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Huge hole in upper bass response - Suggestions?

mattzildjian

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Oct 17, 2020
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Hi all,

I have a simple setup of a Wiim Amp + Elac DBR62's which looks like this

IMG_20241227_204157.jpg


The sofa at the bottom of the image is the MLP.

Unfortunately, at this listening position, there is a huge hole in the upper bass response and this is very noticeable, making a hollow sound especially in vocals. The issue is most apparant when watching TV / Movies since the dialogue can almost disappear entirely if it falls within this dipped area making for a frustrating experience often being unable to hear what people are saying.

Here is the response from the Left speaker

Left Speaker no EQ.png


And the Right Speaker

Right Speaker no EQ.png


Is this due to SBIR? or something else? I have moved the speakers all around within reason and I cannot fully remove this dip, this is the best response I could get.
I have seen many recommendations for avoiding SBIR to place the speakers as close to the wall as possible, I have tried this and the dip was just moved up slightly, and the overall response was much worse.

As you can see the room is carpetted, I have curtains and 2 sofas, however most hard walls are bare. Would treatment help? Any suggestions on a budget that arent eye sores?

As of right now I am filling the hole with additive EQ which I usually avoid, but it is helping.

Thanks in advance!
 
This may help you: https://www.bobhodas.com/sound-advice-1.php

Personally, I've never heard a good setup where the speakers are close to the front wall and the listening position is close to the back wall, because the listener is sitting in a mirror-image of the wall null. Instead, I've always relied on the Rule of Thirds. There is another rule of thumb, called the Rule of Fifths.


In short, IME fashionably acceptable placement of speakers and furniture have never resulted in good sound. All the good-sounding installations I have heard have put acoustics first, and fashion be damned. That's why they've all been dedicated listening rooms.
;)
 
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If you've already tried all options available to you with regards to speaker position and seating position, you're probably pretty much stuck with this response. If you can accept a large acoustic panel at least 4 inches thick behind each speaker, that might help a little bit, but the dip will not disappear entirely.

Not that it helps, but dips like this is very common in the 100-300hz area - nothing unique to your room or setup.
 
Hi all,

I have a simple setup of a Wiim Amp + Elac DBR62's which looks like this

View attachment 416927

The sofa at the bottom of the image is the MLP.

Unfortunately, at this listening position, there is a huge hole in the upper bass response and this is very noticeable, making a hollow sound especially in vocals. The issue is most apparant when watching TV / Movies since the dialogue can almost disappear entirely if it falls within this dipped area making for a frustrating experience often being unable to hear what people are saying.

Here is the response from the Left speaker

View attachment 416928

And the Right Speaker

View attachment 416929

Is this due to SBIR? or something else? I have moved the speakers all around within reason and I cannot fully remove this dip, this is the best response I could get.
I have seen many recommendations for avoiding SBIR to place the speakers as close to the wall as possible, I have tried this and the dip was just moved up slightly, and the overall response was much worse.

As you can see the room is carpetted, I have curtains and 2 sofas, however most hard walls are bare. Would treatment help? Any suggestions on a budget that arent eye sores?

As of right now I am filling the hole with additive EQ which I usually avoid, but it is helping.

Thanks in advance!
Probably placing your speakers more towards MLP to push this dip into the 60-80Hz region and adding subwoofer would help.
 
In addition what has been suggested, you could try to mitigate the SBIR effect with a cheap 'subwoofer' on the floor against the front wall that has >200Hz response and a phase knob. I don't think Wiim's bass management has a correct way to integrate this solution, so you have to use speaker level inputs (that's why a continuously variable phase knob is essential - ie. Jamo SUB210). That way you have many spatially distributed sources interacting in the upper-modal/SBIR region. Think of it as an Allisson-style speaker placement.
 
What are room dimensions and listener position from the front wall? You can check the room sim in Room EQ Wizard and see if the simulated response is similar, then make the adjustments (speaker/listener placement, more absorption). By the way, I have the same speakers (including the color) and they look so tiny in your picture that I didn't recognize them until I read :)
 
Try to move the speakers closer to the sidewalls, this helped me in a similar situation. Even a few cm difference can help.
 
