Spikes versus Rubber on wood floor?

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.

Fiddler, I am an experienced builder as well as a licensed architect. I also have a minor in acoustics from MIT, and trust me, you don't begin to know whereof you speak, your limited personal experience notwithstanding. There are architects and architects; sorry you didn't find a better one.

As for your resonant floor, speakers coupled to the floor can't possibly move the floor for the simple reason that, except for down-firing subwoofers, transducers only move horizontally and floors only move vertically. So whether you say 'bounce' or 'resonate,' the floor would have to move; and if it doesn't, then perhaps the floor isn't the culprit; it could have simply been a standing wave between floor and ceiling created by an identical frequency peak in your previous system's response curve.

My guess, after all you've described, is that your new system's response is such that the natural room oscillation (standing wave) that got excited by the previous system, now doesn't occur.