SVS Subwoofer Isolation feet. Will I lose bass?

I go back to where a guy on YT did an experiment with the SVS rubber Isolation feet on his sub in sealed mode on a concrete slab and the output was significantly less when measured with a mic.

Right. Makes perfect sense.

Anything squishy, be it rubber or spring, ball or whatever, the energy from the driver will cause it to compress. Once compressed it is going to expand. This compression and subsequent expansion occurs, to some degree, in every material. Every material does this at its own particular rates, and these rates vary according to frequency and amplitude for each material.

So what happens when you put squishy stuff like springs or rubber rings under something like a speaker? Well, what happens depends on the frequency and amplitude we’re talking about. Its not like its all the same across the board.

Something like a metal spring, no damping, this is going to bounce up and down at whatever resonant frequency. What this means is sometimes at one frequency the spring will completely suck the energy out of the system, while at other times it can resonate and increase output. This is just basic physics. Same thing happens with the rubber feet, the difference being the harmonic frequency and degree of damping, if any. It may well be the SVS is fairly highly damped. In that case it would not resonate, not to anywhere near the same degree, and so there would be no frequency where it would add to output. There would only be frequencies where it subtracts.

So now you have one totally sensible and science based way of explaining the measured output observation.

One. There’s another. These things look to be pretty thick. Boundary wall reinforcement is greater closer to the floor or wall. Raised up off the floor, even a little, less reinforcement, less bass output.

So now you have two perfectly sensible science based explanations of the observed measurements.

How odd Audiogon’s reigning theoretical physicist wasn’t able to think of either one. Huh. And his system is... oh, that’s right, he doesn’t have one.

None taken. To offend calls for standing you don’t have.

I would post a link to his website, but every time I do he has it removed. He likes to mislead and insult, but never inform, and at the same time loves to sell the unsuspecting who stumble onto his flying saucer website. So you will have to search him out and find machina dynamica on your own. Then ask yourself how much time and effort you want to put into pursuing the advice of such a one.

geoffkait, I understand that. But if you have a sealed sub on a slab, wouldn’t the "wobblyness" be counteractive to the woofer?

Yes. Exactly.

One thing you need to understand, you are taking advice from a self-proclaimed theoretical physicist, who designs interstellar rocket propulsion thrusters in his spare time and has a website devoted to flying saucers. His most impressive accomplishment is consistency: 21k posts, and not a one of them worth reading. Irrelevance on such a scale is remarkable even among audiophiles.

DYODD.

Unless you've invented anti-gravity there's no such thing as isolation. What we have instead is vibration control. And you're right, shakey rubbery feet will damp vibration, sucking up energy and causing you to lose bass.  

Not very much however. Most all of these things work great because they work at midrange to treble frequencies where the ear is extremely sensitive even to micro-amplitude effects. All you have to do is squish one to see the most you can compress it is a very small amount. Its measured in hundredths of an inch. Then you look at the amplitude swing of a woofer, its measured in inches. You don't have to be a rocket surgeon to know they're not gonna have a whole lot of effect on a sub, one way or anther.

Audiophiles however are not even up to the level of rocket surgery. So expect a lot of different answers.