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Down-firing Sub makes floor rattle

I just bought a ml dynamo sub. it is a great sub but it makes the floor rattle. i only use it for music so it is annoying..how do i fix this? i don't have it on the attached spikes as of yet....it is on the attached stand with rubber feet. would the spikes solve this? or should i just put something under the sub? this sub can also front fire, but i'd like to use it down-firing.......the carpet is very thin and maybe this is the problem?

thanks
cooch
newbee
4,767 posts
 
I think I've got some bad news for you. The vibrations that are being transmitted to your floor are more likely than not airborne, even that may seem counter intuitive. A down and dirty check - put your hand on the sub when its making the floor 'rattle' and see if the sub itself is producing a lot of vibrations. If not you might get some better help by shoring up the floor. JMHO.
shadorne's avatar
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shadorne
7,477 posts
 
Newbee has good point. Ultimately everything will rattle. A plywood sheetboard somewhere could use some extra screws perhaps? A lose air duct mounting? A heavier carpet or underlay may help too. Also try moving furniture around or put you hand weight on different things (touch windows/doors) - it might not be just the floor.
cooch OP
81 posts
 
thanks for the advice. i will try some more things...wouldn't front-firing the sub be better in my case?
flrnlamb
508 posts
 
Yeah, you're really not going to be able to solve this, other than balancing the sub out properly in the first place. Basiclally, down-firing, front-firing, slab, no slab, or even suspending the sub in mid air for that matter, isn't going to do anything about the airpressure and bassmodes in your room from being excited!!! Basically, unless you do something to your floor, it's going to respond accordingly. That's how bass works.
conversly, people think if they move their sub out from the walls, that it won't be as boomy in the room next to it. WRONG!!! That's not how it works.
Acoustics are what they are. You'd need to, like I say, just make sure you're sub is balanced out in level with your mains/the rest of the system (other than sub being way louder than the mains), and add some mass to your floor!
Good luck
cooch OP
81 posts
 
1 more thing....the manual says the crossover on sub should be set at 70% of main speakers lowest frequency...so if my speakers go down to 56 hz, the crossover on sub should be set to 39hz...does this make sense? that leaves a huge gap between where mains leave off and sub picks up...i am assuming martin logan knows what they are doing but this doesn't make sense to me....... what do you guys think?
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