What should be under my speakers?

I have Sonus Faber Grand Piano Home speakers in a 20' x 17' room with wood floors. The speakers have spike feet, and each one is sitting on a 1 inch thick, 12" x 12" slab of granite. Each piece of granite has a square piece of carpeting under it, as a further buffer. I know I probably could figure this out with a lot of experimentation, but what impact is the carpet likely having on sound quality? Would it be better (Subjective, I know) to have the granite slabs sitting directly on the wood floors? How would the sound change if I ditched BOTH the carpet and the granite? I would like to maximize bass impact, because these speakers are a bit thin in that regard. Thanks.
If it were me I would write Steve Herbelin at Herbie's Audio Lab and ask what he suggests. I have his Grounding Bases under my Meadowlarks' spikes ( to good effect ) but he has other products for your purpose as well.

I would try something like the Star Sound threaded feet under the speakers. I sell these so I know they are good but there are others. Are you trying to couple the speakers to the floor or decouple the speakers from the floor? If you are trying to ground the speakers so cabinet vibrations would be quickly dissipated I would not use anything under the spikes but here , as always, experiment is best.
This has a simple and wonderful solution. Star Sound Sistrum stands will improve your sound by a large degree. Look at the Star Sound website for the best Sistrum stand.

They will just amaze you as the work great!
Sistrum platforms are more effective than Audiopoints threaded footers at altering (some would say improving) a speaker's presentation , IMO.

Neither will provide a jaw dropping revelation, but you may find one or the other a worthwhile improvement.

Try to buy used so you can try them and resell them if necessary.
I placed them (Sistrum) under my Dali speakers and the sound become far more transparent, focused and composed. The bass was far better controlled and articulate. Loved them!

Your experience may vary.
Just wanted to give more info on my experience with the Sistrum SP-004 and SP-1 stands.

My Dali Grand speakers were 100lb floor standers with 2 bottom mounted 8" woofers per speaker. Bass was at times heavy and just a tad slow. Very warm and slightly midrange forward tonal character.

The SP004 units delivered a very noticable improvement. In fact, in the order of a very expensive wire or component upgrade.

As TVAD says they are expensive and can be found used if you are patient. They sell used for 1/2 the new price. I purchased Adona floor discs to protect the wood flooring. They cost much less then the Star Sound floor discs.

If you have any components on the floor these do the same magic under those components.

I suppose the improvement will depend on the speaker and room.
soundcare superspikes. google them. i use them for my b&w's on my wood floors that are on concrete slab. they are exceptional.
I have owned all of the above solutions… I have had each on wood and carpet… Starting with spikes on Granite or stone block(concrete)… This is probably one of the worst solutions I have heard actually.. And Even have used the same stone block on TOP of the speaker to see what would happen, as it was better than under the speaker, but still took away some integration and warmth of the speaker.

I have also tried MDF blocks like a slab 2" thick on top of carpet… Again not the best results separated the integration and overall impact of bass…

Then going into Sistrum Stands as mentioned on wood, worked well, but Very difficult to do these without damaging your speaker bottom or wood floor, although it can be done.

Then I went to the straight sistrum spikes threaded right into the speaker vs. the stands and with my speakers ended up being slightly better as it brought the sound floor of the size and scope to a more anchored sound, filled the room better. But the stands probably brought out a more Airy presentation.

Spikes or Sistrum stands were far Superior ON CARPET… Over wood.

So in the end with several pairs of speakers later now, I have found the best solution for you on a wood floor is Dump the granite slabs definitely, use the Spikes threaded right to the speaker base plate as they are, buy a couple Really thick carpet squares to put one under each speaker with spikes right into the carpet, hopefully they don't go right thru and stick into your wood floor, first because they can obviously leave a hole in the wood, and also because you will not be able to slide the carpet around to move your speaker back into correct positions or adjust toe in etc…and of course can put some nice gouges in the wood possibly.

You can use the little spike "dimes" under them if you wish to make sure the spikes will not go thru a carpet to your floor, or if you rather skips the carpet square and go directly on your wood floor with the spike protectors.. But I will tell you this, a Good 9 foot or 12 foot wide by like 6 or 8 foot heavy throw rug in front of your speakers (not under but you can use this under) will definitely help your sound as it will absorb your first point reflections out in front of your drivers beaming off the floor into the room, and just sounds better when you have a carpet between your seating area and speakers anyway.

