GRAMMA!

I recently bought (for about$49) the GRAMMA isolation platform by Auralex from Sweetwater.com. This thing definitely cures the slight boominess I was experiencing. It happens to be just the right size, too for the LFM1. Recommended....

I ordered one of these today so when I get it I will post my opinion also. I just got one for the LFM and the dimensions seem ok.

Guys,
Please let me know how the Auralex works out. Both my LFM-1's are on a wooden floor and even with the metal discs they STILL move...not that loud!!!! Help.

I got the Gramma today and placed it under my Velodyne(LFM arrives tomorrow). What a difference! It actually makes me appreciate the Velodyne. I put in Attack of the Clones -Scene 3- and the explosion of Amidala's ship was tight. Before it sounded sloppy and muddled. The Gramma is an excellent purchase. I can only imagine how it will sound with the LFM. Highly recommended.

Hello everyone

Thank, JMS, for enlightening us to this product. How did you come across it?

I purchased a 950/7100 combo in December and I like it alot. It is by far the nicest audio electronics I've ever owned. The satelite/sub system is from Aperion, which seems to be pretty good quality, and I'm happy with that as well.

I have gone through all of the standard operating procedures for calibrating the speakers/sub, moving the sub to a better location in the room, and adjusting the phase and crossover settings on the sub itself. It all sounds pretty good. However, the lower bass frequencies are still a little heavy relative to the upper bass frequencies. It's not too bad, but it needs another tweek of some kind to get the right balance and tighten it up a little more.

I wondered if this GRAMMA isolation platform would be worth a look. Does it function well with any kind of sub, or is it more appropriate for downward-firing subs? The Aperion sub has the speaker cone facing forward into the room, a port in the back, and it is raised off our wood floor with floor spikes and little brass discs.

I would appreciate hearing anyone's experience and opinions on this, if you'd be so kind.

Thanks.

I just hooked up the LFM tonight and it fits perfectly with the Gramma. Bass is killer. I just wish I could really turn it up but ,alas....darn townhouse neighbors! Oh well , it will grow with me when I move that's for sure. But I digress...
The Velodyne CHT8 had the speaker in the front and this one is downfiring but the Gramma seems to work well with both. I have tile flooring so I do not know how it would work with carpet but it made a big difference in my house. It seems to keep the really low stuff from getting sloppy and tightens it up nicely(forgive my highly technical jargon) .
Like I said before, I highly recommend it.

Elevatedlizard:

The location should be given the first look. If you are all out of location options, I’d say try some bass traps before trying anything else. Aurlex has them and so does this place http://www.realtraps.com/

Thanks, guys, for your input and response to my inquiry. Spiker, I especially appreciate the link to Realtraps you included with your post. The information at their site helped clarify for me acoustical properties that I only vaguely perceived. What they say makes sense, and since I know nothing, I will have to take it on faith that this appraoch will yield noticable results. The most challenging aspect of this project is to convince my wife that an installation of acoustic panels will visually improve our living room.

For a quick, but noticeable, change in subwoofer response and isolation, the GRAMMA (also known as the "Subdude) does the trick. I've owned one for over a year now and I'm still impressed by how it helps isolate the sub from my floor. Proper acoustical treatment is a good path to take, I also especially like the realtraps product, but don't mistake taming reflections for acoustical isolation. 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.

For $60, I've found the GRAMMA to be one of the best tweaks yet for my system. It does exactly what it says it's going to do.

You can cover it with patterned fabric of some sort and staple to the frame or pin it at the back. You can even have your wife pick one out. I’ll bet that will make the spouse approval process smoother.

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?

.

http://www.msnusers.com/stereoandtruckphotos/shoebox.msnw?action=ShowPhoto&PhotoID=11

works 4 me

Hey ! I did not see those on the Sweetwater site. Thanks. They are on the way.

I recieved the Auralex Mopads yesterday and set them under my center, back and surrounds. Nice. the bass is more focused from each speaker and the sound just seems a little more precise. Not in a huge way (they are just foam rubber pads after all) but enough to notice and make them worth while. Thanks for the suggestion.

Ya know, Bestbang brought up an interesting paradox. On one hand, our GRAMMAs decouple our speakers from the floor. OTOH, spikes attempt to couple 'em to the floor, even through carpeting. Seems to me decoupling would take the quality/makeup of the floor out of the equation. Wouldn't a speaker floating in midair have the least physical interaction? All I know is, the GRAMMA tightened up the bass coming out of my lfm. Seems like a cheap fix to me!

Jay

I suppose it's up to the individual user to determine if potential sympathetic vibrations from flooring are advantageous in a given environment or not.

It is amazing to me that some people are marketing spikes as a means to isolate vibration. Spikes change the way a loudspeaker's cabinet is physically coupled to a stand or to the floor. This may cause the cabinet to vibrate less by giving the kinetic energy a partial "drain" thereby changing the way a loudspeaker sounds, but the energy that is drained away from the cabinet has to go somewhere. From a physics point of view, spikes are an effective means to transfer some of the kinetic energy from one object to another.

I have a one inch thick rubber mat. Do you guys think this would perform just as well as a gramma? I have'nt received my sub yet but just curious.
Thanks, Daman

All this depends on if you live on a drum or a rock... Take a piece of 2x4 about a foot long and place it on your floor and hit it with a 5 lb hammer.. How does it sound?

Good=Spikes
Bad=Isolate

I think thats the ticket

Better yet.

If you have carpet, take a sheet of plywood and place it under your couch, with two feet sticking out the left or right side. Put the LFM1 on top of that..

Instant Butt Shaker..

Well, they are. The question is why anyone would want to.

It does radiate vibration, but only at the frequencies that *it* wants to, not what's in the music. In other words, it resonates like a drum.

It probably does sound better there, but don't put that on the differences in the floors. Most likely the culprit is the room itself, and just as importantly where the sub is placed in the room. A difference of 6 inches can be heard quite clearly.