aperiodic vent

[Stew320]

Hello all,

I have been presented the task of building a sub for music reproduction. My plans are to use an Adire Tempest. a 200 litre enclosure is my limit on size.

This gives a Q of .61 which is not as low as i'd hoped. the target is more like 260 litres for Q .59.

Option A, Question: how much will fibreglass loft insulation increase the apparent volume?

Also i read a while ago somewhere that "stuffing" a box can detract from sound quality regardless of the lower Q, anyone herd anything about this?

Option B, Question: how do you go about designing and building an aperiodic vent? is it a case of making a fibreglass/steel mesh sandwich, then mounting and sealing it over holes say on the underside of the enclosure?

I also read somewhere a while ago that this is preferable to option A and even has some benefits like raising and flattening impedance?

Cheers

Stew

[GM]

It varies with frequency and loading, but 1.2x is a realistic average. Here's some measured results of various densities in sealed and vented: http://www.integracaraudio.com/carau...ces/fiberfill/ and a brief write-up on stuffed vented: http://www.geocities.com/kreskovs/Box-1.html

Aperiodic alignments can be simmed with any program that allows you to adjust Ql (box frictional losses) and/or Qp (vent frictional losses).

GM