[atledreier]

Hi!

After finally getting a good calibration on my system, I have a new 'problem'. In bass heavy sequences my sonotubes literally jump on their feet, and cause a racket. The feet I used are a little flimsy, so they make a little noise as well. I have felt cushions under the feet against the floor, but still the subs are much quieter when I put some weight on them when playing. What do you guys use to keep them on the floor?

For the record they are Soundsplinter RL-p15 LLT tubes.

 

[tonyvdb]

I know some people have filled a section of there sub with sand for the added weight.

 

[atledreier]

Not really a doable solution with a bottom mounted driver in a tube.... But keep em' coming.

 

[looneybomber]

Can you add more MDF to the base plate, baffle, or top plate? What you need is more weight, but metal spikes may also work?

 

[atledreier]

The subs are done, primed and painted, I just haven't really used them before. I don't have a baseplate. I might go with sorbothane under the feet, maybe changing the flimsy feet for something more heavy duty. Looks really don't matter much, they are behind curtains in my theater...

 

[tonyvdb]

So your saying that they have no baseplate, Why not build one that is the same diameter as the tube this way your feet are attached to that giving it better support and is actually better for sound output particularly if you make the base a slight cone shape.

 

[tenzip]

Or get a baseplate made out of 3/4 or so steel. A metal fab shop that has stock in that thickness should be able to cut it out for you, and even drill holes for your legs to attach to. Shouldn't be terribly expensive.

That should be enough weight to hold it down, just don't drop it on your toes.

 

[atledreier]

There's gotta be hundreds of these constructions around this forum. None of you have this issue?

 

[tonyvdb]

There's gotta be hundreds of these constructions around this forum. None of you have this issue?

The lack of a baseplate is a huge attributer to why your sub "bounces" once you address this it should all but stop.

 

[atledreier]

What's the theory behind that? It's not much added weight, compared to the rest of the construction. I'm not doupting you, I just want to understand WHY.

 

[tonyvdb]

Its simply the force of the air and the low frequencies that the driver is pushing down on the floor instead of the plate if you have a plate the air is forced out the sides rather than onto the floor and then out. How much of a space did you allow for between the floor and the driver?

 

[atledreier]

About 6", 16cm. Should be plenty. SO you're saying the force of the air downwards will counter the upward force of the driver through the legs.. Interesting. Makes kinda sense, although I'd have thought the actual force from that air or pressure wave would be a lot less than the force of the moving driver. I've been proven wrong before, though! I'll get som baseplates done in the near future, I need my reference levels!

 

[tonyvdb]

About 6", 16cm. Should be plenty. SO you're saying the force of the air downwards will counter the upward force of the driver through the legs..

Yes 6" should be more than enough, once you have the plate mounted to the bottom of the legs you will probably notice that you can get even more out of your subs. Looking at your post on the construction of your subs I can see why they are moving, Thats quite a large driver in each and most certainly has the capability of moving the sub around without the base.

 

[atledreier]

I can do calibrated reference levels for all the movies I've tried so far, including the LFE killers, so I don't really think I need more, but keeping them quiet is another issue altogether. How do people usually mount these baseplates? Right now I have the legs mounted to the bottom. They need to go. Is there a solution that will allow me to mount some legs withought opening the subs and removing the driver?

Time to dig up some old build threads, I guess...

 

[tonyvdb]

How do people usually mount these baseplates? Right now I have the legs mounted to the bottom. They need to go. Is there a solution that will allow me to mount some legs withought opening the subs and removing the driver?

Time to dig up some old build threads, I guess...

Not sure what is the best idea but what I would think should work is some 6" lengths of thick dowel (maybe 1.5" diameter). For the baseplate you can simply use some 1" MDF with holes drilled 3/4 of the way through where the dowels can fit into and screw them in place. for the bottom of the tube maybe just glue some pieces of 1" MDF to the base that have the holes for the dowel in them and glue them in place as well.
But maybe someone else has a better way as I'm no expert:hide:

 

[thxgoon]

Right now I have the legs mounted to the bottom. They need to go. Is there a solution that will allow me to mount some legs withought opening the subs and removing the driver?

Why do the legs need to go? I cut a piece of MDF the same diameter of the bottom plate and drilled through it into the legs from underneath and recessed the screws. So far it has worked fine.

It looks like I didn't take any good pics of it during my construction but maybe this page would help.

 

[atledreier]

My current legs need to go as they are flimsy and rattle. I should take the drivers out and put some batting in there as well, I think. I've been toying with the idea of just making brand new enclosures now that I've learned what NOT to do.

 

[MatrixDweller]

I'm sure the air and also the movement of the cone could cause a sub to jump. The sub will sound better if it doesn't move at all. Best options are to make a baseplate out of 3/4" steel or use some granite or marble. You could probably sandwich two or more 12"x12" granite tiles together. You might be able to find some on sale at a big box store for under $5 each if you're lucky.

Another idea would be to get a slightly larger sonotube (~2" wider in diameter) to go around the existing sonotube and fill the gap with sand or cement (without stones). That's if you're going to rebuild the enclosures. That would probably weigh it down a good 50lbs or more.