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Never Put Subwoofers In Corners... Even with DSP and Multi-Sub Setups?

Trdat

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I'm not sure that what is happening here is what you think is happening. All small, DSP-enabled sealed subs today come with EQ applied from the factory to give the magic low end extension that would otherwise be impossible in a small, sealed configuration. Done correctly, this does nothing to destroy or diminish transient response.

According to other experts this is the consensus both on the techtalk and DIY forums, with most not all people who have participated in this discussion. But like i said, I didn't agree with it at first either and keen to get other opinions from this forum, as I do have many questions that relate to this. After speaking with many experts there is still confusion and disagreement with transients in lower frequencies. I have even been told that group delay doesn't have much to do with the transient response which is contrary to what we are usually told.

You also seem to imply that EQ can't be applied to sealed subs to even out room modes without somehow making it sound worse(?), which also isn't true
.

Definitely not implying this.

All I am implying is that when I apply parametric EQ or some other convolution my perfectly toned, low QTC, thumping, slamming, fast paced transient subs are not the same. If room modes have improved it doesn't bother me cause Im left with overhang from the bass that i never had without the EQ.
 

Chromatischism

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All I am implying is that when I apply parametric EQ or some other convolution my perfectly toned, low QTC, thumping, slamming, fast paced transient subs are not the same. If room modes have improved it doesn't bother me cause Im left with overhang from the bass that i never had without the EQ.
What sub? Maybe it has difficulty handling the EQ.
 

Chromatischism

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Thats tight. And you didn't feel a difference, interesting.

I know for a fact that there has been blind tests on similar EQ'd roll offs on different subs and no one was able to tell the difference. But, I have to find them as I was told about it and never went searching.

That said, when I experimented I usually do these tests at loud volumes perhaps the driver was overshooting. But I am convinced that the transients was totally lost once a convolution was in play.
Well, what I mean is that it always sounds better to me with lower extension. The weight that anchors the presentation is really nice. But the masking effect is real (psychoacoustics) and if you want to emphasize mid-bass detail, you don't want huge low end. I just don't prefer that as it sounds too lean to me.
 

Trdat

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ernestcarl

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...when I apply parametric EQ or some other convolution my perfectly toned, low QTC, thumping, slamming, fast paced transient subs are not the same. If room modes have improved it doesn't bother me cause Im left with overhang from the bass that i never had without the EQ.

People's mileage vary... but I would try to avoid generalizing.

As for me, without any parametric EQ, my sub and speakers' bass is somewhat of a wreck.

I highly suspect the type of EQ or DSP settings you're using is causing this apparent bass 'overhang' or transient delay. Maybe it's specific to your setup.

I've been experimenting a bit with my filters for my couch setup and this is the best I have been able to achieve, so far...
1598643392504.png

sub cut-off is 10Hz 48dB/oct.

That spike in delay around 125Hz is caused by sidewall reflections -- nothing can be done on that front.

That hump around 70Hz is partly due to my ported speakers' natural bass phase/time delay/roll-off, and also due to my steep LR8 (48dB/oct) xo.

There is some cancellation, but only in the left speaker -- there's an open hallway directly behind the right speaker which mitigates the situation.
1598644071516.png


You can see it with the filtered impulse view
1598644202531.png


1598644272240.png

between 34-36ms

Also quiet visible in the spectograms
1598644470049.png


Though probably clearer with the wavelet
1598644516560.png


Now, without any PEQs 300Hz down
1598645347642.png

Significantly worse under 30Hz above

Significantly worse under 40Hz below
1598645460916.png


1598645648580.gif


From my experience, at least, PEQs is a must regardless of the type of media being played.
 

avanti1960

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That's because you're exciting the room modes less by not using the corner effectively. Corner placement usually only works well with multiple subs.

The best place is mid-wall: have you tried that?
mid wall placement reduces the output considerably. many subs recommend corner placement - the key is to move it left / right / in / out to get the smoothest response whether multiple or single subs.
 

