Advise on what Rock/mineral/glass wool to choose for basstraps

All about acoustics. This is your new home if you already have a studio or other acoustic space, but it isn't working out for you, sounds bad, and you need to fix it...

Which insulation product would you choose for bass traps ?

Poll runs till Sun, 2020-Nov-29, 18:23

Knauf Ultracoustic-p
0
No votes
Fibran b030
1
100%
Fibran b040
0
No votes
Fibran b050
0
No votes
 
Total votes: 1

musictracer
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Advise on what Rock/mineral/glass wool to choose for basstraps

#1

Postby musictracer » Mon, 2020-Feb-03, 18:23

Hello everyone and good luck with this beautiful new forum to you Stuart and your team! :D

I have "designed" and currently building a couple of Bass Traps for my room and I find it hard to decide which product of porous absorbing material I should use.
Unfortunately where I live I can't get owen's curning or Rockwool Safe n' sound.

Thus my choices are narrowed to this table:
products 2 - no isover or izifon.jpg
.

Preferably I'd like to avoid exceeding the 40kg/m3 in order to make the traps lighter.
According to the porous absorber calculator, the 5 kpa.s/m2 will work better for the lows, so the ultracoustic-p is on of my 2 top candidates here. Has anyone used that, and if yes how did it perform?

On the other hand my other top candidate is the b-040 which shows better absorption at the lowmid area, but in a conversation I had with Stuart in another forum some time in the past he recommended around 7 kpa.s/m2 for low freq absorption, while this one is 15 kpa.s/m2, so I would pick b-030 over this. Problem is the company hasn't published any absorption coefficient data for this product, but judging by the coefficient difference between the b050 and b040, I guess the b030 coefficient should be slightly greater than 0,22 @125hz which is the best choice of all for me. (By the way, b050, b040 and b030 correspond to 50, 40 and 30 kg/m3 densities respectively ;-) )

Also it is good to mention that Stuart's recommendations align with Porous Absorber Calculator which confirms that 5 kpa.s/m2 (ultracoustic p ) will work better than 10 kpa.s/m2 (b030) at the dimensions of my traps .


So right now I am in a dilemma between those two products.

I am making two corner traps (see pics), both on the front wall. Geometry and size of each one is due to the shape of my room (which you can see in the pictures bellow) and the lack of more space.

So, as the thread title states, I am having trouble picking the right product of insulation. Which one would you recommend and why?

Thank you beforehand!

Ps. The triangular bass trap will be including only one divider (in the middle), not 3. This means that each one of the 2 parts of insulation will be roughly 70cm tall.
Attachments
fibran b-040.jpg
knauf ultracoustic - p.jpg
triangular bass trap - fixed.jpg
rectangular bass trap - fixed.jpg
6. over front left side.jpg
5. over front right side.jpg
4. over back right side.jpg
3. above .jpg
2. over back left side.jpg
1. left side.jpg



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Re: Advise on what Rock/mineral/glass wool to choose for basstraps

#2

Postby Soundman2020 » Tue, 2020-Feb-04, 23:45

Hi there, and welcome to the new forum! :thu: :)

Hello everyone and good luck with this beautiful new forum to you Stuart and your team!
Thanks! Glad you found us, and glad you joined up too!

Regarding your choice of insulation, it looks like the Fibran 30 (or maybe the Fibran 40) would be the best for what you need.

Preferably I'd like to avoid exceeding the 40kg/m3 in order to make the traps lighter.
I wouldn't worry too much about weight: your traps are have a volume of less than 1 m3, so the weight is only going to be about 35 kg or so (including the wood). That's not so heavy. But if you are very concerned about weight, then yes, the Ultracustic would be the best from that point of view.

