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Discussion Starter · #1 ·
would there be any benefit to making the inside of a speaker box similat to an anachoic(sp?) chamber? It would eliminate any standing waves and pretty much sound proof a box to my knowledge so i thought it would have some very beneficial properties toward sound quality.
 

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Originally Posted by Kimeran /forum/post/19569828


would there be any benefit to making the inside of a speaker box similat to an anachoic(sp?) chamber? It would eliminate any standing waves and pretty much sound proof a box to my knowledge so i thought it would have some very beneficial properties toward sound quality.

That's called damping, and it's SOP.
 

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Discussion Starter · #3 ·
would you mind expanding on that a bit for me please?


I do not know what SOP means.


The reason I ask this too is because i didnt know if it had a different effect from just putting foam on the inside and such.
 

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Quote:
Originally Posted by Kimeran /forum/post/19572943


would you mind expanding on that a bit for me please?


I do not know what SOP means.


The reason I ask this too is because i didnt know if it had a different effect from just putting foam on the inside and such.

Standard Operating Procedure. Foam and such are what's used to make anechoic chambers anechoic.
 

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Quote:
Originally Posted by Kimeran /forum/post/19569828


pretty much sound proof a box to my knowledge

Not a correct assumption, I doubt you could put enough sound absorbing materials inside a speaker box to "soundproof" it. This is similar to the notion of adding fiberglass insulation to the walls for soundproofing a theater room. It is going to help a little bit at the higher frequencies but lower frequencies will pass right through.


There is an excellent library of articles on the subject at soundproofingcompany.com
 

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Quote:
Originally Posted by Kimeran /forum/post/19569828


would there be any benefit to making the inside of a speaker box similat to an anachoic(sp?) chamber? It would eliminate any standing waves and pretty much sound proof a box to my knowledge so i thought it would have some very beneficial properties toward sound quality.

Standing waves are a function of the wavelength of the wave, the boundary conditions, and the density of the medium.
 

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Discussion Starter · #7 ·
hmm, ok, i find all of this to be very interesting obviously but i obviously havent even touched the tip.


I was thinking that if you made a box that has tons of trigular shapes, like the anachoic chambers that speakers are tested in...that you could have a port that would not add any coloration to the speakers.


but this is from an uneducated perspective on the matter.
 

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Quote:
Originally Posted by Kimeran /forum/post/19574689


hmm, ok, i find all of this to be very interesting obviously but i obviously havent even touched the tip.


I was thinking that if you made a box that has tons of trigular shapes, like the anachoic chambers that speakers are tested in...that you could have a port that would not add any coloration to the speakers.


but this is from an uneducated perspective on the matter.

You can't make them long enough to get the required LF response inside an enclosure. The length of the wedges inside an anechoic chamber determines LF response; a wavelength at 20Hz is >7m, substantially larger than the average speaker enclosure.
 

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substantially larger than the average speaker enclosure

Everything is relative with Kryptonitewhite in the house!
 

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Quote:
Originally Posted by Kimeran /forum/post/19574689



I was thinking that if you made a box that has tons of trigular shapes, like the anachoic chambers that speakers are tested in.

The acoustical foam used in many cabs does just that, but the shape only affects shorter wavelengths. In most cases the foam shape alone doesn't accomplish anything, especially where woofers are concerned, where the total volume of the damping is what counts. It looks pretty, though.
 

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Discussion Starter · #11 ·
i see.

So basically doing this sort of treatment will only contain the wavelengths from the tweeters and maybe most of the mids. I am assuming alot of this has to do with the size of the driver.


So is there any benefit to having an enclusure that has no parallel sides then? wether it is triangular or a circular enclosure that has the foam treatment?
 

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Quote:
Originally Posted by Bill Fitzmaurice /forum/post/19575313


The acoustical foam used in many cabs does just that, but the shape only affects shorter wavelengths. In most cases the foam shape alone doesn't accomplish anything, especially where woofers are concerned, where the total volume of the damping is what counts. It looks pretty, though.

I am building 4 sealed subs. Should I dampen the boxes and what kind of dampening material should I use? Link?
 

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Quote:
Originally Posted by UNICRON-WMD /forum/post/19578491


I am building 4 sealed subs. Should I dampen the boxes and what kind of dampening material should I use? Link?

What do the plans say? It should be specified.

Quote:
So is there any benefit to having an enclusure that has no parallel sides then? wether it is triangular or a circular enclosure that has the foam treatment?

Here also it's a matter of the wavelengths of the speaker pass band relative to the internal dimensions of the cab. It can be very significant or not matter at all/
 

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Discussion Starter · #14 ·
its obvious that it would be strongly beneficial to pick up a book on this matter to get a strong, firm grasp on this matter.


However, before I do I have a few more questions.


When you have a speaker such as the "blade" by KEF where the woofers cancel out the waves inside the box does that always work or are there times where this also does not have any benefit?


Second: what frequencey does it become pointless to add any extra damping to a box? I suspect this is around 60hz.


I know this relies largely on the size of the box but I am looking for an average number.
 

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Quote:
Originally Posted by Kimeran /forum/post/19583229


When you have a speaker such as the "blade" by KEF where the woofers cancel out the waves inside the box does that always work or are there times where this also does not have any benefit?

That's not why they're used like that. Opposing LF drivers will create nearly (no two drivers are ever identical) equal and opposite forces from the movement of the cones. By coupling them tightly mechanically the net result should theoretically be zero vibrational input from the driver frames into the cabinet.


None of this is new for KEF; my 20yo 104/2 used a steel rod between the LF drivers for exactly this reason.

"Force Cancelling


With four new 10in. (250mm) low frequency drivers, bass extension is phenomenal - and notably undistorted, even when played loud. This is because KEF's ingenious Force Cancelling technology prevents the considerable excursion of such large cones from exciting the cabinet walls and causing secondary radiation that might otherwise muddy the sound. The force produced by the drivers is so strong that the rear magnet assemblies have to be glued directly to each other in order to obtain the full benefit of this technology."

 
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