Spikes versus Rubber on wood floor?

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.

Nsgarch, you could be right, but I doubt it since I fixed the problem with decoupling like many others have here.

I might not have a minor in acoustics from MIT and I also don't have an engineering degree either, but I can tell when my car is spark knocking and how to fix it from the experience of others. But I certainly don't need to tear the engine down!

The fact is, I did cure the problem in my room without having to tear my floor up or re-engineer the joists as you suggested. But I guess if you can't find a simple solution like decoupling there's always the big hammer approach, huh? And btw, being a licensed contractor doesn't mean you are an experienced builder. You know there are licensed contractors and licensed contractors!

And I anticipated your, "There are architects and architects; sorry you didn't find a better one.", after your, "apparently you have a very under-engineered floor."

From your attitude, it appears that you are the only competent architect around. Too bad everyone just doesn't hire you.

Fiddler, as in all professions, there are some incompetants, many bright ones, but few brilliant ones. The fact that your problem was solved with a speaker change and not with a construction project is what led me to my conclusion ;~))