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What to do when speakers can't be placed in ideal location?

Marth

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I have speakrs with great directivity and don't have any reflection from sidewalls and frontwall. I tested QRD diffusion between the speakers with a 2m*1,5m area and there was no audible difference and almost no difference in the ImpulseResponse (reflections.) As I have heavy absorption on the backwall I wouldn't have expected combfilters between front and backwall anyway. Without any backwall absorptions or diffusion, diffision on the frontwall will help with combfilters.

Combfilters in general are responsible for almost all waviness in your frequency plot.
Most of these simple two-way designs sound best in a room with comfortable furniture. Before concentrating on wall treatments, get a nice couch.
Exactly! For the higher degree reflections furniture is best to manage the reverb in a room. Depending on the speakers, furniture can even be enough for first order reflections. However when it comes to the ceiling you do need some treatment... floor not so much as our brain is used to that reflection.
 

tecnogadget

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Personally I would not apply any type of acoustic treatment without having a calibrated microphone and being able to make measurements. Otherwise you would be doing everything blindly, which makes no sense at all, you would never be sure of what you are doing. Besides, if you do not perform an acoustic measurement before applying treatment, you would not know which parameters should be prioritized in your room. Illogical, isn't it?

In any case I would always try to solve problems below the transition frequency in the low frequencies first. I prefer to solve it with DSP. And if it is about acoustic treatment, "real" bass traps this are pressure absorbers (membrane/diaphragmatic/helmholtz/etc) instead of velocity absorbers (typical useless foam panel with triangular corner shape).

In a second step I would be concerned about reducing unwanted reflections and reverberation times above the transition frequency (mid and high frequencies). Normally with porous panels or a mixture of these with diffusion.

Finally, I recommend not to be obsessed with the subject, and to make life easier at least above the transient frequency by means of loudspeakers with good dispersion and directivity.
 

tecnogadget

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Most of these simple two-way designs sound best in a room with comfortable furniture. Before concentrating on wall treatments, get a nice couch.
I agree with you ;).
Most of us get too obsessed with acoustic treatment. I have gone from a fully treated room (avatar) to a normal room, but with the difference of speakers with excellent horizontal and vertical directivity...and I am not saying that there is no difference...but from an audibility point of view, and considering how the brain can filter out many aberrations...I can assure you that I do not feel that I have lost so much between one room and another, the difference between both cases is very much shortened with DSP.
 

abdo123

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Headphones are not well suited to truly create the auditory illusion needed to trick you into feeling as if you are there imo. Little natural head movements and all that. Your brain isn't stupid. Maybe if you sit extremely still and have headphones resting on your ears without any pressure. So far no headphones have been able to do that for me. Theory also explains that earphones have a high degree of spartial distortions and in-head localization is different.

When I close my eyes only loudspeakers have so far been able to create that illusion for me. For tonality they could be better but good speakers and a room where the reflected sound still has all frequency components also works well. You don't need to remove all reflected energy or diffuse it. In a living environment it is enough to make sure that the spectrum of direct and reflected sound is similar...


That doesn't change that Headphones will provide you a better experience when you don't have the 5000$-10000$ necessary to get a decent set-up and make a decent room.
 

Marth

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Just check your impulse response! If should show a steady decay over time without later peaks exceeding earlier peaks. This is achieved by a combination of muting the large peaks (1st and 2nd order) and by scattering (via furniture) the higher order reflection to create a homgeneuous reverb field.

Here is mine without backwall absorption. All peaks you see are from ceiling, floor and backwall interaction. Frontwall and sidewalls are absent due to the dipol/cardioid radiation pattern of my speakers.


It is not rocket science.

For diffusion you have to use QRDs... skyline diffusors lack the well walls which are important. use 1D QRD and if you need 2D diffusion you take 4 1D diffusion panels and arrange them accordingly.

ImpulseResponse.jpg
reflections within 40ms.png
 

youngho

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I have a room where the layout won't allow the speakers to fire down the length of the room. Instead, they need to be in the middle of the long wall, firing across the width of the room. I know this isn't ideal, but it's what I have to work with for the time being.

With that in mind, I'm wondering what acoustic treatments I might try to mitigate the less-than-ideal speaker placement. I'm not sure if diffusers or absorbers on the wall behind the listening position would be best. Additionally, I'm wondering if it may be beneficial to place the speakers fairly far apart.

View attachment 155038View attachment 155039

As you can see the room has sloped ceilings. Currently I just have a few rigid fiberglass panels in two of the corners. I have a microphone on the way so I can start taking some measurements.

It's funny, this setup reminds me of the old Audio Physic loudspeaker setup recommendations:

Otherwise, the thickest absorption you can fit behind the listening position would be preferable.
 
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Epos7

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Before concentrating on wall treatments, get a nice couch.

I do have a nice comfy couch. It's leather, and I wonder if that would reflect more than a fabric couch? I'm more concerned about the glass coffee table in front of it. I think I'll switch to a smaller walnut one.
 

Jim Matthews

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I do have a nice comfy couch. It's leather, and I wonder if that would reflect more than a fabric couch? I'm more concerned about the glass coffee table in front of it. I think I'll switch to a smaller walnut one.
It's a reasonable concern. I believe our very own Kal(the Man) Rubinson has made pointed mention of this common placement problem when reviewing other listeners systems.

It's also simple to test...

Play your favorite, familiar music with the coffee table in place.
Repeat the tune with it moved to one side.

****

I'm imagining a nice rug between your Epos and the couch, matching side tables flanking the seating.

download.jpeg
 
Last edited:

Kal Rubinson

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Epos7

Epos7

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I'm imagining a nice rug between your Epos and the couch, matching side tables flanking the seating.
Check. I've got a 9' x 10' wool rug in the middle of the room. It's not a super thick/plush rug but does have a 1/4" felt/rubber rug pad underneath. In addition to that I have two smaller wool rugs with rug pads flanking it.
 

Marth

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It's funny, this setup reminds me of the old Audio Physic loudspeaker setup recommendations:

Otherwise, the thickest absorption you can fit behind the listening position would be preferable.
Can approve this. When you have a small room it is extremely benficial if you remove one wall by adding thick absorption to it. I am referring to a minimum of 8 inches rockwool velocity bass traps + AVAA C20 unit or 14inches rockwool velocity bass traps.

Both approaches will deaden the wall from 40Hz up to 16k+Hz. This will remove many combfilter and at least one major room mode!

In many cases this is even possible in a living space. Makes physical room smaller but makes the acoustical room much much larger.
 
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Epos7

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I am referring to a minimum of 8 inches rockwool velocity bass traps + AVAA C20 unit or 14inches rockwool velocity bass traps.
What density of rockwool are you referring to?
 
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