Damping a WAW / FAST cabinet

MrJolly

Member
2014-04-23 9:54 am
Been reading various posts on the subject of damping and, as usual, i'm finding a lot of different opinions.

My setup will be an Alpair 12p in a 10L sealed sub-enclosure (stuffed) and a 12" Dayton woofer in a 100L cabinet, ported and tuned to roughly to 30hz. Drivers are crossed 1st order at 300hz,a few questions:

  • Apparently, due to the extended wavelength from < 300hz damping isn't all that effective and bracing is much more essential, will that be the case for my setup?
  • I've tried to retain as much cabinet volume as possible, when adding damping material am i losing cabinet volume or does it act as additional volume in the way a sealed enclosure would?
  • If damping is needed, how much and where would it be best placed?

Thanks in advance for any info :)
 
IMO and that's all it is.... :)

For the 12" TL, build it out of 1" ply and brace it a couple of times down the line. Folding the line will help rigidity but only in one plane. Consider building "T" type bracing into the line front baffle and rear walls and brace them together. Consider the effect on line volume in your design.

Damp the FR box with proper felt
Loudspeaker damping materials for DIY speaker kits.

Stuff the FR box with wool or MDM2 or MDM3 (from CPC?). Wool should be better but other products can be cheaper and more available.

For the TL, assuming a well built and rigid box, felt the areas around the loudspeaker itself and stuff the line with wadding to tune the response. Usually, the mantra is less stuffing is (usually) better.... But anything I've read refers to TLs in a full-range capacity.

J.
 

Destroyer OS

Member
Paid Member
2005-11-14 11:09 pm
PNW
I disagree. All internal reflections put pressure on the come that have negative effect. Reducing them and softening them is important. But I've only had luck with no-rez. Poly fill was very bad when I tried it. Perhaps it works in certain areas away from fullrange driver.
 
Sorry, should have been clearer with my question - it's actually a standard reflex cabinet, not a TL.

D'oh! I have TLs on the brain. For a BR sub, brace/damp the walls and add stuffing whilst keeping a path clear between the driver and the port.

Less stuffing = more cabinet resonances but higher overall output.
More stuffing = less resonances but lower overall output/efficiency

I have seen a reasonable article demonstrating the effects in a sealed box but of course, being the internet, I now cannot find it. :(

Also found some subwoofer article where they used actual whole pillows inserted into the cabinet.
 

MrJolly

Member
2014-04-23 9:54 am
D'oh! I have TLs on the brain. For a BR sub, brace/damp the walls and add stuffing whilst keeping a path clear between the driver and the port.

Less stuffing = more cabinet resonances but higher overall output.
More stuffing = less resonances but lower overall output/efficiency

I have seen a reasonable article demonstrating the effects in a sealed box but of course, being the internet, I now cannot find it. :(

Also found some subwoofer article where they used actual whole pillows inserted into the cabinet.

Thanks for the update :)

Efficiency isn't a massive concern at the moment - unexpectedly the bass driver could almost use some attenuation so i'll have a play with what you've suggested above and see what i get.

Cheers!