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

Bjorn

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A weakness with the multiple subwoofer approach is that it doesn't do anything above a certain frequency and those resonances are very audible. If those aren't treated, you end up with mediocre result no matter how flat the sub frequencies are. Quality treatment on the other hand will address that area too. Another potential issue with multiple subwoofers is seamless integration. Not saying it isn't possible, but it's definetly a challenge with far spaced sources.

For me it isn't either multiple subwoofer or treatment. Treatment is necessary for a well time domain behaviour and which is essential for a good result. Multiple subwoofers can be a solution do address especially cancellations if placement and treatment isn't sufficient. Both have their place.

Corner placement of subwoofers can work very well and you pick up sensitivity from boundary gain. Here's the response of one corner placed sub without any EQ.
freq response subwoofer corner placement.jpg
 

Bjorn

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Duke

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A study on something that doesn't exist in a small room. How intriguing!
I haven't finished reading the paper yet, but I do not get the impression that it is about something which does not exist in a small room.

Correct me if I'm wrong, but I think you are objecting to the use of term "reverberation" in the context of small rooms (i.e. home-audio-size rooms). I think this is because "reverberation" implies a uniform field of reflected energy, which does not exist in small rooms; rather, each location in a small room is subject to a finite number of discrete reflections, one implication being that the placement of acoustic treatment (relative to sources and listeners) in a small room is critical, which is not the case in a large room which has a statistical reverberant field.

I think that many people who use the term "reverberant" or "reverberation" in the context of small rooms are aware of this, but those words are an easy way to communicate the idea of "all of the reflections in a (small) room, which die away over time", even if they fall short of absolute precision.

Assuming I'm not too far off base, do you have an alternative to the word "reverberation" which you use in the context of small rooms?
 

patate91

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I haven't finished reading the paper yet, but I do not get the impression that it is about something which does not exist in a small room.

Correct me if I'm wrong, but I think you are objecting to the use of term "reverberation" in the context of small rooms (i.e. home-audio-size rooms). I think this is because "reverberation" implies a uniform field of reflected energy, which does not exist in small rooms; rather, each location in a small room is subject to a finite number of discrete reflections, one implication being that the placement of acoustic treatment (relative to sources and listeners) in a small room is critical, which is not the case in a large room which has a statistical reverberant field.

I think that many people who use the term "reverberant" or "reverberation" in the context of small rooms are aware of this, but those words are an easy way to communicate the idea of "all of the reflections in a (small) room, which die away over time", even if they fall short of absolute precision.

Assuming I'm not too far off base, do you have an alternative to the word "reverberation" which you use in the context of small rooms?
Maybe decay time is better.
 
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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.
if we're talkin smack up against the walls of a corner, then yeah, corner placement is bad. however, corner placement in general is a very good thing in my installation. moving it a 1-2 feet from the side wall and at least 8 to 12" from the back wall alleviates many peak related issues as I have confirmed by measurements many times over.
as far as mini dsp is concerned i have never found a need- my response becomes very smooth as measured at the listening position by just using the subwoofer controls and fine tuning placement.
 

Chromatischism

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if we're talkin smack up against the walls of a corner, then yeah, corner placement is bad. however, corner placement in general is a very good thing in my installation. moving it a 1-2 feet from the side wall and at least 8 to 12" from the back wall alleviates many peak related issues as I have confirmed by measurements many times over.
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?
 
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stevenswall

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Thread Starter #109
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?
How is midwall the best? Won't sound hit the side walls and you'll get a null at various frequencies depending on where you're sitting along the center line?

If midwall is the best I should be getting a subwoofer I can place my TV on.
 
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How is midwall the best? Won't sound hit the side walls and you'll get a null at various frequencies depending on where you're sitting along the center line?

If midwall is the best I should be getting a subwoofer I can place my TV on.
It's hard to say. Many factors will influence the bass response. For example, if you place the sub under TV and sit 5 feet from rear wall, you'll probably see a massive null at 60hz. For my setup, the best spot for single sub is in the middle of the room.
 

