HELP- Tower Speakers Rattling Hardwood Floors

[corymat]

I recently bought a Definitive Tech surround sound system anchored by a pair of BP7004 Floorstanding speakers (which each have the built-in 10" subwoofer).

The problem is that I have an old Pier and Beam foundation house with hardwood floors and when the bass gets low, it's completely drowned out by the rattling of the floorboards.

I'm currently using the feet that came with the speakers, not the spikes. Will spiking the speakers on a hardwood floor do any good? I'm assuming I'd have to go buy the disks to place under the spikes, but is it even worth the time?

Thanks for the help.

 

[WmAx]

I recently bought a Definitive Tech surround sound system anchored by a pair of BP7004 Floorstanding speakers (which each have the built-in 10" subwoofer).

The problem is that I have an old Pier and Beam foundation house with hardwood floors and when the bass gets low, it's completely drowned out by the rattling of the floorboards.

I'm currently using the feet that came with the speakers, not the spikes. Will spiking the speakers on a hardwood floor do any good? I'm assuming I'd have to go buy the disks to place under the spikes, but is it even worth the time?

Thanks for the help.

The only way spikes will help is if the feet of the speaker are not all contacting the surface evenly, giving you a poor contact, but that is slight, which has a particular resonant frequency that is being excited. The spikes, if adjustable, will allow you to even out this contact to prevent this effect. Alternatively, use some card stock to wedge under the foot[feet] that have poor contact. If the noise in question is the actual floorboards/structure, you must decouple the speaker from floor mechanically. A spike will not do this; a spike couples the object. Mechanical isolation can be difficult if cosmetics are important, because you may have to build a custom solution. If cosmetics are not important, you can easily isolate the speaker by using the following Auralex product:

http://www.auralex.com/sound_isolation_gramma/sound_isolation_gramma.asp

-Chris

 

[saurabh]

Try using a rubber floor mat and put it below the speaker. It might just work.

 

[Buckeye_Nut]

Is the speaker rattling where it touches the floor, or are the floorboards themselves rattling?

 

[corymat]

I haven't really gotten down and put my ear there when it rattles, but my previous system had a downward firing subwoofer which caused a bit of the same problem (part of the reason I went with side-firing subwoofers). I'm almost positive by the sound is the floorboards, though.

Unfortunately, cosmetics are an issue so my initial thought was the spikes would raise the bottom of the speakers away from the floorboard at least another half inch and that would maybe give enough breathing room between the actual speaker cabinet (which lies above floorboards that are easily a good 4 feet off of the actual ground). Right now, even with the provided feet, the speaker isn't much more than a quarter inch off the floor at the most, which seems pretty close to the floor for a subwoofer (to me), even a side-firing one.

Am I fooling myself thinking this will make a difference?

 

[WmAx]

I haven't really gotten down and put my ear there when it rattles, but my previous system had a downward firing subwoofer which caused a bit of the same problem (part of the reason I went with side-firing subwoofers). I'm almost positive by the sound is the floorboards, though.

Unfortunately, cosmetics are an issue so my initial thought was the spikes would raise the bottom of the speakers away from the floorboard at least another half inch and that would maybe give enough breathing room between the actual speaker cabinet (which lies above floorboards that are easily a good 4 feet off of the actual ground). Right now, even with the provided feet, the speaker isn't much more than a quarter inch off the floor at the most, which seems pretty close to the floor for a subwoofer (to me), even a side-firing one.

Am I fooling myself thinking this will make a difference?

The spikes will just couple it to the floor to a greater degree. First try to wedge under the feet to see if it's just that a foot or two is not making even contact. Use some of the felt bottomed furniture feet to be sure. If this does not solve the problem, you will have to find a way to mechanically uncouple the cabinet from the floor structure.

-Chris

 

[ScottMayo]

The spikes will just couple it to the floor to a greater degree.

I agree. If it's the floor itself rattling, spikes won't help. Nailing the boards down more firmly probably will; if you can get under the floor, caulk where wood meets wood may also help.

Putting large, soft rubber feet under the sub may help some - the sub's sound will be less accurate that way, but for most subs that doesn't much matter. Try putting the sub up on 4 thick phone books - it may help a little, and may help point to where the problem is.

 

[WmAx]

Putting large, soft rubber feet under the sub may help some

Not likely with the standard rubber feet typically sold. Standard rubber feet will be too stiff, thus have a resonance point that is above the bandwidth of the sub-woofer. They will act virtually as solid coupling devices; some uncoupling effect may be possible, if it is a very soft rubber, and is partially compressed, but not flattened under the sub-woofer weight. For proper uncoupling using a readily acquirable product, a rubber sleeve with metal threads molded into it(I forget the proper name) may work well, as if you match up the weight of the speaker with a set of these of appropriate specifications, it will act as a buoyant suspension of relatively low frequency. These are available at larger farm hardware supplies. I am not sure if Lowe's or Home Depot carry these as standard items. One could also use foam blocks under the speaker, but a very specific stiffness would be required to prevent bottoming out, but still allow a floating effect.
.

- the sub's sound will be less accurate that way, but for most subs that doesn't much matter.

This appears to be a myth that has perpetuated. I don't know of any substantial evidence to back it. A related consideration is if the speaker is extremely light, compared to the mass and movement of the sub-woofer cone. Combine this with a particularly nasty resonant mode of the feet coupling to the floor poorly, and it may be possible for the cabinet to physically move under the right circumstances. Some sticky rubber between the floor and feet/cabinet would render this a non-issue.

-Chris

 

[corymat]

Thanks for all of the advice, I'm going to try the options suggested this weekend and see what works the best. I'm hoping I don't have to buy a riser to put under the speakers, but if that's what it takes...