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post #7621 of 9372
Quote:
Originally Posted by Bill Fitzmaurice View Post

+1. Fluid dynamics are useful when examining the behavior of an acoustic wave of a single wavelength. But since we don't listen to acoustic waves of a single wavelength one cannot use a simple fluid dynamic model to predict complex room response issues.

Yes they can.

When one learns how to think three dimensionally or spatially, they can see what's going on in a room as plain as one's hand in front of their face. Example, as long as one knows the rules and what the variables are, complex math equations are easy. That sort of thing.

The first trick is to know it can be done. Until then it seems impossible.

I have few talents but one of my talents is the ability to see and think three dimensionally and it gets old people telling me I can't do what I can do, all day long.

Open a wall up and the standing waves are immediately redirected. It's an option that most don't think of.

We can spend many thousands on extra subwoofers, sound panels and EQ solutions when for a few hundred dollars in materials, a wall (even if load bearing), if aesthetically possible, can simply be opened up. One should never discount the possibilities nor should those who think differently be discouraged with ridicule due to another's inability to understand.

Before knocking what I have to post, how about exploring the possibilities?

-
Edited by BeeMan458 - 12/18/12 at 6:33am
post #7622 of 9372
Quote:
Originally Posted by BeeMan458 View Post

It's well known the principals of fluid dynamics apply directly to room acoustics.
Opening up a room's reflective surfaces will correct for standing waves. Not a laughable reality.
Using the next room over as a sonic baffle or "bass trap" is a reality.
Changing the angle of a room's reflective surfaces will reduce standing waves.
Despite your disagreement or lack of understanding with what I have to post, personal attacks or holding a forum member out for derision is not allowed. Kindly stop attacking me.
-

Please post the fluid dynamics equations which one would use to calculate the effectiveness of your proposed solutions for a given room.
post #7623 of 9372
Quote:
Originally Posted by BeeMan458 View Post

Yes they can.
When one learns how to think three dimensionally or spatially, they can see what's going on in a room as plain as one's hand in front of their face.
The first trick is to know it can be done.
I have few talents but one of my talents is the ability to see and think three dimensionally and it gets old people telling me I can't do what I can do all day long.
Open a wall up and you redirect the standing wave.
Is that one of those cartoons you have running through your head?

Hey, you said it, I didn't.

Craig
post #7624 of 9372
Quote:
Originally Posted by BeeMan458 View Post

Yes they can.
When one learns how to think three dimensionally or spatially, they can see what's going on in a room as plain as one's hand in front of their face.

The issue isn't thinking in three dimensions, it's doing so at 15,000 odd wavelengths simultaneously.
post #7625 of 9372
posts deleted: move on please
post #7626 of 9372
I have no idea what was deleted but just wanted to say this.
Quote:
Originally Posted by BeeMan458 View Post

Yes they can.
When one learns how to think three dimensionally or spatially, they can see what's going on in a room as plain as one's hand in front of their face. Example, as long as one knows the rules and what the variables are, complex math equations are easy. That sort of thing.
The first trick is to know it can be done. Until then it seems impossible.
I have few talents but one of my talents is the ability to see and think three dimensionally and it gets old people telling me I can't do what I can do, all day long.
Open a wall up and the standing waves are immediately redirected. It's an option that most don't think of.
We can spend many thousands on extra subwoofers, sound panels and EQ solutions when for a few hundred dollars in materials, a wall (even if load bearing), if aesthetically possible, can simply be opened up. One should never discount the possibilities nor should those who think differently be discouraged with ridicule due to another's inability to understand.
Before knocking what I have to post, how about exploring the possibilities?
-
Quote:
Originally Posted by bfreedma View Post

Please post the fluid dynamics equations which one would use to calculate the effectiveness of your proposed solutions for a given room.

I don't think BeeMan is wrong here but I will say that properly opening up a wall is likely going to cost. There seems to be an adequate amount of literature supporting things like fluid dynamics not to mention finite element analysis when dealing with standing waves and the like. It seems to be a rather complex issue perhaps better left to comprehensive software packages designed to address these issues. And while it may seem flippant on BeeMan's part, I don't find it especially hard to believe that he can spatially visualize such concepts no more than I can find it hard to believe that there are some physicists who have visual concepts or multidimensional space, Rajon Rondo knowing just how and where to pass the ball, a mechanic porting and polishing things to improve fuel/air flow (same thing applies to rounding over the inside of the cabinet) or Gary Kasparov being able to assess a chess position 10 moves into the future.

