Vibration Damping or Acoustic Damping for Sealed Sub?

[88man]

Should one use any vibration and/or acoustic damping for a sealed sub?

I made a sealed sub box for a LMS 18" sub. 2" Front baffle, 1.5" all other sides. Internal volume is 4.1 ft^3. I'll be using a Cerwin Vega CV-5000 amp. Cherry Veneer on MDF. Sanded to 400 grit, ready for staining. Will use 3 coats of Sam Maloof Oil/Poly then 8 coats of Arm R Seal Oil/Poly as necessary.

Thanks

 

[sreten]

Hi,

stuffing should work, depends on the driver.

rgds, sreten.

 

[moray james]

if your panels resonate within the intended bandwidth of the driver then your cabinet should have been braced, you could always add some brace work if necessary to force panel resonance up an octave or more and that should cover you. So long as the cabinet resonance is above the desired bandwidth of the drive there should not be much issue.

 

[88man]

Thank you, sreten and moray! I'll have to determine how to calculate panel resonances. When in doubt I guess I can simply add bracing, if 1.5" thick walls are not enough.

 

[Shadydave]

Install the driver and see if there is any panel flex.
Crank it up and feel the box walls.
If they are not vibrating heavily, your box is probably fine the way it is.
The box that you built is much more beefy than most.

The only bracing that I can see you being able to install at this time is hardwood dowels.
You run them from one side of the box to the other side, but they have to fit perfectly to work.
I use 1" or 1-1/4" Oak dowels that I buy from Mc Master Carr.
Even those may not fit through the driver hole easily.
And it is best if you put a long screw right into each end of the dowel to help the glue.
That wouldn't bode well with your beautiful veneer job.

Also, keep in mind that it sometimes takes months to break in a driver, IE loosen up the suspension.
They sound better and better as you use them.
I noticed differences in a set of Infinity 1260's for a half year.

Dave

 

[NEO Dan]

You can still use pocket screws to secure bracing from the inside, I would go with something like hardwood flooring slabs as MDF with pocket screws are likely to blow out the pockets.

 

[bjc]

To test the box if you think it's not sturdy enough you can get your large clamps and clamp the sides and top/bottom of the box to see if there is any improvements when running sweeps or pushing the sub hard!
I have always done the inch dowel like Shadydave has mentioned in my previous sub boxes that have already been built or my manufactured speakers that could benefit from bracing. Either that method or run 1x1 inch lengths along the middle of the inside walls and glue them in place to minimise flex...