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smitske96 View Drop Down
Young Croc
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    Posted: 22 October 2021 at 2:29pm
Some time ago I was trying to find any info or papers about using boudaries to get extra gain from subwoofers. In this case I am not just talking about a wall or ceiling etc. But more like portable solutions, that are placed behind/besides the cabinets to profit from extra gain.
I can imagine some effects, but am more curious about some real data.

I am sure there is lots of info to find about the topic, but I think the language boundary prevents me from searching with the correct words.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote VECTORDJ Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2021 at 2:51pm
Older Altec designs used" Barn Doors" to increase low end output...In the "Klipsch Papers" Klipsch writes about  a "False Corner"....
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Conanski View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2021 at 3:13pm
A good link showing how boundaries affect loudspeaker response.. How Do Boundaries Affect Loudspeakers? (prosoundtraining.com)

The thing to remember is any structure that is large relative to the sound wavelengths in question becomes a boundary to those waves, so for example the speaker baffle itself is a boundary for high frequencies, and a big enough stack of subs will also act as a boundary to themselves starting at the highest frequencies of operation(shortest wavelengths) first and extending down as the stack grows in size. 

You may have seen the horn extensions used on some horn subs, there is a similar concept called barn doors that can be used with any style of speaker system that does somewhat act as a boundary, the extent to which it works very much depends on the size of that structure. 
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smitske96 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2021 at 3:34pm
@Conanski

I am aware of those papers/writeups but am more targeting to the boundary effect a fixed concrete stage can have where the subs are placed in a special cavity. 
In a local club they have a special brick housing around some MTL2's and am curious of there are any measurements about similar situations.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote toastyghost Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2021 at 4:01pm
Originally posted by smitske96 smitske96 wrote:

@Conanski

I am aware of those papers/writeups but am more targeting to the boundary effect a fixed concrete stage can have where the subs are placed in a special cavity. 
In a local club they have a special brick housing around some MTL2's and am curious of there are any measurements about similar situations.




https://www.prosoundweb.com/counterintuitive-cardioid-subwoofers-can-be-a-bit-claustrophobic/

Reference papers linked at the end.

https://www.aes.org/e-lib/browse.cfm?elib=20265
For horns, if you have access.

The effect is on the radiation impedance. You'll need to solve some double or quadruple integrals to look into it analytically for a given situation. Start with the Rayleigh integral and some acoustics textbooks - I recommend the ones by Frank Fahy to start.

Foundations of engineering acoustics https://g.co/kgs/ZtdwJi
Fundamentals of Sound and Vibration https://g.co/kgs/GTW87w

Edited by toastyghost - 22 October 2021 at 4:04pm
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