SVS Subwoofer Isolation feet. Will I lose bass?

I thought that the test that showed the most deviation was when he used the packing foam as the mounting device.

It is my understanding that a ported cabinet is a tuned cabinet where the designer is using the cabinet vibrations and internal air pressure to help increase output and enable the sub to cycle lower. In the REW analysis, there appeared to be very little difference in output and low end extension with the three mounting methods (iso feet, packing foam, batteries) when the sub was in extended and standard modes. When the sub was in sealed mode there was very little difference between the iso feet and the batteries but a significant difference with the packing foam.

So my conclusion, though maybe incorrect is that the iso feet aren't doing a lot, at least on a concrete slab, and that the port plugs and the packing foam are changing the tuning of the cabinet in a way that reduces output and low end extension.

I believe that he did not run the test with the stock feet.

Test 1 - Iso Feet
Test 2- Packing foam
Test 3 - Batteries (ridged)

Some people posting on this thread are not nearly as amusing as they think they are.
 This forum would be a far better place without them

to the OP, as with anything your mileage may vary, so I'd recommend finding a low cost way to test this if you are interested in how sub isolation might affect your sound.  Either find a place to buy with a return policy or buy them used at a price you can then resell at.  

I'm using isoacoustics feet on my Martin Logan towers to good effect (and well worth the $) but when I tried using similar isoacoustic pucks under my ML sealed subs, I found they made the subs sound horrible.  I actually thought I had a woofer that had gone bad as I was getting audible distortion from them.  I removed the pucks and the sound returned to normal.  

I don't have a detailed explanation as to what caused these particular subs to react so negatively to this particular product in my room, but suffice to say that these types of products can impact the sound and sometimes that change will be positive and sometimes it will be negative.  I think you just have to try and let your ears tell you whether the change was better or not for you.  

@shiner01  Thanks for posting.. Great information.

But Geoff....If a second "Spring System", applied to the vertical plane isn't identical to the first. And in fact is designed to augment the first in a resistive fashion. (By design, tuned for a different cyclic wave range, with also a transduction medium utilized between layers, "Each a discrete (compartment), in a multi-layered architecture". So that instead of the way that a spring usually and inherently utilizes as it's means of kinetic dispersion, it cannot interfere with the other system involved). Would that not be beneficial? It would only be detrimental if the range of each spring "System", indeed "Crossed" by a fair amount. (>.007%). Which could also cause odd harmonic resonance. This will also increase the efficiency of the spring in the 8.32Hz-50KHz range. "Funny how it seems to begin at the "Schumann", resonance"!
 This is only, "Of course" in a multi-layered, Constrained layer system.
And um...Using a certain alloy of brass which has been in fact, (Cast) in the springs construction seems to help "ALLOT". I also still have a few of the, "links" to a few of the studies done on the specifics of this. In case anyone would like to peruse them.
 Hee hee, But I'll warn you now, they are quite the exhaustive read!

One more thing I have noticed in experiments with "Constrained layer damping" systems.
And this is a bit weird! But interesting all the same.
 Everyone knows that three points make a perfect plane. And you must have at least three to make any "plane".
 Also that anytime more than three are used? You may ONLY make an "Imperfect Plane". And of course we all know that, No- "Perfect Plane", can exist even in theory, with more than three points.
 Basic physics, and at it's most easily defined, understood and excepted level right?
Where this got interesting was in my plotting though "Cymatic" figures for vibration analysis. While, "Transitioning known quantities of specific vibration through differing transduction devices/systems/materials as accurately as possible was the goal". This for a "Baseline".
{{Why? Because,
 If I do not make it? I will never be able to have the fun of figuring out how to break it.}} Also It should improve the sound of any system tuned for where applied.
 Anyway, The goal being- So that on each side of the equation?
 The, "Cymatic", physical representation plotted with the same equipment should at least, "Resemble" that of the other side. Just a difference in amplitude if done correctly. Fairly simple right?
But while using these springs. "Yeah, I am going to blame this all on Geoff! I wasn't much on springs until that kernel was placed there by Geoff. 
I had an idea coalesce from something I had recently read in another's notes. "He has long since passed and I do not think would mind".

"As we look at the six original Solfeggio frequencies, using the Pythagorean method, we find the base or root vibrational numbers are 3, 6, & 9. (AND)-. Nikola Tesla tells us, and I quote: "If you only knew the magnificence of the 3, 6 and 9, then you would have a key to the universe."

And so, simply because I could. I figured "WTH", and why not.
 Using only sets of three, for each plane.  As the only points on each level of three layers.  And this in a symmetrically balanced, vertical structure, that of a three layer system?
 After all of that? 
It just wouldn't work!
Well, not until I applied a voltage..... Then it became a "Polarized system".