Stupid Question

[Sencheezy 689]

I've always just wonderd this, what would happen, or what effect would it have to put sound deadening or Mass Loaded Vinyl inside of your box? I know it sounds stupid, but just curious I guess lol

[altoncustomtech 773]

Um, you'd waste money?

All I've ever heard about doing it is that it would do no good what so ever. However, I used to know some old school enthusiasts who would line a few walls in a ported enclosure with quilt batting claiming it helped in some way. Never did a before and after comparison to see if there really was any difference though. It would probably be tough to keep something like that in the enclosure too with the large ports, high power, and sheer volume of air most of us are moving with our subs and enclosures. Most of these guys were building simpler, smaller, and lower power home speakers.

Not a dumb question though.

[///M5 2,833]

MLV stops the transmission of sound. In the case of the box that is of dubious benefit. Obviously if you have a very poorly built enclosure some treatments could be a positive but that isn't the right way to fix the problem.

However, I used to know some old school enthusiasts who would line a few walls in a ported enclosure with quilt batting claiming it helped in some way.

For high frequencies it does, just not for sub frequencies.

[Sencheezy 689]

Hmmmm, interesting. See, the way I was looking at it is. If you have a material that bounces sound waves back in, then if you were to put that in a box, then maybe it would push the sound waves out the ported box even faster and produce more sound:ughdunno: lol thats why I said it was a stupid question, cuz if that was the case then everybody would be doing it lol. Thanx for the input tho, I was just always wonderd about what if lol.

[altoncustomtech 773]

Hmmmm, interesting. See, the way I was looking at it is. If you have a material that bounces sound waves back in, then if you were to put that in a box, then maybe it would push the sound waves out the ported box even faster and produce more sound:ughdunno: lol thats why I said it was a stupid question, cuz if that was the case then everybody would be doing it lol. Thanx for the input tho, I was just always wonderd about what if lol.

First of all, neither MLV or deadener bounce any waves by design, the MLV will absorb them though. Second, IF the waves were some how sped up it would cause the frequency to rise which would be VERY bad in any situation and screw everything up in the response.

It's still not a stupid question, or theory. Nothing wrong with trying to think outside the box, and if you don't ask you'll never learn anything.

[Sencheezy 689]

Hmmmm, interesting. See, the way I was looking at it is. If you have a material that bounces sound waves back in, then if you were to put that in a box, then maybe it would push the sound waves out the ported box even faster and produce more sound:ughdunno: lol thats why I said it was a stupid question, cuz if that was the case then everybody would be doing it lol. Thanx for the input tho, I was just always wonderd about what if lol.

First of all, neither MLV or deadener bounce any waves by design, the MLV will absorb them though. Second, IF the waves were some how sped up it would cause the frequency to rise which would be VERY bad in any situation and screw everything up in the response.

It's still not a stupid question, or theory. Nothing wrong with trying to think outside the box, and if you don't ask you'll never learn anything.

Thanks for the response Alton, I appreciate it. And I do see your point. Your a good man

[REVpuggie 23]

wanted to quote mr. Garrison from South Park ... but I shouldnt

nothing to add besides that , you got the answers you were looking for .

[///M5 2,833]

The speed of sound is a constant in your environment. You cannot speed up or slow down waves. You can shift their frequency though which is always bad. This is mostly realized when you have a speaker play a very large range of frequencies with high dynamics. In that case you can have what is called Doppler distortion which is caused by the cone moving heavily at a frequency and trying to play another at the same time. It gives you some frequency smearing and is part of the reason that audiophiles regularly prefer low xmax drivers.

[edouble101 314]

If it is that big of a concern you should design an enclosure without any parallel walls and internally made of constrained layer materials (dampening sort of). This will greatly improve sound (not output!) over a standard 6 wall rectangular/square enclosure made of MDF.

[Impious 1,476]

If it is that big of a concern you should design an enclosure without any parallel walls and internally made of constrained layer materials (dampening sort of). This will greatly improve sound (not output!) over a standard 6 wall rectangular/square enclosure made of MDF.

A lack of parallel walls will have zero affect in the subbass. The purpose of non-parallel enclosure walls is to reduce standing waves within the enclosure. For subbass, this isn't going to be an issue to begin with as the dimensions of the enclosure are much shorter than the wavelengths of the sound waves, so standing waves are not going to develop.

For subbass, I doubt there would be an audible difference between a well designed and braced MDF enclosure and some other exotic enclosure material. The resonant frequency of the panels is gong to be too high, and any losses from panel resonance/flexing is going to be too small compared to the driver output to audibly affect the sound. On a meter, I doubt you would see much of a difference either as long as the MDF enclosure was properly braced to begin with.

