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Howard 20th March 2005 06:29 PM

Wadding / stuffing
Would adding some acoustic wadding to the inside of a ported subwoofer make any difference to the sound?

How would it affect it?


crippledchicken 20th March 2005 09:15 PM

Re: Wadding / stuffing

Originally posted by Howard
Would adding some acoustic wadding to the inside of a ported subwoofer make any difference to the sound?

How would it affect it?


hi Howard, usually ported subs don't benefit from stuffing nor, is it needed due to such a low crossover point. from what i've heard, good bracing is important though especially, on large enclosures.


Volenti 21st March 2005 08:19 AM

Stuffing damps resonance, this is not always easily heard but it's effect is easy to measure (drivers impedance at resonance is reduced (damped)).

Since a vented enclosure more or less works by resonance stuffing it will reduce output, this can be helpfull if the tuning is too high and it has a peaky/boomy sound but is otherwise detrimental to performance.

ie; if it sounds bad try stuffing it, it's an easily reversable tweek.

bremen nacht 8th January 2006 01:29 PM

What about in a full-range ported cabinet? The cabinets I'm building are 100 litres, and I'm going to control panel resonance with plasterboard and much bracing, should I also be using wadding and if so how much and where?

Crossover is 1kHz and th edrivers are Tannoy 12" HPDs.

Volenti 8th January 2006 11:00 PM

I'd line the walls with about 1'' thick sheet wadding and double or triple up the thickness directly behind the driver, massively complex bracing can also have a damping effect and help to break up standing waves also.

simon5 9th January 2006 06:28 AM

Stuffing a ported subwoofer will lower the tuning point because the box will be acoustically bigger. You could cut the pipe a bit shorter to counteract this.

Collo 9th January 2006 08:50 PM

Damping in ported subs
I use damping in ported subs, only where I need to control standing waves.

Usually the problem is the longest dimension on a tall box, so I use foam sheet on the top and bottom surfaces, which are zones of high pressure. For a deep box, I line the back panel as well.
Note that since the velocity at a wall boundary is zero, there is no advantage in using acoustic wool on the walls

The centre of the cabinet is a zone of high velocity, so I make sure I design in a shelf brace which has acoustic wool stapled across the cutouts.

I also ensure that the wool is not between the port intake and the driver - I don't want to lose any energy from the port. ;)


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