Thanks guys. The sub is already isolated to the extent that it is raised up on floor spikes, so its points of contact are minimal. Would an additional isolation pad serve to reduce the compounded bass in some parts of the room, and counter the effects of cancellation in other parts? I won't know until I try it, I guess.

Within the limitations of having a home theatre in a multi-purpose room, I've got it tuned-up pretty good. Is it perfect? Of course not. Is it worth worrying about the last little bit? Perhaps only if you're descending into that maddening hell of audio perfectionism that is the bane of every audio nut, like the one I fear I'm becoming (I'm passing out the grains of salt right now...).

Aside from the furniture, our living room has little else that would help modify it acoustically. The mini blinds are probably as reflective as the plaster walls. The little bit of reading I've done so far indicates that acoustic treatments help minimize the impact of the acoustical properties of the room itself, so that your're hearing your speakers more, and the room, less.

Now, if I can incorporate this into a painting/decorating project...

To boldly stumble where others would pause thoughtfully,

Best Regards.

Thoughts on "solid" spikes and GRAMMA-like products:

On a carpeted surface, which of these three situations would transfer the most kinetic energy to the sub-flooring? Which situation would transfer the least?

1: A very stiff table is placed on the carpet upside down so that the weight of the table is spread out across the fibers leaving them uncrushed and with some flexibility left in the carpet and carpet pad underneath. A bowling ball is dropped from one meter above the tabletop such that it lands on the exposed side of the tabletop near one end.

2: The same table is turned right side up and left to sit for a month. The pointed legs crush the relatively small amount of carpet and padding under them leaving no flexible material between the end of the leg and the sub-flooring. The bowling ball is dropped from one meter above the tabletop and lands on the very stiff tabletop near one end.

3: The same table, either right side up or up side down, has placed under each corner the following - a one foot square of ¼” plywood; on top of that, a good bath towel folded to 2” thick; next 2” thick sponges side-by-side to cover the folded towel; and then another layer of foot square of ¼” plywood. Again the bowling ball is dropped as before.

Got your answers yet?

Situation one is like a speaker without spikes and without extra vibration absorption.

Situation two is like a speaker with solid spikes. The cabinet vibrates less because some energy is transferred to the sub-flooring. If your sub-flooring is thick cement, you’ve probably done a good thing, little sound emission from the floor. If your sub-flooring is plywood or hardwood strips on wooden joists, your subwoofer has turned your sub-flooring into something like the surface of an acoustic guitar - if your spikes are solid end-to-end, the spikes are like a guitar’s bridge and the floor is a sounding board, plenty of sound emission from the floor.

Situation three is like a loudspeaker sitting on a multi-layer vibration absorber-dampener. The cabinet vibrates less because some if the kinetic energy goes into the layers. The floor vibrates less because the layers keep the kinetic energy isolated from the floor.

What’s your preference?

I have to add that isolating my sub (DefTech SuperCubeI) made a significant difference in the overall sound. Tighter cleaner much much less boomy-ness. This is especially true for music.
I use Soundcare Superspikes threaded to replace the supplied feet http://www.taylorsales.com/SuperSpikes.htm

I actually use these same (but non-threaded) under my L/C/R speakers which areon built-in shelving and there again it is a noticeable tweak.

I recommend this fairly simple step whatever your chosen product. It just cleans up the sound so much.

I have to add this:

My favorite audio sales guy, who has at least 30 years in the business, told me about why there are spikes on speakers.....


Stability on Shag Carpet

But, Grasshopper, did he reveal to you why there is shag carpeting?

To complement the orange flowered wallpaper and avacado kitchen appliances.

"The GRAMMA actually isolates my sub from my floor, noticeable in reduced vibrations in neighboring rooms. It DOESN'T reduce actual bass level except to eliminate any items in the room the may be vibrating along with the sub."

see next post

I thought spikes are used to transfer vibration to the floor?

I have a cement slab floor in the room my sub is in, and it sounds very dead. I've read in other places that rasied wood floors are bettter for subwoofer performance because the floor helps to radiate the sound. My LFM-1 sounds a lot better at my dad's house w/ raised wood floors vs. my slab floor. He has essestially the same system driving it as I do. So, this whole concept of isolating the sub from the floor seems counter to the whole wood floor vs. slab floor issue.

Maybe in a very live room with lots of reflective surfaces the isolator is desireable?

I gotta look into these...
Bill

I woke up this morning and thought to myself ' Hmmmmm if the Gramma makes my sub sound that much better...I wonder how my floorstandings (Polk Audio Lsi15) would sound if I placed this baby under it?'

Well...Lo and Behold ! Darn if it did not dramatically improve those too. Two more are on the way. Now I just need to find something to put under my center speaker. Maybe a smaller version? Any ideas?