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Massive bass reverberation

ppataki

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@Matias

This is what your measurements look like when using var smoothing:

View attachment 231495

No wonder it sounds boomy still, don´t you think? I suggest using var smoothing and higher Q-values for bass EQ and focus on reducing the most offensive peaks. Those are still very high after your current EQ. Also, i think you pushed the upper bass too hard with EQ and i highly recommend trying better positions for your speakers and/or listening position. I would focus on smoothing out the 70-300Hz region first with better positions, as good as it gets. Then cutting the peaks with EQ. At last tuning the treble to taste with low Q filters.
That is why I created the convolution filter for the OP - to flatten the FR
I hope @Matias will give it a try; IMHO it shall help a lot (even if an additional low shelf is applied)
 

Curvature

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I would also say that it's normal to notice boom after installing broadband absorption. Which is why most of the products offered by acoustical companies effectively obfuscate the issues instead of really helping.
 
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Matias

Matias

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That is why I created the convolution filter for the OP - to flatten the FR
I hope @Matias will give it a try; IMHO it shall help a lot (even if an additional low shelf is applied)
I will give it a try. As well as creating myself new EQ filters using var smoothing too. Let's see if this helps.
 
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Matias

Matias

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Also, i think you pushed the upper bass too hard with EQ and i highly recommend trying better positions for your speakers and/or listening position.
If I were pushing higher SPL on the low limit of the drivers, 32 Hz and 300 Hz for woofer and mid, then the excessive excursion could potentially damage them. But I thought it safe to push the upper range of the woofers since this is a low excursion range. Don't you think?

But point taken on the psychoacoustic versus var smoothing. I will definitely give it a try.

As for positioning, I put the speakers quite away from the front wall to reduce the 40 Hz mode (played around with the REW room simulator moving the speaker around and checking the predicted modes). This current position is roughly an equilateral triangle of 2.4m between speakers and the recliner chair, on axis.
 

dasdoing

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here is my backwall absorber. 70cm deep. full of that fluffy stuff you see on the top. yes, it takes a lot of space, but it massivly cured the first room mode

UPZcdeADsDlnl0hpf9nexejsNC7qcOIP1F3Saj1oxztMcnKXN_YqgW7mimrlLNP095lGP-gm6wEvUDZaZ3xiUXZ5qiRCrEjhJOnLxFYZX7J-00N_uIcnyGI9-9P6oohMnQRAbHjsxIcym_0rLUvPyab4tKbXu2oeyFp5hyVTg23OjV8xE2oDmBV7pqPHuOQZHXOx-Tf59DTpoZduCYqzdXo_mrqGD4AEiXaKPachD9JiuelnOw2a1arFutb0qI_fcWzrmhZ8fQpHDnOGU9xI0hE8bzPw9yJV6v6erKWc5sApgaJzwnZMsgu5FTeunMBwf1cwR_n_idjJIPLYXBoxgMWHrVc_zpT50XXwRXrq9hyRFV8ofjrQADw96KGCO2vKdh362dpG6YjPLceKPJGsZksYlMNc--iJso6sm6kyPayfBwu4p2YhFnI8P3NiBANEs_BhwxPyn1jdCi4rjSDBVlTji0yaSCF2Ywv5f7lNNll6pQnXJ_69UjsjuT7N1YIi5_9OuH2MNEg14aXG-oKZHiIJIWDB_e_YzQfVoPtzDXMXoJLv7XYVpJHp_cy95byzW3iSHznv8UJL6m0KDaO_m5KFnB3JwA7GPwekz0w_xY5mdd3DmP3M3CicxY-vH4K8FFH-AYhZ_8p135uc8C4gvnehtPceUd6PVEB3x88jUoXEGkgplPSxhaLgG6ai1vYIcf-2n620p7D9i6u9sGsF-fFZfExcWYgRjcb7nHhEWiA90yldkF4b6sFmTso=w2700-h2024-no
 

raindance

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In this situation I've sometimes been able to solve it by using SBIR to my advantage and placing my speakers the appropriate distance from the front wall to achieve SBIR cancellation of the major bass mode in my room. It's also important to have the distance to the side walls different from the distance to the front wall to avoid boom. This puts them fairly far into the room, but it looks like you'd be ok with this. In my situation it removed the bass peak and the decay time at that frequency became very short as well.

