Question on sealed box design and stuffing...

[Davey]

@DartmoorDad Understood. The mid-enclosure and tweeter are not relevant, but running the woofer up higher in frequency certainly is. In that case, you will definitely want to fill the box with an appropriate stuffing.

Dave.

 

[DartmoorDad]

running the woofer up higher in frequency certainly is. In that case, you will definitely want to fill the box with an appropriate stuffing.

XO is at 900. Tweeter XO to be determined on choice of tweeter... possibly a kef t15.

 

[keithj01]

Nah, the driver itself will have distortion levels considerably above the effects that might be reduced by stuffing.
A sub-woofer will be asked to do two octaves (at most) and will most likely have some serious low-passing above that.
A good driver and good construction techniques are obviously required. But stuffing is not.......for subwoofers.

Dave.

If the distortion products are significant, depending on the cabinet dimensions, cavity resonances will only make them more significant. Unless steps are taken to damp the resonances.

 

[Davey]

@keithj01 Have you got some relative distortion measurements you can post?
(Same driver/box....one stuffed and one not stuffed.)

Dave.

 

[keithj01]

No, but what I'm saying makes sense. Regardless of the source of the exciting signal, if it's at the right frequency, it'll be accentuated by cavity resonance.

 

[camplo]

The simulations include these degrees of stuffing: Minimal, Normal and Heavy.

"In the un-stuffed enclosure, we see a predicted Qtc of 0.924. In the enclosure with the minimal stuffing, the Qtc drops to 0.906. In the normal scenario, it’s predicted to be 0.837. Finally, in the heavily stuffed enclosure, the Qtc is a well-controlled 0.755."

I tried this in HornResp and did not get that dramatic of a change... I wonder what reality is. Personally I do not like Damping material, in the sense that if I can design for it to achieve something acoustically without it... I will do that route first... I am currently struggling with the idea that slot of PPSL woofers need damping to achieve the response I like.