However.... ( :) ) I think your room layout could probably be improved a bit. It's a small room, so it would be beneficial to do as much as you can to improve it. Here's what I would suggest:

[list=]
[*]Rotate the orientation 90° to the right, so you are facing the double doors. I'm hoping that you don't need to use those doors?
[*]Get rid of the book case ad closet if you can: they are taking up a lot of space in the room. That might not be possible, I know, but it would help a lot if you could
[*]Get your speakers off the desk and onto stands behind the desk. Use heavy, tough stands, not light-weight ones.
[*]Get your speakers up against the front wall, as close as you possibly can.
[*]In addition to the bass traps in the corners, I would also put more trapping in some of the wall/ceiling corners
[*]You have a bed in there, and you are going to have lots of bass trapping too, so the room is going to end up sounding very "dry", with very short decay times. You will probably need to put plastic sheeting over the front of your bass traps to reflect back some of the highs into the room, and also broad wood slats, to reflect back some of the high-mids and highs.
[*]If there is carpet on the floor, consider removing that, since it is not doing good things to your room (see here: viewtopic.php?f=16&t=149 )
[*]Before you do anything in your room first do a test with REW, to see how it is doing right now (See here: How to calibrate and use REW to test and tune your room acoustics )
[/list]

Small rooms are the hardest to get good, but there's always somethings you can do to make it better! And you seem to be on the right path.

- Stuart -



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Re: Advise on what Rock/mineral/glass wool to choose for basstraps

#3

Postby musictracer » Wed, 2020-Feb-05, 08:35

Thanks! Glad you found us, and glad you joined up too!

You are welcome! Pleasure is mine of course! :D

Regarding your choice of insulation, it looks like the Fibran 30 (or maybe the Fibran 40) would be the best for what you need.

I was indeed leaning to b030 to be honest! I'm glad you recommended this one. But now you put me in a new dilemma between this and the b040 :( . Now I know that probably it isn't going to make much of a difference no matter which one I choose of the two since little differences in the absorption coefficients don't influence acoustic efficiency that much (ie. the bobgolds coefficient chart we all get advise from for years now whenever we need to clearly states in the 3d line of the 2nd sentence:

"Differences in coefficients of less than 0.15 are not significant."

https://www.bobgolds.com/AbsorptionCoefficients.htm )

Weight wise I would benefit from using the b030 since it would make the corner trap 5kg lighter.

Sagging wouldn't be a problem since when I spoke with them on the phone they assured me that it is unlikely to occur bellow a 2 meters stack. Though I can't recall if that info regards the 040 or the 030, I still believe I'll be fine with my 0,70m - 0,75m stacks no matter which one I choose!

But the factor I am mostly concerned about is the GFR of the two. The 030 is 10kPa.s/m2 while the 040 is 15kPa.s/m2 . And I remember you once recommended around 7 kPa.s/m2 or a little less for bass traps. Now, by "playing" a bit with the porous absorption calculator I can see that the 030 benefits with an around 0.6 - 0.8 larger coefficient at the lows. But probably, as stated above, that wouldn't make a significant difference, and the fact that the 030 lacks coefficient measurement by the company confuses thing even more.
Dunno, I need your thoughts with this!

As for your recommendations, they are much appreciated though I have thought most of them in the past and couldn't realize due to a few reasons:

[*]Rotate the orientation 90° to the right, so you are facing the double doors. I'm hoping that you don't need to use those doors?

This is the exit to my balcony. Not used so often indeed, but if I bring the desk with the speakers and the sbir panel against it I will lose 50% of the light coming in the room, while at the same time the other 50% will be coming directly to my face, forcing me to pull the curtains shut, thus having no light in the room. Also, none of the balcony doors would be able to open, since the desk should be right against the doors...

[*]Get rid of the book case ad closet if you can: they are taking up a lot of space in the room. That might not be possible, I know, but it would help a lot if you could

Correct! No can do, sorry! I know it would be beneficial but there is no room elsewhere in the house to put it. At least it provides some sort of diffusion (or maybe I should say scattering to be more accurate) which is good for me I suppose.

[*]Get your speakers off the desk and onto stands behind the desk. Use heavy, tough stands, not light-weight ones.

I am afraid neither that is possible. There is no room for that either.

[*]Get your speakers up against the front wall, as close as you possibly can.

