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Changing the Depth of DIY DBA
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Acoustics Pro
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September 24, 2021 - 12:34 pm
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Hello

I want to build and test the BDA from DIY plans but due to furniture occupying my room which is quite large but yet even if i move things to free up space, i can’t fit 16inch deep cabinets in spaces that would not sacrifice functionality and general aesthetics of the room even tho they look quite stunning.

So i have decided to go with modular design and i like the design that you have with those modules 24x24x12, but maybe i would go with 10. But as you know, that changes relationship of how 2 front walls would function.

I forgot the formula how deep the cabinet is in relation of frequency it “absorbs” i just remember it needs to be efficient for only quater wavelength.

My questions are :

1. If i change cabinet depths, how do i change 2 walls relation ( space between 2 walls that slow down the wave), i think they have to be in symbiosis with the wave it absorbs so they are frequency dependant . and also what is relation of air space (how much air fill i need) Foam thickness stays the same so i do not have yo worry about.

2. How much is bda effective with 10inch depth and 12 inch ?

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Chief Acoustics Engineer
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September 25, 2021 - 5:57 am
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The cabinet depth determines the resonant frequency of the unit or how low it will absorb energy at. A 10″ total depth would mean a resonant frequency of 50 Hz. You would not have any attenuation below that. If your room exhibits issues below that they will not be treated.

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October 9, 2021 - 11:27 am
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Dennis Foley said
The cabinet depth determines the resonant frequency of the unit or how low it will absorb energy at. A 10″ total depth would mean a resonant frequency of 50 Hz. You would not have any attenuation below that. If your room exhibits issues below that they will not be treated.  

I can live with 50 hertz. But do i need to change two front plates ? More specifically, the distance between them ?

Or because it is higher resonant frequency (50hz), the distance between them needs to change so they slow (phase canceling) or i can keep the distance between them just like blueprints ? Thanks

From my understanding, if you change depth, additional tuning of front plates is required to be fully effective but i am not expert. I just don’t want to build something that doesn’t work in full potential.

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October 9, 2021 - 3:54 pm
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It is 60 Hz. at that stated depth. The front walls remain the same.

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