Subwoofer Vibration Elimination

[Ornlu]

Ok, well I built a subwoofer enclosure recently and one of the only problems is my tile floor.. the sub doesn't like sitting on it.. And I'm too cheap to buy spikes / want to try my own solution.

 

Basically, think those long cables used to tie crap down on the car roof... bungie cables or however it's spelled.

 

Think it will work better ot worse than spikes?

 

The whole sub (1.85 cubic foot exterior would basically just sit on that) It'd be pretty easy to build.. I have so much extra MDF sitting here..

 

[Waco]

You mess up the sub's transient response and output levels with that. The enclosure needs to be rigid, and if you put it on those bungie cords it's going to dampen the movement of the subwoofer to some degree. If you don't like it rattling at the very most I would put it on a small piece of carpet.

 

Spikes are still the best solution.

 

 

EDIT: Your sub enclosure shouldn't be flexing enough to cause rattles anyway, if you have a bunch of MDF laying around I'd suggest bracing the enclosure internally a bit more.

Edited July 17, 2005 by Thewacokid

[Ornlu]

I don't see how it would mess up the transient response of the sub, The cone movement is of so little mass that it does not displace the near 60 lbs of the box in a horizontal motion parallel to cone movement. Most vibrations are unrelated to accoustical output and more related to mechanical vibrations of the structures resistance to the driver moving. the transient response shouldn't change as the accoustics of the box itself remain identical. It's like holding the sub in the air.. instead of mechanical energy being lost to the floor in the form of unwanted vibratings it's lost to bungie cords... There's really no difference. It's not like the cone's going to stay in one place and the box is going to move back and forth on the cords...

 

Edit: The vibrations aren't due to the box's structural integrity. It's double braced inside and has a double thick front. It's sealed too, air tight. The vibrations only occur at > 105 ish db output Big explosions in movies.. the few instances when I have it turned way up. The vibrations only become AUDIBLE at this point. And it's not the box making noise but beams under the floor that aren't braced properly and are bothered by the small vibrations present when the box hits 100 dbs and up at 20-30 hz.

 

I'd rather have these vibrations only be in the air than in the floor as well. Which might not be possible.. it might just be the waves themselves causing the vibrations. But I figure this should help.

 

To sum it up, it's not a problem of the box as there is absolutely NO noise except for the bass if I'm holding it up in my hands. Which is quite the task.. lol..

[AntitrustSpider]

You do realize that the wood would probably make more noise on the carpet then the enclosure. I suggest just going and getting some rubber feet for the enclosure.

 

I also suggest just putting something between the box and the subwoofer where it mounts, and screw it down as tight as possible. It could also be that your subwoofer just can't handle the power, and is just making funny noises.

[Ornlu]

You do realize that the wood would probably make more noise on the carpet then the enclosure. I suggest just going and getting some rubber feet for the enclosure.

 

I also suggest just putting something between the box and the subwoofer where it mounts, and screw it down as tight as possible. It could also be that your subwoofer just can't handle the power, and is just making funny noises.

510964[/snapback]

 

It's not that... It's got a rubber seal and is air tight.., and the sub can handle extremely high currents I'm not even touching the excursion limitations. the sounds aren't coming from the sub, that's completely silent (mechanically). The sounds are coming from inside the floor behind the wall that the sub is 1 foot away from.

 

Right now it's on a towel folded 4x, it's not bad.. I'd just rather isolate the sub from room vibrations entirely.

 

And I don't think the wood will make more noise with a highly dampening material (bungie cord) inbetween it and the enclosure than the wood of the enclosure Directly on a tile floor.. Let's use common sense atleast. The vibrations are minimal and only emphasized by the fact that the whole thing weighs a hefty 65 lbs.. So every bit of that vibration is translated directly into the floor.

 

 

Just to clarify, the sub enclosure will rest on the bungie cords ONLY it will not touch the wood of the bottom base shown in the pic above. So all vibrations will be translated to the bungie cords, with minimal vibrations being transfered to the wooden base.

[jammin]

I would suggest trying out your design if you can build it for nothing to see if it gives you good results.

We can theorise all day about what kind of effect it would have, but just doing it will be the only way to find out.

If it doesn't really help, then spikes aren't really that expensive are they.

[Silverfox]

i have a problem with my sub on the carpet...so a built a ghetto cradle out of some thick 3-core cooker electrical wire and hung the subwoofer in the cradle underneath my desk. i caused less vibration through the floor and sounded marginally better as well.

 

i agree with jammin - every room is different and you should try out a number of combinations to find what's best for YOU and your room. also, its worth finding out what is best for the type of music you listen to.

[hardnrg]

Edit: The vibrations aren't due to the box's structural integrity.  It's double braced inside and has a double thick front. It's sealed too, air tight.  The vibrations only occur at > 105 ish db output  Big explosions in movies.. the few instances when I have it turned way up.  The vibrations only become AUDIBLE at this point. And it's not the box making noise but beams under the floor that aren't braced properly and are bothered by the small vibrations present when the box hits 100 dbs and up at 20-30 hz.

 

I'd rather have these vibrations only be in the air than in the floor as well.  Which might not be possible.. it might just be the waves themselves causing the vibrations.  But I figure this should help.

 

To sum it up, it's not a problem of the box as there is absolutely NO noise except for the bass if I'm holding it up in my hands. Which is quite the task.. lol..

510944[/snapback]

 

it's your sub hitting the resonant frequency of the floorboards... not much you can do about that except either moving your sub to somewhere where the floorboards don't have the same resonance problem... it is, as you suspect, the sound waves in the air that cause this and you either have to fit sound dampening rubber washers and bolts to the thing which is vibrating (floorboards) or nail/screw them so secure that they don't rattle when they vibrate...

[Ornlu]

Yeah, I was a fraid that's what was happening.. Resonance is annoying. But I still want to reduce the vibrations transmitted.. So i figure I'll jsut try it.

 

The sub is extremely tight and musical, it's less of a home theater sub, although it can drop into the low 20's no problem.

[hardnrg]

the fortunate thing with subwoofers is that it doesn't really matter where you have the sub in the room as the relative position to the listener isn't critical. the position of the subwoofer to walls or other solid objects affects the resulting sound as the side effects produced can include resonance of other objects and uneven bass over the room from constructive/destructive interference from standing waves in the room...

 

Subwoofer Placement

 

basically it may come down to experimenting with the placement of your sub to eliminate resonant object vibration, but because the sub is somewhat omni-directional you have a fair amount of leeway in the number of options that will work...