This might be an option , but that would make the desk reflecting sound to the sweet spot, but even if I moved them, it wouldn't be more than 10cm since that is their distance from the sbir panel. Should I benefit from that, despite creating desk reflections? And speaking of sbir panels, I think I should make a new one covering the whole desk width wise, so that it is covering the back of the speakers too, do you agree? Also I will be using this product: https://alphacoustic.com/wp-content/uploads/2013/09/iZiFON-%CE%BC%CE%BF%CE%BD%CF%89%CF%84%CE%B9%CE%BA%CF%8C-%CE%B9%CE%BD%CF%8E%CE%BD-%CF%80%CE%BF%CE%BB%CF%85%CE%B5%CF%83%CF%84%CE%AD%CF%81%CE%B1.pdf
The coefficient plot of the one I'll be using is the blue one (see 2nd page), the one with the greatest absorption @125hz. It is a polyester product with a 20kg/m2 density, so it is very light and looks quite efficient for sbir panels. (I know what you might be thinking, it would be great for the traps too, but problem is it is quite costy compared to the other alternatives ;) ) I assume 20cm thickness should be fine for a sbir panel, right?

[*]In addition to the bass traps in the corners, I would also put more trapping in some of the wall/ceiling corners

That would be beneficial indeed, but I really don't want to hurt the walls even more. I know the room is not the best for what I want to do , so I will probably be moving some time in the future in an other one, so I don't want to leave many holes behind :lol: .

[*]You have a bed in there, and you are going to have lots of bass trapping too, so the room is going to end up sounding very "dry", with very short decay times. You will probably need to put plastic sheeting over the front of your bass traps to reflect back some of the highs into the room, and also broad wood slats, to reflect back some of the high-mids and highs.

Yes, I have thought that this is possible to happen also, this is why I am thinking of making the front face fabric of my traps removable (attached with velcro) so that I can edit the inside of it at will. I would just prefer not to edit the trap construction if possible, so I would like to avoid using lumber sluts for example. Our dear friend Gregwor once spoke to me about vapor barrier. It seems easier to attach. Do you think it might be enough if needed? (Probably impossible to answer without measurements, but I thought I might ask beforehand :) )

[*]If there is carpet on the floor, consider removing that, since it is not doing good things to your room (see here: viewtopic.php?f=16&t=149 )

I won't be using any, since I will be using an 1.60x1.20x0.40 m cloud too. . That will absorb a lot of hi freq energy, so putting a carpet as well will be suicidal I suppose :lol:

Sorry for not mentioning the cloud before, I have so much in my mind to deal with... I will be using the polyester product I mentioned before. Do you think it should cover only the ceiling first reflection, or should I consider covering the area above the speakers, or the listener - if possible ?

[*]Before you do anything in your room first do a test with REW, to see how it is doing right now (See here: How to calibrate and use REW to test and tune your room acoustics )

I had a few measurements a year ago, but I will take new ones since I lack the mic I used back then, and I have edited the settings of my sub a bit since then as well. Here is a comparison of the empty vs side+sbir panels in place measurements.

sbir + side.jpg


The red line is the empty space. I know it didn't seem to do anything significant, though I admit a saw some slight improvement with the RT60 times. Of course placement of the panels was done with the moving mirror method and it is as seen in the sketchup pics I uploaded. Insulation I used is this one: http://www.metaxiotis.gr/xml/pdf/NavisionLinks/Item%20Technical%20Data/FIBRAN/GEOLAN/TDS%20FIBRANgeo%20B-051%20%20gr.pdf . You can see that it is quite efficient (0.35 @125hz) though quite heavy (150kg/m3), but it didn't perform like I expected to... [Please bare in mind that it is likely (can't remember) that I had a carpet on the floor when taking these measurements, which of course I have removed already. ]

Small rooms are the hardest to get good, but there's always somethings you can do to make it better! And you seem to be on the right path.

Thanks so much for your encouragement and assistance! It is so valuable to me as well as the rest of us in here ! :D

P.S. Yesterday I got a spam p.m. from a user nicknamed "Robertvew". Probably you have already blocked him by now, but I thought it would be good to mention in case you haven't. :-)
Attachments
FR+SBIR (20 - 20000 hz).rar
m.dat file of the measurements
(2.51 MiB) Downloaded 11 times
FR+SBIR (20 - 20000 hz).rar
m.dat file of the measurements
(2.51 MiB) Downloaded 11 times



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Advise on what Rock/mineral/glass wool to choose for basstraps

#4

Postby Soundman2020 » Tue, 2020-Feb-11, 14:01

Now I know that probably it isn't going to make much of a difference no matter which one I choose of the two since little differences in the absorption coefficients don't influence acoustic efficiency that much (ie. the bobgolds coefficient chart we all get advise from for years now whenever we need to clearly states in the 3d line of the 2nd sentence: "Differences in coefficients of less than 0.15 are not significant."
True, but it's still better to go for the best you can get, in general.