Notice I explicitly stated I discussing affects in the subbass frequency range here. As we move up the frequency spectrum where the wavelengths are shorter and you are closer to the Fs of the enclosure panels, those issues can start to become problems (although there are far less exotic means of dealing with them). External panel shape can also affect frequency response in other ways in the higher frequency region....but that's neither here nor there.

[edouble101 314]

If it is that big of a concern you should design an enclosure without any parallel walls and internally made of constrained layer materials (dampening sort of). This will greatly improve sound (not output!) over a standard 6 wall rectangular/square enclosure made of MDF.

A lack of parallel walls will have zero affect in the subbass. The purpose of non-parallel enclosure walls is to reduce standing waves within the enclosure. For subbass, this isn't going to be an issue to begin with as the dimensions of the enclosure are much shorter than the wavelengths of the sound waves, so standing waves are not going to develop.

For subbass, I doubt there would be an audible difference between a well designed and braced MDF enclosure and some other exotic enclosure material. The resonant frequency of the panels is gong to be too high, and any losses from panel resonance/flexing is going to be too small compared to the driver output to audibly affect the sound. On a meter, I doubt you would see much of a difference either as long as the MDF enclosure was properly braced to begin with.

Notice I explicitly stated I discussing affects in the subbass frequency range here. As we move up the frequency spectrum where the wavelengths are shorter and you are closer to the Fs of the enclosure panels, those issues can start to become problems (although there are far less exotic means of dealing with them). External panel shape can also affect frequency response in other ways in the higher frequency region....but that's neither here nor there.

Like I said if it is that big of a concern. I gave two common methods for enclosure design that could be adopted for subwoofer enclosures if the builder feels enthusiastic.

[///M5 2,833]

If it is that big of a concern you should design an enclosure without any parallel walls and internally made of constrained layer materials (dampening sort of). This will greatly improve sound (not output!) over a standard 6 wall rectangular/square enclosure made of MDF.

A lack of parallel walls will have zero affect in the subbass. The purpose of non-parallel enclosure walls is to reduce standing waves within the enclosure. For subbass, this isn't going to be an issue to begin with as the dimensions of the enclosure are much shorter than the wavelengths of the sound waves, so standing waves are not going to develop.

For subbass, I doubt there would be an audible difference between a well designed and braced MDF enclosure and some other exotic enclosure material. The resonant frequency of the panels is gong to be too high, and any losses from panel resonance/flexing is going to be too small compared to the driver output to audibly affect the sound. On a meter, I doubt you would see much of a difference either as long as the MDF enclosure was properly braced to begin with.

Notice I explicitly stated I discussing affects in the subbass frequency range here. As we move up the frequency spectrum where the wavelengths are shorter and you are closer to the Fs of the enclosure panels, those issues can start to become problems (although there are far less exotic means of dealing with them). External panel shape can also affect frequency response in other ways in the higher frequency region....but that's neither here nor there.

Like I said if it is that big of a concern. I gave two common methods for enclosure design that could be adopted for subwoofer enclosures if the builder feels enthusiastic.

Replace the italics with "wasting time" and you are spot on. 2 main reasons. This is a sub and this is a car.

[Sencheezy 689]

Thanks for all the responses, yeah, after getting all the information from you guys, I feel pretty dum, but educated at the same time lol. Now I don't even know why I thought that in the first place, I guess I was just thinking you could some how "push" the soundwaves to make a louder output which I now know is completely wrong. Which is why I started the whole question hypothetically. Again, thanx for the input, I gr8ly appreciate it.

[altoncustomtech 773]

You can't push the sound waves, but you can "concentrate" (for lack of a better word at the moment, M5 I know you have a better term for it) them. Think of yelling through a traffic cone for example, there are horn loaded enclosures than can do the kind of thing your idea was moving toward. However, if you remember Impious's post on the length of the waves, it takes a VERY large and long horn to effect the sound waves in that manner and are not really ideal for car audio use due to the size. People have done them, don't get me wrong. I just have never seen one in person to give you any idea of how it worked out. I would still stick with the idea that a properly built, braced and tuned ported enclosure will out perform any other wild idea, like a transmission line or horn, that was done wrong just to fit in the car. Just my .02

[Sencheezy 689]

You can't push the sound waves, but you can "concentrate" (for lack of a better word at the moment, M5 I know you have a better term for it) them. Think of yelling through a traffic cone for example, there are horn loaded enclosures than can do the kind of thing your idea was moving toward. However, if you remember Impious's post on the length of the waves, it takes a VERY large and long horn to effect the sound waves in that manner and are not really ideal for car audio use due to the size. People have done them, don't get me wrong. I just have never seen one in person to give you any idea of how it worked out. I would still stick with the idea that a properly built, braced and tuned ported enclosure will out perform any other wild idea, like a transmission line or horn, that was done wrong just to fit in the car. Just my .02

Hmmmmmmmm, not to misinterpret what your saying. But with what your talking about, is this why I see some builds that put up very high numbers are useing thoz big long ass aeroports?? Is that the concept behind what your talking about? Or is that just a differnt ball park?

