Spikes versus Rubber on wood floor?

Fiddler, if this is what's happening in your case:

"All coupling does to many suspended floors is excite the floor which creates a delay in the sound traveling in the floor and it muddies the bass badly."

Then it's because the wood floor is flexing (what you call "excite") underneath the speaker allowing the woofer motion to rock the enclosure back and forth. Remember, it only takes 1/16" of deformation (flex) in the floor for a 5 foot tall speaker to rock back and forth as much as 3" at the top! There are three possible solutions:

1.) (the easiest) reposition the speaker so the front and rear spikes/cones/feet are on top of, or very close to, the (two closest) joists themselves (as discussed earlier)

2.) If (1.) isn't possible for some reason, then put blocking (little cross joists) between the two joists right under the speakers and/or put posts (or jacks) from the ground to under the floor where the speakers sit.

3.) If (1) and (2) aren't possible, the best solution (a bit of a hassle to do nicely, but works great!) is to run a brace (aluminum tube or plastic PVC pipe works well) from the top-back of the speaker to either the wall behind, or back down to the floor at least 4 feet behind the speaker, and secure it.

Any of these solutions will keep those woofers from rocking the cabinet instead of your ears. An additional benefit will be better highs and mid-range transients.

Hanging speakers can work also, except the chains or cables need to be splayed enough to insure that the speakers don't sway even a little. That's sort of an ugly tour-de-force don't you think?

Nsgarch, thanks for the feedback, but number 1, 2 & 3 won't work simply because the floor is being excited by certain frequencies. The problem is not floor flex, per se. The floor is acting like a drum head. It doesn't much matter where you strike the drum head, it will still resonate. Until the frequency vibrations are sinked to something with a much lower resonant frequency (such as, the ground or a concrete pad on the ground), they just rumble around until they dissipate. So moving the speakers over joists won't make a big difference. Believe me, I tried.

Stiffening the floor would cure the problem, but most effectively if it is stiffened by applying pressure from the floor to the ground, i.e. using floor jacks and posts or footings and pilings. These solutions simply change the resonant frequencies and the problem can be eliminated. But the simpler solution is to decouple the speakers. Do a search for actual results.

And according to other users, hanging a speaker from a single chain does not produce any movement of the speaker when the speaker is playing. I personally have no experience with this, but that is what has been reported from actual use.

Wellfed,

Now you've gone and done it, the Big Fat Dots are relatively inexpensive, so I suppose I am going to have to break down and try them. Still curious, how does the hardness compare with a hockey puck? Thanks, Tim

Fiddler, apparently you have a very under-engineered floor which is indeed being "excited" by the sound waves in the air! Is it an old structure? I have cured this problem for clients (I'm an architect) who had intolerably bouncy floors due to undersized joists put in by a shady builder (joists can be "up to code" to carry the load, but they usually need to be bigger than that to resist bending)

My solution in such cases (when none other was possible or practical) was to add a couple more layers of plywood subfloor, with the sheets staggered and edge and face nailed very well. This acts like a stressed skin and keeps the floor from bouncing excessively.

Frankly, I don't believe attaching the speakers elsewhere (like the ceiling) will keep the sound waves in the air from exciting the floor, as it is right now.

Nsgarch, I have a 3 year old home and I seriously doubt it was under-engineered. Apparently you are missing the point. I don't have a bouncy floor. I have a resonant floor. They are the result of the same problem, just a long way apart. When I walk on the floor it is not bouncy. But certain bass frequencies made it resonate when I had rear ported speakers. Now that I have changed speakers to OB's and a Velodyne DD12, I don't have the same problem.

However, with my previous speakers, when they were coupled to the floor they made the floor resonate badly. One of the reasons you are reducing the resonance of your clients floors is that you are adding mass, not just stiffness. The more mass you add the lower the resonant frequency.

There's no sense in us going round and round here. If you will just take the time to do a search, you will see the resonance problem is very common to suspended floors. And I am sure that all of the guys who have reported a similar problem here and on AA didn't have "under-engineered" floors.

"My solution in such cases (when none other was possible or practical) was to add a couple more layers of plywood subfloor, with the sheets staggered and edge and face nailed very well. This acts like a stressed skin and keeps the floor from bouncing excessively."

I can promise you that if you do a search you will find a very "possible and practicle" solution to the problem other than the expensive, time consuming and unnecessary fix that you employed.

And I appreciate the fact that you are an architect, but when I built my business, both I and my contractor found many practical, economical and more effective methods of doing things than my architect had drawn and submitted. Any good contractor with a lot of real-world experience will take virtually any plan drawn by an architect and improve it. No intentional slam here, but like I said earlier, give me actual experience any day.