Duke

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How is midwall the best? Won't sound hit the side walls and you'll get a null at various frequencies depending on where you're sitting along the center line?
Todd Welti of Harman wrote a white paper entitled "Subwoofers: Optimum Number and Locations" which makes several recommendations, including center-of-the-wall. You can skip ahead to his Conclusions starting on page 28, then go back and read how he came to his conclusions if you want.
 

Chromatischism

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How is midwall the best? Won't sound hit the side walls and you'll get a null at various frequencies depending on where you're sitting along the center line?

If midwall is the best I should be getting a subwoofer I can place my TV on.
Technically, that would give smoother bass response :)
 

Chromatischism

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It's hard to say. Many factors will influence the bass response. For example, if you place the sub under TV and sit 5 feet from rear wall, you'll probably see a massive null at 60hz. For my setup, the best spot for single sub is in the middle of the room.
Don't sit in the length mode.
 

Kal Rubinson

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Todd Welti of Harman wrote a white paper entitled "Subwoofers: Optimum Number and Locations" which makes several recommendations, including center-of-the-wall. You can skip ahead to his Conclusions starting on page 28, then go back and read how he came to his conclusions if you want.
Tangential comment: Welti says, at the beginning, "We are interested in acoustical response in a seating area, not at one particular seat." Some of us, however, are interested in optimizing the sound/bass for one particular seat (or two) and, so our goals are not the same.
 

win

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Where are these magical listening rooms that are perfectly rectangular sealed enclosures I read so much about?
 

Lbstyling

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Where are these magical listening rooms that are perfectly rectangular sealed enclosures I read so much about?
This is why Geddes method works. It's practical and fairly simple.

I believe there is also a free programme you can download (on AVS?) That you draw your room dimensions in and it calculates the response.
 

Duke

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Tangential comment: Welti says, at the beginning, "We are interested in acoustical response in a seating area, not at one particular seat." Some of us, however, are interested in optimizing the sound/bass for one particular seat (or two) and, so our goals are not the same.
The end result of multi sub is both flatter response at one seat and at multiple seats. Both goals are attained.
^^What he said.^^

The goal of "optimizing the sound/bass for one particular seat (or two)" is imo well served by multiple subs, and they can be correspondingly smaller. Even with EQ, there is an improvement in smoothness with multiple subs.

Of course you already know this; you compared one JL Audio Fathom 110 vs three JL Audio Fathom 110's. By the way, you were spot-on with your insights and explanations again and again in your review, and your positioning of the three subs was excellent in my opinion. I say this having been a distributed multi-sub system manufacturer for the past fourteen years.

The only thing I can think of offhand that might have further improved the in-room smoothness would have been reversing the polarity of the sub in the right-rear corner, or otherwise significantly altering its phase relative to the other two. This which might call for its gain to be adjusted relative to the others to optimize smoothing, and for the net gain of all three to be increased to restore correct tonal balance because the reversed-polarity sub will increase the in-room partial cancellation, which is the trade-off for the increased smoothness.

To be sure. However, there might differences in how one optimizes for one or the other.
As far as EQ goes, YES. The smaller the physical area you wish to optimize for, the more effective EQ can be within that area.

And even with multiple subs, the subwoofer locations could be optimized for a single sweet spot seat, for those with sufficient placement flexibility. Do the subwoofer crawl to place the first sub. With the first sub positioned and active, do the crawl for the second sub. Rinse and repeat. Probably would want to downward-adjust the gain of the active subs in between crawls.

There is a distributed multi-sub set-up technique which increases the sense of immersion in a large acoustic space. It calls for an even number of subs... with apologies to George Orwell, "two subs good, four subs better." Anyway let me know if you'd like details.

Where are these magical listening rooms that are perfectly rectangular sealed enclosures I read so much about?
The VERY BEST rectangular rooms have no "soft spots" in the room boundaries. That means no doors, no windows, no air circulation ducts, no openings of any kind. Unfortunately listening time is limited by the amount of oxygen in the room.

But the bass is to die for.
 
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Chromatischism

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Where are these magical listening rooms that are perfectly rectangular sealed enclosures I read so much about?
Spare bedrooms are great. The next time you move, look specifically for a place where you can see your system. I prefer to keep it out of the "living room" which is nothing but compromises and unhappiness.
 
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