The issue with the "Best" solution is your room frequency responses and other issues will come into play with the interaction of your speaker in the environment as a whole, not just how its coupled or de-coupled to the floor although this is a big part of it. So not sure what kinda room acoustics your getting now if that’s also going to need far more attention to ever get you the results you desire.. Don't believe the hype about a 400 dollar or 4 dollar spike set doing a whole lot if you have other issues to be addressed.. Again I can say dump the stone blocks under the speakers, and for sure make sure you have a good carpet out in front of the speakers to truly effect the bass response and soundstage. Just start with that and drop the speakers with spikes right on the floor as step #1…. Placement of the speaker will become more critical in the room than any of this.      
Nothing. Spike the speakers to the floor. Forget about the 'dimes', the object is to couple the speakers to the floor. Otherwise, you are trying to couple and then de-couple. One will work, the other doesn't.
Buconero is right.........and wrong!
Spike the speakers directly to the wooden floorboards.
The objective is NOT to 'couple' the speakers to the floor, but to DE-COUPLE them whilst at the same time creating a stable, unmoving, balanced speaker box.
The tiny contact area of the spikes will not allow medium to low-frequency sound transfer from either the speakers to the floorboards and vice-versa whilst 3 spikes will prevent any rocking.
Sistrum stillpoints under my Thiel 3.6 into an oriental rug over a cement floor works very well for not a lot of money.
I recently experimented with spikes and other methods of isolating floorstanders. My goal was a little different, I was trying to remove bass vibration that I could feel at my sitting position. Spikes made no difference, neither did a buildup of carpet at the site (although one commenter suggested a thicker carpet over the entire floor - which I believe would have worked.) Anyway, I ended up sandwiching 1/4 inch sorbothane (the stuff used for running shoes) between thin sheets of plywood - essentially a single ply. Creating two layers. This caused a noticable reduction in the vibration. Never one to trust my senses when it comes to measurement (spent too many years as an engineer to know the flaw in that method of 'measurement') I created a measuring device out of a thin glass of water, placed on the floor. The deflection in the water movement up the side of the glass was less with the construction in place than without or with the spikes. This was on a wood floor in an old house. I cannot say that I noticed a difference in sound, but that was not my goal, and I noticed no difference in sound spiked, on the constructed sorbothane - plywood plates, or directly to the thinly carpeted floor. This obviously was at high spl levels.
I second the Sistrums - amazing. I lent a pair of 004 Sistrum stands to an audiophile friend and he ordered a pair the same day after hearing them on his speakers. They transformed my old pair of Audio Physic Virgo II speakers. The effect is not subtle - it really is transformative. I now use the Sistrum monitor stands filled with microbearing for my MBL 121 monitors.
Yes, the Sistrums really work and they proved it over and over under my gear. I can't say the same for all the other things I have tried.

I took a 004 to a friends house and tried it under his CD player, pulled it out and the difference was amazing. The CD player sounded so much better with the Sistrum underneath it.

As I said above they did a nice job under my Dali speakers also.
I installed Sistrum SP-101 stands under my Silverline Sonata III speakers, and my wife, who has demonstrated her keen hearing over and over again, stated she did not hear a difference.

I still have them installed, but in my system the effects of the Sistrum stands are subtle at best.

Keep in mind, I have never used the term "jaw dropping" or "eye opening" to describe any component, element or tweak in my system, so what I describe as subtle someone else might describe as transformational...

It's all individual perception.
Time warp..Just a few years back the mere written word Audiopoint, Sistrum, coupled, resonance transfer, those words those terms were beaten up on these pages. So now with a little temperance from all involved, myself included those once riddled words are a now apparently a respectable thing. Cool! Tom
I have tried a number of solutions, stone slabs with Nordost Pulsar points, herbies big fat dots, spikes etc. The best I have found is Symposium svelt shelves, Rollerblock Juniors. Better base definition in particular, but not earth shattering
I use Outriggers and find them to be excellent. They are also a lot less expensive than most solutions. I can't see any advantage that Sistrum would have.



With Outriggers, do the speaker rest directly on the flat metal plate?

With Sistrum platforms, speakers sit on three brass cones which are fixed onto the brass plate.

I can't say how one sounds versus the other, but from what I can see from the Outrigger photos, they do not appear to share the same structure/design.
Do you have any options as to the positioning of the speakers, with regard to how they 'load' into the room, i.e. short wall, long wall.
By placing the speakers so that they a firing in the same direction as the floor studs, (assuming it's not on a slab), you will help the bass to develop; whereas firing across the studs, breaks up the bass.
Years ago, I experimented with speakers in this regard, in my Audio store, and asked people to listen to the speakers positioned in opposing directions, cross hatch, and then, firing with the studs. With normal bass output speakers, it was unanimous--that is everyone preferred firing along the floor studs. Interstingly, no one knew exactly what I was experimenting with--so it was like a blindfold test in some ways.

The outriggers are really good. AND, as theaudiotweek points out, the Sistrum work very well. I was not convinced until I tried them in my own system.

I can tell you without an audible doubt with my ears and two other pairs in audience that tighter coupling is more benefical than that provided by leveling. Unless you use additional added shim or shims of the same material you will loose coupling integrity with any leveling system I have encountered. The benefits of this maximum contact are better bass weight and midbass speed as well as greater image resolution. The last statement of vision would make you think my speaker was precisely level when in fact it was not, it was however precisely coupled to all surfaces. Tom