And thanks for your .02

[altoncustomtech 773]

Hmmmmmmmm, not to misinterpret what your saying. But with what your talking about, is this why I see some builds that put up very high numbers are useing thoz big long ass aeroports?? Is that the concept behind what your talking about? Or is that just a differnt ball park?

And thanks for your .02

Actually it is very different. When port area is increased (i.e. using a large port) the port length must increase as well. They're only doing what they have to in order to get the tuning they want with the port size they're using.

An actual horn loaded enclosure can vary in design greatly, but will at some point have some part of the enclosure passing through what looks like a small narrowing hallway in order to produce the horn loading effect. I'll see if I can find an example or two.

[altoncustomtech 773]

Here's a horn loaded enclosure.... notice how the port opening behind the sub is very small and as it travels around though the length it widens.... same idea as the traffic cone....

Folded horn enclosure

Another plan for one.... Autotuba

Here's a kinda horn.... Hybrid horn

[Sencheezy 689]

Here's a horn loaded enclosure.... notice how the port opening behind the sub is very small and as it travels around though the length it widens.... same idea as the traffic cone....

Folded horn enclosure

Another plan for one.... Autotuba

Alright, so your the man, thanx a lot bro. I understand better now, with the first link you showed, but the autoba lol, I don't think I would ever use, just don't understand it

But I have seen the folded horn before, and always wonderd about it. So, I'm getting the picture that every box has its own strength and weakness and are a base to base decision depending on the owner's prefrence and space availible. I'm not gonna sit here and ask you to list every box design and ask whats the benefit of each one kuz thaz dum and .

But in this case, relateing to my first question, would a Folded horn enclosure... how do I say this.... present a greater impact on the meter/owner then a normal L (Don't know the correct term)box if space permits?

[altoncustomtech 773]

Given the folded horn was properly tuned and built, yes, I would imagine it would be louder than an L configured slot ported enclosure. I've never had a chance to play with one, so I'm not sure exactly what the differences are, but from what I understand that is the preface and reasoning behind the horn loading design. Really need some input from some of the more seasoned members at this point.

[Sencheezy 689]

Given the folded horn was properly tuned and built, yes, I would imagine it would be louder than an L configured slot ported enclosure. I've never had a chance to play with one, so I'm not sure exactly what the differences are, but from what I understand that is the preface and reasoning behind the horn loading design. Really need some input from some of the more seasoned members at this point.

Thanks Alton

Can anybody else chime in on this one? M5/ Impious/Handcrafted Car audio, PTS, Fisher Customs/SSA

Edited January 11, 2011 by Sencheezy

[Duran 387]

http://www.audioxpress.com/magsdirx/ax/addenda/media/kolbrek2884.pdf

http://www.audioxpress.com/magsdirx/ax/addenda/media/kolbrek2885.pdf

Have fun

[Sencheezy 689]

http://www.audioxpre...kolbrek2884.pdf

http://www.audioxpre...kolbrek2885.pdf

Have fun

There will be no fun to be had reading!!! lmao

[Impious 1,476]

Just as an FYI, you aren't going to fit a horn that actually functions as a horn into the lower subbass region to fit into a car. Most of them won't fit reasonably into a house, unless the house is built around the horn.

Any "horn" that fits in a car, much less in a trunk, isn't functioning as an actual horn for very much of it's operating bandwidth.

[///M5 2,833]

And the same holds true for a Transmission Line. Consider you ask about impact on a meter you only have two choices. A simple ported or a 6th order bandpass -- they will be the alignments that yield the best results in the least amount of space (ie car). Considering your questions I would shy away from a 6th order as there are more variables that you should be playing with right now and it will limit its capability as a learning experience for you.

[Sencheezy 689]

And the same holds true for a Transmission Line. Consider you ask about impact on a meter you only have two choices. A simple ported or a 6th order bandpass -- they will be the alignments that yield the best results in the least amount of space (ie car). Considering your questions I would shy away from a 6th order as there are more variables that you should be playing with right now and it will limit its capability as a learning experience for you.

Yeah, I just :google:6th order bandpass, and I have seen those before, but from my understanding, they are very difficult to build and require persise measurement, so I don't ever see myself building one.... I understand what your saying about space as a limitation, but I have an explorer, never planning on doing a wall, but I do have 10-12 cu ft that i would be willing to sacrifice for a 18 or two like I had before. I like the design that Alton showed me @ http://forum.mwcaraudio.net/showthread.php?t=2662&highlight=horn

I didn't think that would take up that much space, of course unless this is not a true horn setup.