that I could do very well without the carpet but hey, it is nice to walk around barefooted.

This is a picture of how the room was installed by 'experts'. i don't think they were, but their tariffs sure were. It didn't took me long to hate it, you can see in the picture I started adding foam pretty fast.

Two years ago I took a six-month course in acoustics because I couldn't find anyone who could help me, except some guys that represent companies that sell absorbers and so-called diffusors in 2 EUR material, selling for 200 for a 60 cms square 'solution'. That is the period during which I came across Matts from SMT and he was the first to give me genuine answers. I don't say there are no other people like him around but I have not come across them though I didn't contact half the world neither!!! There certainly are good other diffusor solutions around as well but they need to be made in the right material, like solid wood, but then the cost (and weight) of these suddenly make the SMT solution very attractive.
I think the diffusors made from EPS, sometimes covered with sprayed paint to give it a more 'solid' look, are mostly worthless having mainly a psychological/visual effect. Again, that is my very personal opinion, but based on a few experiences and my the acoustic knowledge I gathered, but that is a different subject.

Folsom · Oct 26, 2017

Nice post flyer. Its funny you switched to horns that don't give a flip about treatment behind them, because I was thinking I would need windows... Nice to know the company is helpful on top of having a product I can jive with.

I do have to say the white is a visual trip, looks neat.

Ron Resnick · Oct 26, 2017

Thank you very much for all of this detail, flyer!

In the fourth photo are those original diffusers RPGs?

flyer · Oct 26, 2017

Folsom said:
Nice post flyer. Its funny you switched to horns that don't give a flip about treatment behind them, because I was thinking I would need windows...

Don't know exactly how to read your comment Folsom. Why would you need windows when putting horns?
I am of the opinion that whatever (type of) speaker you are putting, a good acoustic treatment will always have a positive effect. The amount of that effect may change between speakers but it will still contribute.

flyer · Oct 26, 2017

Ron Resnick said:
Thank you very much for all of this detail, flyer!

In the fourth photo are those original diffusers RPGs?

You are welcome.

Those are Schroeder panels as quite a few manufacturers make, including RPG.

Folsom · Oct 26, 2017

flyer said:
Don't know exactly how to read your comment Folsom. Why would you need windows when putting horns?
I am of the opinion that whatever (type of) speaker you are putting, a good acoustic treatment will always have a positive effect. The amount of that effect may change between speakers but it will still contribute.

I can enjoy no natural light rooms, but I am sort of like a parakeet; once the natural light is gone I shut down much faster (even at night). It makes some rooms challenging for me. If I am having lots of fun, like at MikeL's, it is easier. And horns have so much CD that rear treatment starts to fold into diminishing returns, so they would allow a wimp like me to have windows. Well, or systems that are dipole if safety glass is used ($$$$$).

What do you have behind your listening chair?

flyer · Oct 26, 2017

Folsom said:
I can enjoy no natural light rooms, but I am sort of like a parakeet; once the natural light is gone I shut down much faster (even at night). It makes some rooms challenging for me. If I am having lots of fun, like at MikeL's, it is easier. And horns have so much CD that rear treatment starts to fold into diminishing returns, so they would allow a wimp like me to have windows. Well, or systems that are dipole if safety glass is used ($$$$$).

What do you have behind your listening chair?

Ah, now understand better, thanks. You are right on diminishing returns, reason why I mentioned 'the amount of effect' being variable. The flower wings on the picture do allow to space the speakers further apart than usual without having a hole in the middle.

My room is in a basement, so no natural light here...

Behind my listening chair? Two acryl s-wings on wheels that stand in front of the door giving access to the room. Panels are at a distance of 30 cms from my couch (50 cms from my ears).

Best Acoustic Products for First Reflection Points

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