I certainly don't have such an ability and would be rather loathe to start tearing down walls to address such problems but then my listening spaces tend to be open.
post #7627 of 9372
Quote:
Originally Posted by Chu Gai View Post

I have no idea what was deleted but just wanted to say this.
I don't think BeeMan is wrong here but I will say that properly opening up a wall is likely going to cost. There seems to be an adequate amount of literature supporting things like fluid dynamics not to mention finite element analysis when dealing with standing waves and the like. It seems to be a rather complex issue perhaps better left to comprehensive software packages designed to address these issues. And while it may seem flippant on BeeMan's part, I don't find it especially hard to believe that he can spatially visualize such concepts no more than I can find it hard to believe that there are some physicists who have visual concepts or multidimensional space, Rajon Rondo knowing just how and where to pass the ball, a mechanic porting and polishing things to improve fuel/air flow (same thing applies to rounding over the inside of the cabinet) or Gary Kasparov being able to assess a chess position 10 moves into the future.
I certainly don't have such an ability and would be rather loathe to start tearing down walls to address such problems but then my listening spaces tend to be open.
Hi Chu,

Obviously, if you change the reflecting surfaces, you change the acoustics of the room. Cutting a hole in the wall will "change" the acoustics. However, what we don't know is whether it will improve or degrade the acoustics. BeeMan didn't provide us with any of the higher level math or the computational flow dynamics to prove that opening a hole in the wall will actually result in an improvement. Therefore, it's a rather huge leap to suggest that Ashi go ask his Dad if he can cut a hole in the wall on the off-chance that it might make his subwoofer sound better.
Quote:
Originally Posted by Ashi777 View Post

Hey guys,
Me and my dad are worried about the structure inside of the walls coming loose, getting cracks and all. The house is brand new, it was just built last year. Half of the room is windows. (Obviously we didn't plan to keep a monster in there wink.gif ) But I dont hear them rattling, mainly the walls on the other side.
So my question is should I be worried?
Could I get a bit of detail on the answers please.
Cheers guys!
post #7628 of 9372
You're 100% right that we don't know what the change would be. One could, if they were so inclined and happened to have a relatively sealed room with doors and windows that opened to conduct their own measurements under different scenarios. 'Course you just might muck up the speaker's responses too.
post #7629 of 9372
Hi guys,

Please cool off the attacks, and thanks markrubin for cleaning things up.

BeeMan458, the seeming attacks you are getting are not directly related to the ideas posed but rather how they are stated and delivered without the possibility of fault. I'm not saying this is what you are intending, especially having spoken, but this is what others are perceiving and inferring.

I have friends working on some of the most advanced CFD modeling of low frequency room behavior being done with multiple subwoofers solutions, and it's anything but intuitive at first glance.

Once you have real measurements from a few locations confirming what is happening in a room it is very possible to have some confidence in what changing a wall or surface will do to a specific problem, but it is very hard to know that other collateral effects will not come with it.

I've posted here and elsewhere that with a single subwoofer in a room, I first look to see what is the most structurally solid corner or wall. Windows and openings to other spaces are less confining than an exterior wall on a main floor, and in basements we often see what looks like a symmetrical room to only then find that some walls are backed by the foundation, while others are just 1-2 layers of drywall which pass low frequencies much more readily. In such cases you will see the observed response to the listening position change while moving closer to or away from the solid wall or corner. Most often we see a moving dip/peak which correlates well to the dimensions involved. For those rooms with left-right construction symmetry and subs on a front wall, this plays a big part in why 2 subwoofers at the front wall of the room tend to have minimal benefit over a single subwoofer in the corner or center of the front wall.

Once again, measurement is key if you want to get deeper into this level of system optimization. Without measurements of the real room, you're guessing.
post #7630 of 9372
Quote:
Originally Posted by Mark Seaton View Post

BeeMan458, the seeming attacks you are getting are not directly related to the ideas posed but rather how they are stated and delivered without the possibility of fault. I'm not saying this is what you are intending, especially having spoken, but this is what others are perceiving and inferring.

