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Old 28th November 2007, 12:07 PM   #1
cph2000 is offline cph2000  Denmark
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Default Bass in wall enclosure?

Hello,

Any idears on how to simulate the loading effects (i.e. freq. responce depending on driver and box size) of a shallow closed box hanging on a wall ?

I guess it would aproximate a closed box mounted in an infinite baffle ?

Help is much appreciated ..
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Old 28th November 2007, 02:03 PM   #2
MaVo is offline MaVo  Germany
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If the wavelength is big compared to the distance to the rear wall then there should be an addition with the sound that comes back from the wall, which should be a 3db boost if i am right. when the distance to the wall is 1/4 wavelength you get a cancelation notch because of the 180 degree phase shift. this notch will occur periodically at higher frequencies each time the reflected sound and the direct sound are of opposing phase (= comb filter). i dont know a program that takes everything into account. the directivity of the speaker should have a great influence on all this. perhaps you can make a simulation in akabak, but that will be a demanding adventure.

There will also be diffraction effects, which each box has to some degree. Additional to that, room modes and reflections will change the response.

this spreadsheet could be helpfull to see what the room does to the response:
http://www.pvconsultants.com/audio/reflection/rrc.htm

this one lets you simulate the diffraction:
http://www.tolvan.com/edge/
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Old 28th November 2007, 09:31 PM   #3
Svante is offline Svante  Sweden
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Default Re: Bass in wall enclosure?

Quote:
Originally posted by cph2000
Hello,

Any idears on how to simulate the loading effects (i.e. freq. responce depending on driver and box size) of a shallow closed box hanging on a wall ?

I guess it would aproximate a closed box mounted in an infinite baffle ?

Help is much appreciated ..
Just check the "Enable back wall" checkbox...

Click the image to open in full size.

The result is far from an infinite baffle in most cases.
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Old 28th November 2007, 09:49 PM   #4
cph2000 is offline cph2000  Denmark
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Default Re: Re: Bass in wall enclosure?

Quote:
Originally posted by Svante


Just check the "Enable back wall" checkbox...

Click the image to open in full size.

The result is far from an infinite baffle in most cases.

I just downloaded the demo version of basta, is the "enable back wall" feature disabled from this version (I only get the "Baffel step / edge diffraction" frame in the box tab) ?
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Old 29th November 2007, 11:50 PM   #5
Svante is offline Svante  Sweden
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Default Re: Re: Re: Bass in wall enclosure?

Quote:
Originally posted by cph2000



I just downloaded the demo version of basta, is the "enable back wall" feature disabled from this version (I only get the "Baffel step / edge diffraction" frame in the box tab) ?
Yes this feature is not free, but almost.
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