Chromatischism

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mid wall placement reduces the output considerably. many subs recommend corner placement - the key is to move it left / right / in / out to get the smoothest response whether multiple or single subs.
That hasn't been my experience. I've always been able to hit the max SPL of my subs with mid-wall placement.

Corner placement tends to not give the best response with 1 or 2 subs, but apparently does if you can occupy all 4.
 

Duke

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Corner placement tends to not give the best response with 1 or 2 subs, but apparently does if you can occupy all 4.

In my experience (manufacturing a four-sub system since 2006), one sub in each corner is far from being the best response one can get from four subs. Ime there are other placement strategies which yield considerably smoother results, and "smooth bass" = "fast bass".
 

ferrellms

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This article seems to go against a lot of what I hear on the forum: (Is this guy just trying to sell something?)

https://www.acousticfields.com/why-you-should-never-place-subwoofers-in-your-corners/

"So don’t buy into this culture of putting the subwoofer in the corner. And definitely don’t buy into the culture of multiple subs will smooth out the frequency response. Yes, technically it will but the smoothness, the level of smoothness that you get in the bump is so minuscule, it’s maybe 1 or 2 dB."

Pretty sure it's going to sum and be +3dB or -3dB, plus a MiniDSP should be able to help even more.

Also, if it's just adding a bunch of gain putting it in the corner, DSP would fix that too it seems: I have my Genelec's in a corner and they measure flat down to 18hz or so.

I remember another user who said that it's all about controlling the peaks and nulls in the room, and even ringing and smear can be controlled just by having a DSP system take care of the peaks, which goes against what this guy says about treatment:

"Put that money in treatment. You’ll be way better off. Use less energy, more treatment and balance it out that way. It’s better to reduce the response."

Looking at getting a pair of Rythmik FV15 subwoofers to use as stands once I move everything to the basement, but apparently corner placement is bad even if I run things from a MiniDSP.

Also of Note: Speakers that go low enough not to "need" subwoofers... Just make me want subwoofers more because now I know what things can sounds like and sometimes want it louder when watching Interstellar.
You should put the first subwoofer on the floor in the corner. Putting it on the floor in the corner will activate the most room modes and bring the subwoofer level up. This set up will provide the most dynamic range and the fewest nulls, but may be peaky. Measure and EQ down the peaks. You can EQ peaks down, but cannot EQ nulls up.

A fellow named Tom Nousaine dragged a subwoofer to the homes of several of his friends and measured each room several times with different subwoofer locations (before EQ). Even without EQ, corner on the floor placement was the smoothest and loudest in every single listening room.
 
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Chromatischism

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You should put the first subwoofer on the floor in the corner. Putting it on the floor in the corner will activate the most room modes and bring the subwoofer level up. This set up will provide the most dynamic range and the fewest nulls, but may be peaky. Measure and EQ down the peaks. You can EQ peaks down, but cannot EQ nulls up.

A fellow named Tom Nousaine dragged a subwoofer to the homes of several of his friends and measured each room several times with different subwoofer locations (before EQ). Even without EQ, corner on the floor placement was the smoothest and loudest in every single listening room.
That is contrary to others' findings, such as Todd Welti and Floyd Toole.

Putting a subwoofer in a corner will raise its level, but not evenly. EQ will be required to smooth it out. Even still, most often mid-wall placement gets smoother results. Of course every person needs to experiment in their own room.
 

RichB

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That is contrary to others' findings, such as Todd Welti and Floyd Toole.

Putting a subwoofer in a corner will raise its level, but not evenly. EQ will be required to smooth it out. Even still, most often mid-wall placement gets smoother results. Of course every person needs to experiment in their own room.

I believe Floyd Toole once described as corner loaded subs as free bass, equalization was implied.

- Rich
 

bobbooo

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You should put the first subwoofer on the floor in the corner. Putting it on the floor in the corner will activate the most room modes and bring the subwoofer level up. This set up will provide the most dynamic range and the fewest nulls, but may be peaky. Measure and EQ down the peaks. You can EQ peaks down, but cannot EQ nulls up.