Thank-you to you and thank-you Chu Gai for the thoughtfulness and understanding in both of your replies.
post #7631 of 9372
Quote:
Originally Posted by BeeMan458 View Post

When one learns how to think three dimensionally or spatially, they can see what's going on in a room as plain as one's hand in front of their face. Example, as long as one knows the rules and what the variables are, complex math equations are easy. That sort of thing.
The first trick is to know it can be done. Until then it seems impossible.
I have few talents but one of my talents is the ability to see and think three dimensionally and it gets old people telling me I can't do what I can do, all day long.
Open a wall up and the standing waves are immediately redirected. It's an option that most don't think of.
We can spend many thousands on extra subwoofers, sound panels and EQ solutions when for a few hundred dollars in materials, a wall (even if load bearing), if aesthetically possible, can simply be opened up. One should never discount the possibilities nor should those who think differently be discouraged with ridicule due to another's inability to understand.
Before knocking what I have to post, how about exploring the possibilities?
-
Quote:
Originally Posted by BeeMan458 View Post

Thank-you to you and thank-you Chu Gai for the thoughtfulness and understanding in both of your replies.
OK, sure.. some sweet strokes from Mark and Chu... that's all nice... but you have still not unequivocally proven that cutting a hole in the wall will *improve* the acoustics in Ashi's dad's room. Mark's response demonstrates the absolutely unpredictable nature of this whole undertaking, and the unquestionable need for in-room measurements.

Please provide the higher level math, or the computational flow dynamics, or at least the 3-dimensional modeling, (which you proclaim to have the ability to visualize in your head, but not to communicate on the internet), that would prove there would be an improvement by cutting a hole in the wall. Does the complete wall of glass on the right side of the room have any impact on your recommendation? Where do you suggest he cut the hole in the wall? Also provide the optimal dimensions of that hole. Short of that, at least show that there is a better than 50/50 chance that there would be an improvement by cutting *any* hole in the wall.. Otherwise, it's all in your head, and it's probably one of those cartoons you visualize. rolleyes.gif

Craig
post #7632 of 9372
Quote:
Originally Posted by craig john View Post

Please provide the higher level math, or the computational flow dynamics, or at least the 3-dimensional modeling, (which you proclaim to have the ability to visualize in your head, but not to communicate on the internet), that would prove there would be an improvement by cutting a hole in the wall.

Since I don't have the math, the math won't be forth coming. No, there's no three dimensional modeling to share as other than being able to see something in the mind, doesn't mean there's a boatload of modeling to share or I'm in error. Remove a reflective wall and you remove the standing wave the reflective wall causes. But since you can't see or understand, in your way of thinking, it doesn't exist. All you're doing is intentionally stirring the pot. The Mod said move along and that's what I'm doing.

-
Edited by BeeMan458 - 12/18/12 at 7:49pm
post #7633 of 9372
Quote:
Originally Posted by BeeMan458 View Post

Remove a reflective wall and you remove the standing wave the reflective wall causes.
You also remove the cabin gain that the reflective wall causes. Few rooms will find that a positive change.
Quote:
Mark's response demonstrates the absolutely unpredictable nature of this whole undertaking.
It's a lot more predictable than one might think, but as there are so many calculations involved it's far from easy. But 20 years ago it took ten pages of calculations and a week's work to design speakers with T/S specs, and now software does it in a few minutes. That same ability is coming closer every day where room response is concerned.
Edited by Bill Fitzmaurice - 12/18/12 at 8:03pm
post #7634 of 9372
Hey guys,

Thank you for all the input on this complex matter everyone.

I am absolutely sure that Beeman wasn't trying to mislead anyone with his suggestion. He was just putting an idea out there. I never knew that opening up gaps in a room could solve these modal issues. But now I do!

Unfortunately I haven't been able to move the sub. Had some work to attend to. It shall happen tomorrow.

Sorry for the hold up. Not getting much further with the issue since I haven't changed the position. Bear with me a little longer please! smile.gif Ill keep you updated.

Cheers guys
Ash
post #7635 of 9372
Quote:
Originally Posted by Bill Fitzmaurice View Post

You also remove the cabin gain that the reflective wall causes. Few rooms will find that a positive change.

Gain or smooth response, that is the question. It's all about perspective, correcting for nulls or giving up some gain that can easily be compensated for with a bigger boat; larger amplifiers and drivers. Rooms don't think nor do they have feelings. Rooms are inert. By removing standing waves, I find smoothing out a room's response to be a positive change. Any loss of gain is easily compensated for by adding more subwoofer. That's the benefit of buying a pair of SubMersive HP's, more subwoofer.

-
post #7636 of 9372
Quote:
Originally Posted by Ashi777 View Post

I am absolutely sure that Beeman wasn't trying to mislead anyone with his suggestion. He was just putting an idea out there. I never knew that opening up gaps in a room could solve these modal issues. But now I do!

Thanks Ashi, that's all it was, conversation. Two guys talking, sharing ideas so as to help each other better understand the forces of the Universe.

