What to place in front of center speaker to limit early reflections from furniture?

[gorman]

In a recent discussion (where you can find measurements), it's been pointed out to me that there's early reflections for the center speaker in my setup, likely coming from the furniture piece on which I have placed the R6 Meta speaker.

This is the placement in my room (taken from previous discussion):

A first suggestion was to place the speaker at the front of the shelf. But that, to be honest, would be aesthetically unacceptable for me. It would distract me enormously, making me concentrate all the time on the speaker itself, instead of music and/or video content (I know myself, it happened in a past setup).

As such, I'm asking if there are good suggestions on what kind of material I could use to reduce early refrections, in place of the two black clothes you see in the picture (that are obviously uneffective). One thing I thought of was buying a narrow version of the carpet I have in front, on the floor, and cut it to size. This is the product: https://tapiso.it/product/tappeto-passatoia-essence-shaggy-monocolore-grigio-melange/
As you can see it's 40mm deep but I have no idea if it would work well for this purpose or not (considering the small distance from drivers to reflection point, I suppose much more energy is there, when compared to what the carpet has to absorb coming from drivers on R7 Meta, for left and right).

I'm open to suggestions, if there's something more effective that would not completely destroy the aesthetics of the room (I'm not against aesthetic compromises but there are limits).

 

[MarsianC#]

At 1.12 ms? or 384 mm longer path. I don't think that is the shelf though. Simulate it with this tool: https://amcoustics.com/tools/amray
Left main has the exact same reflection. Right looks way better?
You could lower the center and angle it up a bit more and check if in makes any difference.
A carpet won't help with low freq.

 

[DVDdoug]

According to Floyd Toole, early reflections can actually be beneficial!

The treatment of early reflections boundary areas is "optional": reflect, diffuse, or absorb, as the customer prefers.

In the field architectural acoustics it has long been recognized that early reflections improve speech intelligibility.

Early (sound) reflections had the same desirable effect on speech intelligibility as increasing the level of the direct sound... Late reflections (including reverberation) are undesirable, but reducing them should not be the first priority, which is to maximize the total energy in the direct and early-reflected speech sounds. Remarkably, even attenuation the direct sound had little effect on intelligibility in a sound field with sufficient early reflections.

For speech intelligibility - a crucial consideration for movies - it is early reflections that are the main contributors. Early refection energy arriving within about the first 50 ms following the direct sound has the same effect on speech intelligibility scores as an equal increase in the direct sound energy.

It is fair to say that the more similar the early reflections curve is to the direct sound curve, the more favorable is the perceptual result in both timbral and spatial respects.

 

[Jost Buergi]

At 1.12 ms? or 384 mm longer path. I don't think that is the shelf though. Simulate it with this tool: https://amcoustics.com/tools/amray
Left main has the exact same reflection.

I agree. Possibly a first reflection from the front wall or TV? What really helped me in finding a couple of first reflection points was a small mirror (cheap and lightweight plastic mirror tiles) and a laser meter. Gave me some real surprises.

Regarding absorption material: after doing some research I do use Basotect. Afaik one of the most (if not the most) efficient absorption materials when you are restricted to using thin (under 10 cm or so) panels. I would buy some pieces and try and remeasure with REW. Cutting residues of Basotect can be had real cheap and be just right for some testing.

 

[goat76]

According to Floyd Toole, early reflections can actually be beneficial!

Don't you think the speech intelligibility beneficial early reflection should be part of the recording, and therefore come as either real or artificial reverberation with the direct sound?

I find it a bit strange if Toole truly thinks strong early reflections from the listening environment are needed to make the recorded information "complete and fulfilled".

 

[goat76]

A first suggestion was to place the speaker at the front of the shelf. But that, to be honest, would be aesthetically unacceptable for me. It would distract me enormously, making me concentrate all the time on the speaker itself, instead of music and/or video content (I know myself, it happened in a past setup).

That would be my suggestion too, and I think you should try the front-of-the-shelf placement for a couple of weeks until you get used to how it looks.

 

[gorman]

That would be my suggestion too, and I think you should try the front-of-the-shelf placement for a couple of weeks until you get used to how it looks.

I understand where you're coming from, really. But it looks like s%£$... R6 Meta is too big to sit there. I really could not bear it in that position. Be patient with me, as I have stated I'm open to compromises but that... is going too far.

 

[gorman]

Left main has the exact same reflection. Right looks way better?

It could be the side wall... or the window. But I have taken measurements with heavy curtain drawn and it did not make any difference (we cannot know the frequency of the reflections or can we? Because if it's for low frequency no wonder the curtain does little).

Measurement file with curtains drawn or not can be downloaded from here: https://easyupload.io/u408za (reposting from the other discussion). It contains Audyssey measurements too as I wanted to compare group delay in the bass region (where Dirac behaves strangely).

 

[Jost Buergi]

But I have taken measurements with heavy curtain drawn and it did not make any difference

It indeed should have resulted in some sort of effect. Plus that 1.1 ms seems to be too much delay in this case. How much is the front wall distance? It’s easier for you to find out than for us, see my post above.