Sagging wouldn't be a problem since when I spoke with them on the phone they assured me that it is unlikely to occur bellow a 2 meters stack. Though I can't recall if that info regards the 040 or the 030, I still believe I'll be fine with my 0,70m - 0,75m stacks no matter which one I choose!
You should be fine. Even if you do get a little sagging, it's not going to be a lot. Compression up to about 20% is usually still OK for most insulation.

But the factor I am mostly concerned about is the GFR of the two. The 030 is 10kPa.s/m2 while the 040 is 15kPa.s/m2 . And I remember you once recommended around 7 kPa.s/m2 or a little less for bass traps.
Around 5k to 15k rayls GFR is the "sweet spot" for bass trapping, for most types of porous absorber. That's why I mentioned 7k in that post you mentioned, as roughly the mid point.

Now, by "playing" a bit with the porous absorption calculator I can see that the 030 benefits with an around 0.6 - 0.8 larger coefficient at the lows. But probably, as stated above, that wouldn't make a significant difference, and the fact that the 030 lacks coefficient measurement by the company confuses thing even more.
You are probably "over-thinking! this a bit! :) Either of those products is going to give you good absorption in the low end. Make it thick, and floor-to-ceiling, and you'll have good results in both cases.

Not used so often indeed, but if I bring the desk with the speakers and the sbir panel against it I will lose 50% of the light coming in the room, while at the same time the other 50% will be coming directly to my face, forcing me to pull the curtains shut, thus having no light in the room. Also, none of the balcony doors would be able to open, since the desk should be right against the doors...
A conundrum indeed! :) Three things to consider here: 1) you might not need SBIR panels across the glass: it might be sufficient to just have them from the room corner up to the edge of the speaker. You could do some testing to see if that is effective or not. 2) Maybe you could set up your video screen directly in front of the window, so you don't have too much light straight into your face? 3) Are you going to be using your room for mixing mostly during the day, or mostly at night? If it will be at night, then you don't need to worry too much about daylight in your face...

Correct! No can do, sorry! I know it would be beneficial but there is no room elsewhere in the house to put it. At least it provides some sort of diffusion (or maybe I should say scattering to be more accurate) which is good for me I suppose.
Maybe.... But not that much. If you can't move the bookshelf, then just fill it with insulation. Put some of that 030 in all of the shelves. Also, take the doors off the closet and do the same: fill the interior with insulation. Those would make pretty good bass traps, filled completely with insulation.

I am afraid neither that is possible. There is no room for that either.
Then get a smaller desk! :) With your speakers on the desk as shown in your images, you are going to have several problems, such as:

1) SBIR: the speakers are too far away from the front wall. If you look at the diagram below, from Neumann, you can see that you need to have a distance of no more than about 20 cm between the FRONT face of your speaker (the woofer cone), and the front wall. That normally means that you need to have the speaker tight up against the front wall, with the rear corner almost touching the wall, then perhaps have some low-density porous insulation around the speaker, but taking care not to block good air circulation.
neumann_loudspeaker_boundary_location_v02-SBIR-TABLE-wall-bounce-distance.jpg


2) Vibrations: The speakers will induce vibrations in the desk itself, which will be re-radiated into the room. Using sponge pads to try to isolate this does not work very well. Ethan Winer did a series of tests on commercial "speaker isolators" and a couple of other things, and showed quite convincing that they don't do much: the vibrations still get into the desk.

3) "Early-early sound". In other words, sound that arrives at your ears BEFORE the direct sound from the speakers. This is related to #2 above. Sound travels much faster through the wood of your desk than it does through air, so any vibrations in your desk could be re-radiated from an area closer to your ears, and thus arrive at your ears before the direct sound does.