Folks think nothing about re-pitching a roof, landscaping a yard with tennis court, swimming pool and BBQ bar or creating a dedicated Home Theater room in their unfinished basement. In the same vein, the idea of opening a room up to help deal with standing wave issues should be discussed in the same light as one who wants to remodel a kitchen by opening up walls or putting a second story on their one story structure. It's going take time, money and planning but in the end, when finished, it's no big deal and nobody should be calling anybody crazy for doing so.

Any loss of room gain by opening a room up, can easily be corrected for by adding an additional SubMersive HP. It's win, win; Mark sells another sub and someone loses their standing wave issues.

Thanks again for the positive thought.

-
Edited by BeeMan458 - 12/19/12 at 3:43am
post #7637 of 9372
Quote:
Originally Posted by BeeMan458 View Post

Quote:
Originally Posted by Bill Fitzmaurice View Post

You also remove the cabin gain that the reflective wall causes. Few rooms will find that a positive change.

Gain or smooth response, that is the question. It's all about perspective, correcting for nulls or giving up some gain that can easily be compensated for with a bigger boat; larger amplifiers and drivers. Rooms don't think nor do they have feelings. Rooms are inert. By removing standing waves, I find smoothing out a room's response to be a positive change. Any loss of gain is easily compensated for by adding more subwoofer. That's the benefit of buying a pair of SubMersive HP's, more subwoofer.

-

To be blunt, you've recently learned some new words but have no idea what they actually mean or how to apply the concepts behind them.

Bill, Craig, and others could help with that if you would slow down and think about their posts instead of being so utterly convinced you have a new and simple solution to a well known acoustical challenge.
post #7638 of 9372
Quote:
Originally Posted by bfreedma View Post

To be blunt, you've recently learned some new words but have no idea what they actually mean or how to apply the concepts behind them.
Bill, Craig, and others could help with that if you would slow down and think about their posts instead of being so utterly convinced you have a new and simple solution to a well known acoustical challenge.

If you want to continue, please take it to PM

Thanks.

-
Edited by BeeMan458 - 12/19/12 at 3:20am
post #7639 of 9372
Quote:
Originally Posted by BeeMan458 View Post

If you want to continue, please take it to PM
Thanks.
-

This is a public forum - if you want to propose new "theories", they will get challenged.

Here's a way to solve the problem - validate your claims. Have an acoustical engineer model 10 rooms with diverse shapes and construction materials. You visualize the solution for where to best place a new opening to improve in room bass response across the common criteria. The acoustical engineer can run the computational flow dynamics and 3 dimensional modeling and come up with an answer using accepted science. If you consistently align with the math within a few inches in each dimension, then you can feel free to gloat all you like.
post #7640 of 9372
Quote:
Originally Posted by Ashi777 View Post


I am absolutely sure that Beeman wasn't trying to mislead anyone with his suggestion. He was just putting an idea out there. I never knew that opening up gaps in a room could solve these modal issues. But now I do!

 

 

The main thing, Ash, is that it is easy for you to try. You have a pair of big doors in back of your room. Open them and see if it makes a difference. You don't need to knock walls down - just open the doors! Not very scientific, but it will take you 10 seconds and it's free.  Of course, the doors might be in the 'wrong place' but it's such a simple experiment that you could try.  Personally, I think you can probably get what you are looking for by repositioning the sub and/or MLP and applying some form of EQ to the bottom end - AntiMode, XT32 etc. I think it is significant that Mark has 'tuned' many rooms for his SubMs and, AFAIK, he hasn't yet knocked holes in anyone's house ;)


Edited by kbarnes701 - 12/19/12 at 4:01am
post #7641 of 9372
I am in my second home theater. The previous one had double doors in the back of the room. Opening either or both of the made a change. Just not a positive one. In my current theater, the door is on the rear left wall and opening it also makes a negative (but more subtle) change.

Arbitrarily opening up a wall in a room without knowing EXACTLY where, how large and what results moght be seen is not science. And that 's true even if you can visualize in 8 dimensions!

As Craig has asked multiple times, show us the math.
post #7642 of 9372
Quote:
Originally Posted by audioguy View Post

Quote:
Originally Posted by djbluemax1 View Post

The ONLY way to stop that from happening is:
a) reduce or eliminate the reflection, thereby reducing or eliminating the cancellation the reflected wave was producing (i.e. bass traps)
b) move the source (subwoofer) and/or the listening position, effectively altering the timing of the waves so the cancellation happens in a location you aren't in and don't care about.
Max

If (a) or (b) does not completely solve the problem (it did not in my room), I would add (c) add an additional sub(s).
Absolutely. If adding subs is a viable option, it's usually quite an effective one. The main reason many (most?) of us go with multiples is for the benefit in smoothing out the frequency response, as opposed to compensating for lost cabin gain after knocking holes in the walls.