 

[sanmateo]

if you really want to stop those reflections, surface geometries which scatter and diffuse might be more effective than trying to absorb all the energy. Anechoic chambers rely on a combination of absorption and scattering. Perhaps you could get something like this that wouldn't be too ugly (or at the very least it would provide another variable for your measurements.)

the stuff I saw online was called "isowedge" but I don't have first hand experience with it.

 

[gorman]

if you really want to stop those reflections, surface geometries which scatter and diffuse might be more effective than trying to absorb all the energy. Anechoic chambers rely on a combination of absorption and scattering. Perhaps you could get something like this that wouldn't be too ugly (or at the very least it would provide another variable for your measurements.)

View attachment 428084
the stuff I saw online was called "isowedge" but I don't have first hand experience with it.

Two of these, maybe, one next to the other?

https://amzn.eu/d/5Txk7EQ

They are 31.5 x 31.5 x 6 centimetres.
R6 Meta is 62cm wide, two of these would be 63cm. And there's exactly 31.5cm in front of the speaker, to the end of the shelf.

 

[sanmateo]

because of the vertical surfaces I imagine you'd have some reflections back to the tv, adding a second bounce with even longer delay. The diagonal stuff at least would bounce energy toward the ceiling.

why not experiment with some sheets of cardboard folded like an accordion?

 

[RayDunzl]

This is the placement in my room (taken from previous discussion):

My TV as well as the speakers to the sides, is flush with the front of the rack, so, if I had a center channel speaker, it wouldn't be an issue, but I don't, so it isn't.

Just measured... The TV is 4 feet out from the wall. It uses a telescoping wall mount that I mounted to the back of the rack using some angle iron.

Grok 2 says:

Viewing a 75-inch diagonal TV from 10 feet would be equivalent, in terms of viewing angle, to viewing a 105-inch diagonal TV from 14 feet.

Hey! I saved on getting a bigger TV!

 

[gorman]

Just measured... The TV is 4 feet out from the wall. It uses a telescoping wall mount that I mounted to the back of the rack using some angle iron.

The way you see it in the photo, my eyes are about 8 feet from the screen, on a 77".

 

[sanmateo]

If it makes you feel any better, I sit 15 feet from my 32" television.

 

[RickS]

just a thought...

Move the center to the front of the equipment cabinet and move the tv behind it (or even on top of it?). Move the subwoofers to back or sides (or somewhere else entirely) to get the left speaker away from the wall and closer to the tv and adjust right accordingly.

 

[gorman]

If it makes you feel any better, I sit 15 feet from my 32" television.

It's a more relaxing experience. And I'm not mocking you.

Move the center to the front of the equipment cabinet and move the tv behind it (or even on top of it?). Move the subwoofers to back or sides (or somewhere else entirely) to get the left speaker away from the wall and closer to the tv and adjust right accordingly.

As I have stated, the center so far in front from the TV would be aesthetically abhorrent to my eyes. Plus, when I use my reclining couch, it would mean my feet would be directly in front of it. No, thanks

As far as the sub... I had the speakers inverted with subs. Bass response was worse (unfortunately I have not saved measurements, at least I don't think so, I could search more but I've searched already).

Thanks for your input, though!

 

[Chrispy]

I don't have my center on a shelf like that....it's on a riser to maximize distance from floor but still a good angle to my ears, and below the display (didn't want to try above, altho I'd done that before with a really big crt rear projection set)

 

[Keith_W]

I should point out that just because you can see it on measurements, it does not mean it will sound bad. My advice is to pull your speaker to the front of the shelf and have a listen. I doubt it will sound substantially better than where you have it at the moment. Then you can push it back to where it is and sleep in peace.

It is tempting to read too much into measurements. I am guilty of that myself. I see something, I worry about it, I spend a lot of effort fixing it ... and it doesn't sound any different. Most of the time the "improvement" is so subtle I doubt I could pick it in a blind test. You can try it. Wear a blindfold, ask your wife to move the speaker forward and backward. Think you can tell the difference?

 

[gorman]

It is tempting to read too much into measurements. I am guilty of that myself. I see something, I worry about it, I spend a lot of effort fixing it ... and it doesn't sound any different. Most of the time the "improvement" is so subtle I doubt I could pick it in a blind test. You can try it. Wear a blindfold, ask your wife to move the speaker forward and backward. Think you can tell the difference?

Oh, I'm not so... worried? I asked this question just to see if there was a quick way for me to check a different arrangement of things. The R6 Meta on its stand, perfectly centered is... not something I'd ask my wife to move for me. First, it's heavy and unwieldy to move. Second it would mean me having to remeasure everything when I put it back (measuring its position, more Dirac measurements are not what worries me).

Keith, since I have you here: in my original measurements thread you commented on RT60 being "lowish, at about 200ms" and inquired about room size and acoustic treatment.
I provided an answer here: https://www.audiosciencereview.com/...-will-help-me-analyse-them.60666/post-2222082
I would love to hear your thoughts on this. Maybe too much absorption? I don't know what you meant with the original comment. Although your "looks great to me" was of great comfort during these past few days where I've tried to understand all the intricacies that measurements expose. Thanks!