A fellow named Tom Nousaine dragged a subwoofer to the homes of several of his friends and measured each room several times with different subwoofer locations (before EQ). Even without EQ, corner on the floor placement was the smoothest and loudest in every single listening room.

According to Floyd Toole's book, the nulls will be about the same (some deeper) with a single sub in the corner compared to mid-wall, as well as exciting more modes (peakier response):

20200920_171439.png


Describing the above graph, Toole says:
Figure 13.13a shows that a single subwoofer in a corner energizes all of the horizontal-plane modes in the room. Moving the single subwoofer from the corner to a midwall position does precisely what was predicted in Figure 13.11b: The first-order width mode (0,1,0) at 28 Hz has been eliminated because the subwoofer is located at a pressure minimum.
 

sigbergaudio

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I find that many of the subwoofer placement recommendations assume you have no DSP or EQ available. When you do, placement recommendations becomes a little less clear cut, and more positions can work well. After all, most people will have a limited choice as to where to position their subwoofer - so while it can be useful to know what mostly works, a compromise must normally be made despite general recommendations. Luckily, EQ can do quite a bit these days.
 
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ferrellms

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I find that many of the subwoofer placement recommendations assume you have no DSP or EQ available. When you do, placement recommendations becomes a little less clear cut, and more positions can work well. After all, most people will have a limited choice as to where to position their subwoofer - so while it can be useful to know what mostly works, a compromise must normally be made despite general recommendations. Luckily, EQ can do quite a bit these days.
The recommendation on corner placement does not assume anything about EQ. But EQ works best with corner placement. EQ cannot fix deep dips or nulls. Luckily, those are less noticeable than peaks. But, if placement can reduce the number of deep dips in the first place, such as corner placement will, it will result in flatter frequency response and more dynamic range after EQ. Obviously, if you can't put the subwoofer there, you need to find another place. But if you can, do it.[/QUOTE]
 
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ferrellms

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According to Floyd Toole's book, the nulls will be about the same (some deeper) with a single sub in the corner compared to mid-wall, as well as exciting more modes (peakier response):

View attachment 83922

Describing the above graph, Toole says:
Interesting. It looks like both can be EQed to be pretty flat. I like the corner placement due to the much better dynamic range (nearly 20 db!) in the low bass. That mode down low is activated resulting in better dynamics after EQ.

Mid-wall is also a good choice and often more convenient and attractive to look at.
 
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RichB

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Here is a short summary of subwoofer placement from Audioholics:


At about 7 minutes, he discusses the advantages of corner placement.

- Rich
 

Chromatischism

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Here is a short summary of subwoofer placement from Audioholics:

At about 7 minutes, he discusses the advantages of corner placement.
*When using all 4 corners.

It's worth noting that mid-wall is generally best for 1-2 subs, and corners tend to come into their own if you can use all of them. Maybe in the future in a bigger room I can try that.
 

RichB

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*When using all 4 corners.

It's worth noting that mid-wall is generally best for 1-2 subs, and corners tend to come into their own if you can use all of them. Maybe in the future in a bigger room I can try that.

In my room, there are two corners up front and maybe room for a center back.
Any decision is based on constraints, measurements, and EQ options.

- Rich
 

zym1010

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update: realized I made a mistake in my experiment, by putting the subwoofer's reflex port too close to the wall. So my findings might not hold. In any case, I probably won't use the corner setup, as it's too far away from the center and makes too much sound coming from one side (but that's a separate discussion)/

------------------

I just tried placing my Genelec 7350A in the corner compared to its original location (center, slightly the to the right). The frequency response after GLM correction got slightly better compared to the original location, but the boominess is too strong (in other words, the bass is not tight). So I personally don't recommend it, for music listening at least.
 
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Wayne A. Pflughaupt

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Sure, you’ll usually get a modal peak with the sub in a corner. Parametric EQ can easily fix that – it’s been the go-to remedy on the home theater forums for more than 20 years now. I’ve had corner subs in three different homes, and every one worked great after EQ. My current place, it couldn’t happen, and guess what? Now I have a nasty null. EQ can’t fix that.

Regards,
Wayne A. Pflughaupt
 
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