4) Reflections. Some of the sound will reflect off the desk, into your ears, which messes up your psycho-acoustic perception of the sound. Since the reflection arrives within just a couple of milliseconds of the direct sound, your brain is unable to determine that it is a reflections, and instead decides that the sound came from a different direction, and with a different frequency response...

5) Comb filtering. Relate to #4: When you have two copies of the same sound arriving at your ears, with slightly different timing (phase"). This causes a series of dips and peaks in the frequency response of the sound that you hear. This graph shows the general concept:
comb-filter-concept.jpg
That's the frequency response that you get from comb filtering. You can see that the shape of the waveform looks a bit like a comb, hence the name. Here's a comparison of the direct sound and the comb-filtered sound:
comb-filtering-1--direct-vs-combined.jpg
The flattish line at the top is the direct sound, as it came out of the speaker, the "bumpy" line is what you actually hear when that direct sound is combined with a delayed copy of itself. And here's a real-world example:
Comb-filtering-frequency-response-1ms.png
In this case, the reflected sound is delayed by about 1 millisecond. There are a few techniques for dealing with this, such as angling the desk surface a bit (so it is not flat any more). Doing that can produce this:
Desk-surface-comb-filtering-red-is-flat-blue-is-angled-toward-mix-pos-slightly.jpg
You can see the improvement: the red line is the original comb-filtered signal with the desk flat, and the blue line shows the result after angling he desk a little towards the mix position. Improved, but it is still not good. It's better to avoid this entirely (or at least reduce it as much as possible), by getting the speakers off the desk, onto stands behind the desk.

This might be an option , but that would make the desk reflecting sound to the sweet spot
You are getting that in any case! See above... Also, your speakers are probably too close to your ears if you have them in the position you show. The graph below is from Springer's "Handbook of Acoustics", in the section about speaker placement.
what-near-field-really-is.jpg
what-near-field-really-is.jpg (32.98 KiB) Viewed 134 times
what-near-field-really-is.jpg
what-near-field-really-is.jpg (32.98 KiB) Viewed 134 times
It shows how the frequency response varies according to how far you are away from the speaker. As you can see, being too close to a speaker is not a good thing! There are wild swings in frequency response...

but even if I moved them, it wouldn't be more than 10cm since that is their distance from the sbir panel.
Once again, you are up against a "conundrum"! :) As with most things in small studio design, you often have to "trade off" one thing for another. In your case, considering that the room is so small, I would suggesting pushing the speakers all the way up to the wall, so the rear corner is almost touching the wall, then setting up your SBIR panels vertically, not horizontally: two of them. One just next to the left of the left speaker, then other just to the right of the right speaker.
Should I benefit from that, despite creating desk reflections?
You already have desk reflections, vibrations, and comb-filtering....
And speaking of sbir panels, I think I should make a new one covering the whole desk width wise, so that it is covering the back of the speakers too, do you agree?
As above: I would create a sort of "C" shaped panel, where the speaker is in the middle of the "C", surrounded on three sides by the absorption, with the rear corner of the speaker almost touching the wall (or window! :) ).

The coefficient plot of the one I'll be using is the blue one (see 2nd page), the one with the greatest absorption @125hz. It is a polyester product with a 20kg/m2 density, so it is very light and looks quite efficient for sbir panels. (I know what you might be thinking, it would be great for the traps too, but problem is it is quite costy compared to the other alternatives ;) ) I assume 20cm thickness should be fine for a sbir panel, right?
With the speaker against the wall, as above, you could probably use 10cm thickness. When you make those new panels, do be careful that you leave some space for air to circulate behind the rear of the speaker, for cooling.

Yes, I have thought that this is possible to happen also, this is why I am thinking of making the front face fabric of my traps removable (attached with velcro) so that I can edit the inside of it at will.
:thu: Sounds like a good idea!

once spoke to me about vapor barrier. It seems easier to attach.
Welllll.... yes and no. Plastic can be useful, but it might not go down low enough. Technically, it is a "foil", and it reflects some frequencies while allowing others through. The frequency range is determined by the thickness, or rather the density, of the foil. Here's a graph that shows the effect for a few different densities of plastic, when used in front of a porous absorber:
effect-of-plastic-sheet-foil-on-porous-absorber-2.jpg
So you would need to to do some testing to find out what frequency range you are losing too much of, then add the right thickness plastic accordingly. However, you cannot do that on your first reflection point absorbers! Only on your bass traps and SBIR treatment.