Thanks for all the suggestions, I will try moving the speakers a little closer to the MLP and a little further apart and see how that measures and report back.

Can anyone suggest an acoustic panel option to put behind the speakers that might help and isnt too expensive? thanks!
 
I have seen many recommendations for avoiding SBIR to place the speakers as close to the wall as possible, I have tried this and the dip was just moved up slightly, and the overall response was much worse.
It is called SBIR (speaker boundary interference response), but it concerns the listening position too. If you move the speakers close to the wall and the dip more or less stays, then this is probably due to the fact that the dip is actually two dips more or less in the same place. One from speaker in front of wall and the other from listener in front of wall.
[ Edit: It is even more complicated, as there are effects from the side walls too. You can check out with Room sim tool in REW.]
Have you measured with the microphone at a different distance from back wall?
Whether you want to change your listening position is another question.
 
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Thanks for all the suggestions, I will try moving the speakers a little closer to the MLP and a little further apart and see how that measures and report back.

Can anyone suggest an acoustic panel option to put behind the speakers that might help and isnt too expensive? thanks!
My DIY panels are made of 2 inch Rockwool

In my small room, I find that seating position, and toe-in is the first place to start experimenting.
 
I did some measurements at different positions.

Left Speaker
Blue = Positioned as pictured in OP
Orange = Pushed back against the wall
Red = Pulled forward an extra foot (2 feet from the back of the wall to the back of the speaker)
Left Speaker Placement Comparison.png


Right Speaker
Yellow = Positioned as pictured in OP
Light Blue = Pushed back against the wall
Pink = Pulled forward an extra foot (2 feet from the back of the wall to the back of the speaker)
Right Speaker Placement Comparison.png


The right speaker response is so much worse than the left.
 
Putting in an absorber like this (Link) in each corner may help, so that a part of the first reflections is mitigated. Or even better an absorber on the ceiling. Lowering reverb makes the sound more precise and will let your the room in the recording better.
 
IME there is always a big dip in that 100-300 region. Shifting speaker position will just shift the dip. I have learned to live with it after positioning my speakers for the narrowest dip (doesn’t matter if it is very deep), somehow my brain doesn’t really hear a narrow but deep dip.
 
test the speakers outside do REW sweeps see how they appear may give you idea , take pictures or video of the test
 
If it’s possible for you to move the speakers a foot or two further out in the room than you did in the red/pink measurements, the dip will probably move down under 100 Hz and that should make it possible to add a subwoofer or two to your system to solve the problem.
 
If it’s possible for you to move the speakers a foot or two further out in the room than you did in the red/pink measurements, the dip will probably move down under 100 Hz and that should make it possible to add a subwoofer or two to your system to solve the problem.
This would be my choice too.
 
If it’s possible for you to move the speakers a foot or two further out in the room than you did in the red/pink measurements, the dip will probably move down under 100 Hz and that should make it possible to add a subwoofer or two to your system to solve the problem.
If I pulled them out further they would be in the middle of the room, it's just not practical at that point, they were already too far into the room at the time of the measurements for pink / red. The room may appear bigger in the picture due to the wide angle lens I used to get most of it in one shot. Here are the measurements:

dimensions floor.png
 
Oh… one more thing i forgot to share. Don’t just rely on frequency sweeps only. Please also do a MMM RTA measurement around your listening position to compare. The dip might not be that bad.
 
test the speakers outside do REW sweeps see how they appear may give you idea , take pictures or video of the test
Not sure if I am willing to go as far as taking outdoor measurements just yet, but I was curious about whether the wiim amp was just lacking power to drive the DBR62's correctly so I did do some close measurements of the woofer.

Close measurements (woofer)
Orange = Left Speaker
Purple = Right Speaker
Close Woofer.png


Oh… one more thing i forgot to share. Don’t just rely on frequency sweeps only. Please also do a MMM RTA measurement around your listening position to compare. The dip might not be that bad.
All of my measurements are RTA and they are an average across a 2 seat sofa.
 
actually move the speaker around the room steadily with generated pink noise keep the averages 8 or 16 thou better get someone assist to move the speaker around while watching the RTA until you find best location within the width of the wooden cabinet for the tv get the idea ?
by the way like to see more pictures of you'r cat
 
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