The Vibrator

[snap08]

I thought id get more attention with a catchy title

anyways i have my sub mounted now and inverted with the polarities opp to the DVC.

my box is still sealed and the back wall (its a mod. wedge) vibrates like an s.o.b.

im going to port the box through the top of the box, so will this relieve pressure and stop the vibrating. i just dont want to cut open a perfectly good box and it ends up sounding bad. or what are some poss. bracing ideas.

thanks

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[indosia 10+ year member]

If you port the box it will increase vibration. You need to add damping matirial to reduce vibration.

 

[bean 10+ year member]

Don't do anything more. Box building is a science. You don't just put a hole here or a port there. And this, "Relieving Pressure?" Who told you to do that? A port in an enclosure has a very specific function. Usually the enclosure needs to be larger than a sealed one. The port needs to be a specific length and diameter. The enclosure is the MOST important part of the sub woofer system. From what you've described, you might as well take a **** in a box and plug that into your amplifier. You'll get the same response.

 

[snap08]

mabey i did a bad job explining my self but u dont have to go cutting my head of and shittting down my throat.

my box design is within the spec sheet size for both the ported and sealed box and i know what size to make the port (3"*12") . i ust never had a box vibrate like that b4.

anways since your are the box genius what is the best material to use to stop the box from vibrating.

 

[bean 10+ year member]

Use a medium density fiberboard (MDF) 3/4 to 1" thick. It'll cost you about 25 or 30 bucks for a 4X8 sheet.

 

[EVOECLIPSE 10+ year member]

actually i would try and spray some sound trunck liner on ther first. you can get cans od "rubberizer" at walmart for about 2 bucks each. and i am a firm believer in ruberizer. my buddie had a lot of ratting going on in his trunk and we sprayed the whole thing with rubberizer. and it stoped most rattles. and it also increased the loudness.

 

[chris229 10+ year member]

guys----damping mat OR spray isn't going to do anything to HEAVY wood. bracing the box is the answer------bean has the answer reguarding just THROWING a port in

 

[indosia 10+ year member]

Any increase in mass will reduce the vibration. Although, if the box was poorly built you should build a new one. use .75 inch mdf. pre drill screw holes. use 2 inch long wood screws every inch where the boards are joined. Use lots of would glue and apply calk to the inside.

 

[chris229 10+ year member]

Originally posted by indosia Any increase in mass will reduce the vibration.

yea true but for--- WOOD---- mat or spray ISN'T going to be effective for adding weight. THe mat or spray will only add a couple of ounces to the HEAVY wood. To be effective for wood you sould be adding many pounds------lead or granite wood be a more effective mass adding source----as wood weighs so much already. Mat is good for light metals that only weigh a couple of ounces to begin with. bracing would be a better way to add dampng

 

[Alaxan 5,000+ posts]

Brace it! Depending on the material you have used hopefully it was MDF already, make sure your screws are nto too far apart. Make sure they are all tightened down. Pull out the speakers and make sure the box has been sealed properly and nothing is leaking! Sometimes small air leaks in a box can make it sound like rattling. Also sometimes poor design can make it have that effect.

 

[bean 10+ year member]

FYI, the screws are not what holds an enclosure together. Wood glue does. The screws simply hold the MDF in place until the glue dries. Don't believe me? Glue two pieces of MDF together (at the ends just like a sub box). Once it dries, break the joint. What broke the wood or the glue?

 

[chris229 10+ year member]

Originally posted by bean FYI, the screws are not what holds an enclosure together. Wood glue does. The screws simply hold the MDF in place until the glue dries. Don't believe me? Glue two pieces of MDF together (at the ends just like a sub box). Once it dries, break the joint. What broke the wood or the glue?

I've seen glue fail many times. You can't go without screws

 

[Alaxan 5,000+ posts]

Hey bean I am surprised you are even giving suggestions for anyone to do anything on their own? Yes I am aware of how the glue holds and works, but I am also aware that screws hold as well and that you can not put the box together without them and you will very NOT likely get a good seal if you do unless you waste an ass-ton of time clamping and waiting.

 

[bean 10+ year member]

Any increase in mass will reduce the vibration. Although, if the box was poorly built you should build a new one. use .75 inch mdf. pre drill screw holes. use 2 inch long wood screws every inch where the boards are joined. Use lots of would glue and apply calk to the inside.

Sorry, didn't mean to imply that wood glue is the save all. I just saw this quote and thought that putting a 2 inch screw every inch was way too much.

 

[indosia 10+ year member]

Originally posted by bean

Sorry, didn't mean to imply that wood glue is the save all. I just saw this quote and thought that putting a 2 inch screw every inch was way too much

Too much will ensure the box never bends, flexes, vibrates, or falls apart. A subwoofer is constanly pounding causing lots of stress on the enclosure.