Sorry for not mentioning the cloud before, I have so much in my mind to deal with... I will be using the polyester product I mentioned before. Do you think it should cover only the ceiling first reflection, or should I consider covering the area above the speakers, or the listener - if possible ?
Generally, for small rooms like yours I recommend using an "angled, hard-backed ceiling cloud", over the area between the speakers and the listening position. The angle and hard back help to redirect some of the sound towards the rear wall, where it can be absorbed more, and can also be beneficial for vertical modal problems.

I had a few measurements a year ago, but I will take new ones since I lack the mic I used back then, and I have edited the settings of my sub a bit since then as well. Here is a comparison of the empty vs side+sbir panels in place measurements.
That looks like you did the testing with both speakers on, and with the levels a bit too low. There is some comb-filtering evident there. Take a look at the tutorial I linked you to before, to see the full procedure.

P.S. Yesterday I got a spam p.m. from a user nicknamed "Robertvew". Probably you have already blocked him by now, but I thought it would be good to mention in case you haven't.
Right! I fixed him real quick, as soon as I found him. That was my fault, for not having turned off the ability to send PM's for spammers. I fixed that now. Over the last few days we have had some pretty intense attacks by spammers: hundreds of spam posts, many dozens of fake new members (mostly from Russia and the Ukraine!). The anti-spam measures and yours-truly managed to kill most of those, with forum members never even seeing the vast majority, but a couple did get through. Sorry about that! I also added some new anti-spam features to the forum. I'm trying to improve it all the time. If it happens again, please send me a PM (Private Message), as I will probably see that sooner than a comment in a thread.

- Stuart -



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Advise on what Rock/mineral/glass wool to choose for basstraps

#5

Postby musictracer » Thu, 2020-Feb-13, 19:05

Soundman2020 wrote:Source of the post True, but it's still better to go for the best you can get, in general.

And that's exactly what I hope I did! :) Today I got the b030 delivered to my home!

Soundman2020 wrote:Source of the post You should be fine. Even if you do get a little sagging, it's not going to be a lot. Compression up to about 20% is usually still OK for most insulation.

Great! To be honest I wasn't concerned too much about the performance due to sagging , but mainly for the aesthetic result .

Soundman2020 wrote:Source of the post Around 5k to 15k rayls GFR is the "sweet spot" for bass trapping, for most types of porous absorber. That's why I mentioned 7k in that post you mentioned, as roughly the mid point.

Nice! I went for the 10k eventually!

Soundman2020 wrote:Source of the post You are probably "over-thinking! this a bit! Either of those products is going to give you good absorption in the low end. Make it thick, and floor-to-ceiling, and you'll have good results in both cases.

It's true, I am over-thinking quite often. But it's just that I haven't got practical experience on acoustics despite having studied Music Technology and Acoustics Engineering. Once again, thanks for your valuable assistance! :D

Also you
Soundman2020 wrote:Source of the post A conundrum indeed! Three things to consider here: 1) you might not need SBIR panels across the glass: it might be sufficient to just have them from the room corner up to the edge of the speaker. You could do some testing to see if that is effective or not. 2) Maybe you could set up your video screen directly in front of the window, so you don't have too much light straight into your face? 3) Are you going to be using your room for mixing mostly during the day, or mostly at night? If it will be at night, then you don't need to worry too much about daylight in your face...

I appreciate your recommendation for moving the desk up against the balcony door, but I am afraid that it is not possible. I mean, it's true that not only would it help with delaying the reflections from the back wall, but it would also provide more stereo balance due to equidistant boundaries on either side of the sweet spot. So I spent some time sketching-up yesterday trying hard to find an efficient placement of the furniture to accomplish that but there were problems I couldn't resolve, like the fact that both balcony doors should remain permanently shut for example.

Soundman2020 wrote:Source of the post If you can't move the bookshelf, then just fill it with insulation. Put some of that 030 in all of the shelves. Also, take the doors off the closet and do the same: fill the interior with insulation. Those would make pretty good bass traps, filled completely with insulation.

