Subwoofer Mounting / Feet?

I have an SVS cylinder sub in the corner of my room. Bass is great, but the room has a wood floor so it can "rattle" a bit on its small feet. I put some pressure on top of the sub (with my hand), but it just seemed to slow down the rattling, making the whole subwoofer "hop" a few mm at a time instead (yes it was turned up fairly loud).

Any suggestions of a better way to mount it? Thought of just putting something softer under it but I didn't know if that would cause me to lose bass. I could build something and bolt it to the floor I guess...

Thanks.

You could try spikes. I have an SVS sub on a wood floor and don't have the problem.

Ask the SVS people, they're good with answering questions.

The thing is your sonotube wants to hop around. I've never had a sonotube sub, but...I'm not sure spikes will do anything but put millions of holes in your wood floor! I would get a slab(s) of marble, granite or even paving stones to keep it from hopping.

Ineresting that you have the hopping sub and zacster doesn't...

My SVS 25-31PCi is on a hardwood floor with just the standard feet and it has stayed quite still (although I can't say the same for some knick-knacks in the vicinity...). The idea of a slab of something heavy underneath is a very effective for vibration isolation, but I don't know if it'll stop the sub from hopping unless you are getting floor movement of some sort. Zacster's right, SVS can probably square you away one way or the other.

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You can try putting "Blu-Tack" putty under each foot. I use earthquake putty in my room under stuff and behind pictures and it keeps them from rattling. It may keep your sub from moving.

Correct me if I'm wrong but I've been under the assumption that anchoring your sub to a hardwood floor via spiked feet will substantially lower the "quality" of the bass output. It seems like isolating it with something like the granite slab mentioned would be the better alternative

I use a product called the "GRAMMA" that's made by Auralex Acoustics. It isolates my subwoofer from the floor very nicely. It costs $50 and you can find it either online or in most Pro Audio Stores.

www.auralex.com/sound_isolation_gramma/sound_isolation_gramma.asp

Good Luck!

Using spikes does isolate the subwoofer from the floor; that's the whole point of them (no pun intended), AFAIK. It creates a very small path for the sound waves to be transmitted through to the floor.

I would think the granite does the same thing in a different way. Instead of isolating the sub from the floor, its large mass absorbs the soundwaves, preventing them from reverberating in the floor.

I'm sure the experts will tell me if I got this all fouled up, but this helps me justify using floor spikes, anyway

-Joe



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FYI:

All custom granite countertop fabricators routinely toss tons of granite pieces (sink and cooktop cutouts, remnants, etc.) of every type of granite.

A visit to one of these shops should yield as many pieces of granite as you can haul for free, or you can pay them to put a nice edge on one.

Pardon me if I oversimplify, but some underlying principles before I comment ...

In most subs, you have one or more drivers pushing air in large amounts at low frequencies. Unless you have perfectly matched multiple drivers arranged to produce exactly the same motions in a way such that they cancel each other out within the frame and cabinet of the sub, there will be a moderately complex set of equal-and-opposite energy reactions that result in vibration of the non-driver components. Some of this extraneous vibration energy may transfer to the air, some will travel into other objects via whatever ‘feet’ there are. Other than what is lost to friction/heat, the mechanical vibration energy MUST go somewhere.

There are two simple extremes to handle this vibration. One, the cabinet’s vibrations are almost totally isolated from the floor, usually by something with ‘give’ in it. Two, couple the cabinet solidly to something that dampens the cabinet vibration. A third ‘hybrid’ option is to couple the cabinet to something that dampens the vibration while isolating both the cabinet and the dampening mass from the supporting environment.

In case one, extraneous vibration of the cabinet will transfer some additional acoustical energy into the air directly. The type and size of cabinet will determine whether this is detrimental or nearly inconsequential. Spikes are an instance of the second and third situation. Much like a bridge on an acoustic string instrument, this small device will facilitate, not hinder, the transfer of mechanical energy from one object to another. That is why the cabinet will vibrate less – the spikes have allowed some mechanical energy to be transferred somewhere else. If the object on which the spikes rest can act as a somewhat efficient sounding board, the mechanical energy transferred will become acoustical energy. Spiking the sub to ‘brick,’ or other material that resonates poorly at the frequencies concerned, on top of ‘pad,’ with some give in it at the appropriate frequencies, perhaps in multiple layers for various frequencies, is a principle used in both some DIY and professionally fabricated products.

I have ‘sound board’ wood flooring, so I make some effort to isolate my loudspeakers from the flooring. I am not into expensive, exotic solutions, however. Why? Even if I were able to completely dampen, isolate and prevent loudspeaker mechanical energy from directly reaching the potential ‘sound board’ surfaces in the room, these surfaces will vibrate once affected by the vibrating air. Room acoustic treatments are another topic.

Sorry for the long-windedness. Put reasonable effort into solving problems you find, but then sit back and enjoy!


[This message has been edited by bestbang4thebuck (edited November 11, 2003).]

bossobass,

Your granite "sink hole" solution is exactly what I have advocated in other threads for use under turntables.

However one thing to note about this approach: you need BOTH mass (granite) and an acoustic insulator for it to work properly. I suggest two slabs of granite sandwiching a layer of rubber. Those non slip workshop mats (that come in rolls) work well. Just fold it to get four layers. You can even sit the speaker on another layer of mats (both for additional isolation and to keep the speaker from "dancing" on the polished granite.

Regards.

Jeff Mackwood

I have my SVS sub on a carpeted floor and it sounds fine to me. Perhaps I am missing something since I never had it on any other surface. (may try moving it a few feet over to the marble floor in front of my fireplace later to see if I can tell the difference.) Wouldn't a throw rug do the trick ?

I think most have missed the point, his sub doesn't move, it rattles. The sub only moves if he pushes down on it. I own an SVS sub and have never experienced this, the cylinder shape is so rigid over braced cubes, that it can't rattle. Since this sub fires down at its own wood platform, (its feet are attatched to this platform so the driver does not fire directly at the floor), see if the platform is securely attatched to the sub. If the platform is loose, this might cause the rattle. Are the feet tightly attatched to the platform? Is your floor braced in this area? Put a throw rug under the sub and see if the rattle stops. Are your floor boards level under the sub? Let us know how you make out.