I think most folks considering multiple subs are more likely to sample how adding multiples in different positions in the room affect/even out the bass BEFORE making holes in the walls rather than simply trying to use multiples to compensate for a reduction in cabin gain after knocking holes in the walls.

Seems odd for someone to suggest doing it the other way round.


Max
post #7643 of 9372
Quote:
Originally Posted by audioguy View Post

Arbitrarily opening up a wall in a room without knowing EXACTLY where, how large and what results moght be seen is not science. And that 's true even if you can visualize in 8 dimensions!

Nowhere in my comments did I suggest arbitrarily opening up walls. There are only three dimensions and the continuum. And nowhere in my comments am I denying the existence of anything connected with science. The human mind can do much more then you're willing to give it credit for. I'm quite sure, if given the chance, everybody here can do what I suggest.

Quote:
As Craig has asked multiple times, show us the math.

Instead of arguing, try understanding something that doesn't meet with your bias'. I've already stated, there will be no math forthcoming as this isn't a math problem. This is a visualization problem. I responded to Ashi777, it's a basic concept and he got it. If you want to continue, please go to PM.

-
Edited by BeeMan458 - 12/19/12 at 6:16am
post #7644 of 9372
Quote:
Originally Posted by BeeMan458 View Post

Nowhere in my comments did I suggest arbitrarily opening up walls. There are only three dimensions and the continuum. And nowhere in my comments am I denying the existence of science.
I've already stated, there will be no math forthcoming as this isn't a math problem. This is a visualization problem. I responded to Ashi777, it's a basic concept and he got it.
If you want to continue, please PM me.
-

Yes most of us got that when you explained setting your sound system at certain angles to walls and openings.
post #7645 of 9372
Quote:
Originally Posted by Gary J View Post

Yes most of us got that when you explained setting your sound system at certain angles to walls and openings.

Then that settles it. Now, how about those Seaton Subs of yours? Is one better served by a pair of 18" subs, one driver in each sub or a pair of 15" subs, two drivers that are opposite each other; four drivers total?

-
Edited by BeeMan458 - 12/19/12 at 6:49am
post #7646 of 9372
Question about cancellation. If I added a 3rd SubM F2 toward the rear of my room (nearly 11ft across from the front left SubM with a slight offset), would I experience cancellation between the front left and rear left subs? I would normally think yes, but looking at Art Sonneborn's room, the 4 Submersives are right next to each other with no (assumed) cancellation...
post #7647 of 9372
Quote:
Originally Posted by BeeMan458 View Post

Nowhere in my comments did I suggest arbitrarily opening up walls -

Then tell him/us where you would like him to open the wall, the size of the opening the results he can expect and the rational for your recommendations.

I already said opening walls can make a difference . (In my case, they were negative differences).

And why would I want these questions on a PM? I'm sure there are many interested in what your specific recommendations are and why.
post #7648 of 9372
Quote:
Originally Posted by BeeMan458 View Post

Then that settles it. Now, how about those Seaton Subs of yours? Is one better served by a pair of 18" subs, one driver in each sub or a pair of 15" subs, two drivers that are opposite each other; four drivers total?
-

You know I keep meaning to ask Mark if the two drivers in a Sub M is closer in effect to having two separate subs or just one big one. What are the benefits of two drivers beyond the obvious?
post #7649 of 9372
Quote:
Originally Posted by audioguy View Post

Then tell him/us where you would like him to open the wall, the size of the opening the results he can expect and the rational for your recommendations.
I already said opening walls can make a difference . (In my case, they were negative differences).
And why would I want these questions on a PM? I'm sure there are many interested in what your specific recommendations are and why.

rolleyes.gif
post #7650 of 9372
Quote:
Originally Posted by BrolicBeast View Post

If I added a 3rd SubM F2 toward the rear of my room (nearly 11ft across from the front left SubM with a slight offset), would I experience cancellation between the front left and rear left subs?
Yes, and no. You'll get cancellations at some frequencies, increases at some frequencies. If this was outdoors it would be a simple matter to calculate. Indoors not so much, because not only are the direct waves from all the subs part of the equation, so are all the reflections of all those waves off every boundary in the room. But chances are matters will be improved. What you're mainly dealing with is the boundary reflection nulls and peaks from the existing subs. As the boundary reflection nulls and peaks with the third sub will occur at different frequencies than the other two, because it's in a different spot, the overall result will probably be smoother. Before I invested in a third sub, though, I'd move one of them from the front to the side or rear. Having both in front means that some modes will be the same, or very close to the same, for both in some sections of the room.
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