Well, if I were able to fill them with insulation, I would rather remove them instead and make absorption panels anew. :D But maybe I never mentioned it and thus got you confused with the sketchup drawing. Both the bookshelf and the wardrobe are filled with books and clothes respectively. It's a real bedroom, aspiring to be a control room... :lol:

Soundman2020 wrote:Source of the post 1) SBIR: the speakers are too far away from the front wall.

Soundman2020 wrote:Source of the post 2) Vibrations

Soundman2020 wrote:Source of the post 3) "Early-early sound"

Soundman2020 wrote:Source of the post 4) Reflections.

Soundman2020 wrote:Source of the post 5) Comb filtering.

I am aware of all these issues you display, but I appreciate that you took the time to analyze them in such detail. The graphs and the tables you cite are very valuable, indeed!. (For instance, the Neumann table can be really handy for having an idea of how the sbir frequency is pushed upwards the closer the source (speaker) gets to the boundary! Thanks for sharing!.
Regarding the "1" in conjunction to "5" and "4" you guessed right that I preferred to avoid desk reflection comb filtering at the cost of a lower sbir frequency. Getting a new desk is rather impossible at the moment since I am tight on budget already. The cloud insulation alone + a few extra boards (18 boards in total) costed €100 while the rest (40 boards of b030) costed €73. These prices are just fine for the products of course, but if you add the lumber I used (€95) and the fabric which I haven't got yet the budget goes up quite a bit.

Thus regarding the separate speaker stands I am afraid it is impossible due to lack of space, despite owning a pair which I can't use.
But I'm curious about the "speaker surrounding" sbir panel you recommended. I'd be glad If you shared any pictures of this. :)

The nearfield pressure fluctuation is something I wasn't aware of. My sweet spot is roughly 1.2m away from each speaker, so that is not too close, but unfortunately that is the longest I can get. Maybe I could push the speakers 7cm further towards the sbir panel, but no more than that is possible, due to xlr/power cables on the back and angle towards the sweet spot.

Soundman2020 wrote:Source of the post You already have desk reflections, vibrations, and comb-filtering....

The way I have my setup I suppose I have diminished the desk reflections which only come from the small keyboard desk and not from the speaker desk. But probably that is not enough to fully eliminate them.

Soundman2020 wrote:Source of the post As above: I would create a sort of "C" shaped panel, where the speaker is in the middle of the "C", surrounded on three sides by the absorption, with the rear corner of the speaker almost touching the wall (or window! ).

As I mentioned before, I am having trouble understanding it. I mean I get the "either side of the desk" panels placement, but which one is the third size of absorption? Maybe I misunderstood your description but you mean the back of the speakers are almost touching the wall, right?

Soundman2020 wrote:Source of the post So you would need to to do some testing to find out what frequency range you are losing too much of, then add the right thickness plastic accordingly. However, you cannot do that on your first reflection point absorbers! Only on your bass traps and SBIR treatment.

Yes I understand. It makes sense that it shouldn't create directional (high frequency) first reflection to the sweet spot . Thanks for noting!

Soundman2020 wrote:Source of the post Generally, for small rooms like yours I recommend using an "angled, hard-backed ceiling cloud", over the area between the speakers and the listening position. The angle and hard back help to redirect some of the sound towards the rear wall, where it can be absorbed more, and can also be beneficial for vertical modal problems.

So that's why I see some angled models in some rooms. I thought it was just for coercing the first reflection sound beam to travel a longer distance into the insulation,thus being more absorbed.I never thought these would be hard backed.Thanks for the enlightenment! :D
In my case it wouldn't be beneficial though, since there is no room for decent absorption that behind me. I am only planning to put a board of insulation just as a slight high frequency reflection treatment (no gap behind it).

Soundman2020 wrote:Source of the post Sorry about that! I also added some new anti-spam features to the forum. I'm trying to improve it all the time. If it happens again, please send me a PM (Private Message), as I will probably see that sooner than a comment in a thread.

No need to apologize! I will send PM if it happens again!

I would like to thank you again for your will and time to assist me! I am really sorry that I can't do much of what you propose at the current time, but I definitely keep everything in mind for future improvements. I will come back with a few photos of the process!




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