# IB Subwoofer Absorbtion



## Ayreonaut (Apr 26, 2006)

I have a few odd questions about IB sub interaction with rooms:

1. Does an IB sub do much in the way of bass absorbtion? (Could that be one of the reasons why people think that they sound so good?)

2. Would the absorbtion be different when the amp is on or off?

And finally a hair brained scheme:

3. If you installed two woofers IB style in opposite corners of a rectangular room, could you short circuit standing waves by wiring them together with no amp?


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## Darren (Apr 20, 2006)

1. I'm not sure what you mean by absorbtion...it's just a large sealed box... It behaves as any other sealed enclosure would.

2. If the amp is off there will be no bass to absorb 

3. Ya got me


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## Ayreonaut (Apr 26, 2006)

What I meant was "Does it behave like a bass trap?"

A sub that can stop on a dime will sound slow if there's little bass absorbtion in the room. Some bass traps are basically membranes which flex and dissipate the energy. 

An IB typically has a significant surface area and would probably do something in the way of soaking up that energy. The pressure waves in the room will push the drivers, and that energy will be absorbed by the suspension and will also generate EMF in the voice coil that is connected to the amp. 

Does this do much to absorb bass or practically nothing?


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## Darren (Apr 20, 2006)

Hm, I'm not sure it would do much in the way of absorption, especially if it is in the middle of reproducing subsequent frequencies as the previous dissipate. 

I think the major reasons an IB sound so clean and untainted is that there is no confining box or ports to color the sound and the nearly free-air movement of the driver makes it quick.

Just speculation mainly as I'm no expert. Just my observations....


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## Ethan Winer (Jul 21, 2006)

> Does an IB sub do much in the way of bass absorbtion? ... Would the absorbtion be different when the amp is on or off? <

A subwoofer that is not being used to play music at the moment could probably give a very small amount of bass trapping over a narrow range of frequencies. I can't imagine it could offer a _useful_ amount of trapping though. I don't know if it would absorb more or less with the amp on or off, but it probably would behave differently. With the amp on the cone's motion will be damped by the amplifier's low output impedance, and with the amp off the cone is more free to flop around.

--Ethan


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