Also, for an optimized room, the picture makes it look somewhat square, which would make achieving good bass very challenging.
 

DjBonoBobo

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If I were pushing higher SPL on the low limit of the drivers, 32 Hz and 300 Hz for woofer and mid, then the excessive excursion could potentially damage them. But I thought it safe to push the upper range of the woofers since this is a low excursion range. Don't you think?
I have no technical answer, it is just that from my experience and from what i´ve read i would try reducing the dips in the upper bass by positioning and use only little EQ-boosting in this region. I don´t know what´s safe and what is not for your speakers. I never thought about this because my speakers have limiters.

As for positioning, I put the speakers quite away from the front wall to reduce the 40 Hz mode (played around with the REW room simulator moving the speaker around and checking the predicted modes).
From my experience, you can very easily flatten a 40Hz peak with EQ. The range between 70-300Hz is much harder to deal with EQ, and also much more important for the subjective listening experience. That´s why i would focus on optimizing this range first instead of deep bass.
 
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Matias

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I have no technical answer, it is just that from my experience and from what i´ve read i would try reducing the dips in the upper bass by positioning and use only little EQ-boosting in this region. I don´t know what´s safe and what is not for your speakers. I never thought about this because my speakers have limiters.
This reminds me a of a post from Lars showing Purifi drivers and the excursion limited SPL. Not that my speaker uses Purifi woofers, but I suppose it applies to all drivers.

purifi excursion limited SPL.jpg
 

DjBonoBobo

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Matias

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That is why I created the convolution filter for the OP - to flatten the FR
I am looking at your mdat, and it is flat in the MLP, while my personal preference is a slope of -0.8 dB/octave. I export my filters in a stereo wav file and use JRiver's convolution DSP to process it during playback.
 

ppataki

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I am looking at your mdat, and it is flat in the MLP, while my personal preference is a slope of -0.8 dB/octave. I export my filters in a stereo wav file and use JRiver's convolution DSP to process it during playback.
You can either use that slope in REW when you generate your filters or you can leave it flat and apply shelf filters downstream post the convolver
I prefer the latter but it is up to taste I guess
 

goat76

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First, I think you should use the following room mode calculator to find out where the problems/room modes are located in your room. It's called Amroc "The RoomMode Calculator". Just write in your room dimensions and then look at the Room 3D graph where the 40Hz and 51Hz (and maybe the 90Hz and 100Hz as well) problems occur which can clearly be seen in your measurements if you look at your waterfall diagram below: https://amcoustics.com/tools/amroc

Matias Waterfall.jpg


It's not easy to fix these room modes but I think the best solution is corner bass traps specifically aimed at the problem frequencies. I have similar problems in my listening room but have yet not found any solutions that suit a regular living room without making it look like a studio. :)



I know you said that your aim is at fixing the lower bass problems, but when looking at your RT60 Decay graph it seems like you may have applied uneven broadband absorption to the room, and I think you should try to fix the decay times from 1kHz and up, and maybe from 350Hz and down as well but that doesn't look too critical.
As I understand it the line in the lower window should be as straight as possible, but under 100Hz it's no problem if it goes up to double the decay time.

Matias RT60 Decay.jpg


Down below is a video from Audioholics if you want to explore how the "RT60 Dekay" should be done.



And this video which is from Audioholics again is a good watch. Anthony Grimani got a lot of good information on room acoustic treatment.

 
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bo_knows

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Hello Matias,

Congratulation on the room! It looks great!

As far as the bass issues in 50-40Hz, you are not alone. I have a dip in the 50Hz range and still trying to figure out how to deal with it with passive treatments alone. I was able to do it with one subwoofer and Denon Audyssey phone app but prefer to listen to my 2 channel music without the sub and any DSP.
I would suggest you explore the option of using the MLV material. You may be able to alter your existing panels and add MVL on the back with a 2-inch distance from the insulation material.

Here is some testing done on it.




My room response 20-200Hz no smothing.

20-200Hz no smoothing.jpg


Good luck!
 
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