[AB]

I'd like to hear any positive or negative stories regarding decoupling speakers with slabs of granite or what- have-you.

I'm still trying to squash the remaining bass peaks from my seemingly ridiculous room.

I figure the extra mass plus an added few inches off the deck might help.

TIA all.

[timind]

Hopefully I'll be able to answer the question soon. I ordered two pieces of granite from an ebay seller and am still waiting for delivery. My intention is to put the granite on three cones and decouple the speakers from the granite.  Should be interesting.

[AB]

Keep me posted, thanks.

My 210+ pound speakers are sitting on a suspended floor. The floor just about bounces with energy at a few frequencies so I've moved the speakers BACK towards the front wall because there is a nice fat lam beam supporting the floor there. That's helped control the bass but further out the speakers open up but the BOOM is overwhelming when they're out there off the beam and relatively unsupported.

[Philistine]

I had a spkr knocked over by one of my kids, so when I upgraded to a pair of B&W 803's I bought a pair of Sound Anchor stands.  A beautiful pair of cherry wood spkrs and pieces of crappy iron welded (I use the term loosely - reminded me of welding on 1970's Jap motor cycles) together by untrained cheap labor = beauty and the beast.  The Sound Anchors went back pronto.
I finished up importing a pair of beautiful granite bases from HNE Systems in the UK, the profile of the stands followed the profile of the 803's - they looked great.  So I achieved my objective of stabilizing the 803's but also discovered that they really tightened up the bottom end and gave faster bass response.  So yes granite can work.
When I bought a pair of Salk HT3's I contacted HNE and they wanted 3 months to get them shipped out - I finished up going to my local granite dealer and paid about $80, he knackered up a few drill bits so he's not interested in repeat business.  I promised Jim Salk that I'd post this on his forum one day, as he's had customers with vibration/resonance issues.  With the HT3's I haven't really done an A/B with the mdf plinth vs granite, but based on my experience with the 803's it's a no brainer for me.  From an aesthetic perspective granite looks great with wood, and you also get a more stable structure in addition to any decoupling benefits.      

[satfrat]

AFAIC, marble, granite, whatever stone would be better used on top of loudspeakers for mass loading instead of being used as a base. I like cones, especially for wood cellar floors and specifically Sistrum Platforms from Star Sound Technologies. I've tried marble on both ends and this is what worked best for me in my system and on my weak-a$$ wood cellar floor.

Cheers,
Robin

[max190]

I know these http://truesoundcontrol.com/products/SUBDHD.html are designed for subwoofers, but I wonder what effect they would have under spkrs?

Anybody try the SubDude?

[Wayne1]

I also have my speakers on a suspended floor. I tried direct coupling with Sound Anchors stands and it just made the boom worse.

What I found to work in my case is to try to ISOLATE the speaker from the highly resonant, suspended floor.

Herbie's Audio Lab offers quite a few products for this.



The Superior Carpet Spike works wonders with carpeted floors. It adds a layer of Herbie's dBNeutralizer material between the speaker and the floor. This will prevent the energy from your speaker cabinet from being transferred to your lively, bouncy floor.

If you have hard wood floors, Herbie's Big Fat Dots will do the same thing.



I would not use granite. Granite is a HIGHLY resonant material that will will transfer acoustic energy very easily.

I remember before a show, I visited Chris Brady of Teres Audio. He had planned to use a granite slab for isolation. The many hundred pound block of stone arrived. Chris set it up, then he rapped it with his knuckle. It rang high and sweet and kept ringing for some time.

[richidoo]

If you have a crawlspace or basement below, the floor can be supported under the speakers with a beam/post installed from below. Doesn't have to be anything fancy, since it is not load bearing. mfsoa did this and recommended it to me. Herbies sounds like a good idea too.
Rich

[rlmacklin]

To: AudioLab@att.net
Sent: Tuesday, August 26, 2008 10:29 AM
Subject: 8/26 order of "Von Schweikert Special"

Steve,
 
I currently have Polk Audio SDA-SRS-2  for front left/right speakers.
These weigh approximately 135 lbs. each per Polk product literature
They are direct on carpet at present.
 
I ordered the "Von Schweikert Special" as it had the complement of
4 Big Fat Black Dots plus a Square Fat Black Dot per speaker -
which seemed to be a good configuration to me - at a somewhat reduced price for the package.
 
What sort of base would you suggest to go under the Herbie's Dots -
granite, wood, _______ ???  I would guess something other than direct on the carpet as now...
 
Thanks,
rlmacklin
 
P.S. Your Ultrasonic Dampers really helped the Modwright SWL 9.0 Signature tubed linestage
(one 1957 Philips Miniwatt metal base GZ34/5AR4 rectifier and two Bendix gold pin 6900 signal tubes)
 

Reply frojm Steve Herbelin ("Herbie"):

I would recommend a 3/4" or 1"-thick granite slab for each speaker. Granite slabs can be made to the same size/shape as the loudspeaker footprint by a gravestone maker or kitchen remodeller. Granite comes in lots of different colors and the finished, polished result is very attractive. You'll have sufficient weight/mass that you won't have to spike the bases to get ideal results with Big Fat Dots providing excellent isolation/decoupling. A matching granite slab on top of each speaker cabinet should add additional benefit (decoupled from the speaker cabinet with Herbie's "Thin" Fat Dots).
 
Regards,
 
Steve
Herbie's Audio Lab
 
***********************************************************

I stopped by the fabrication shop of a kitchen countertop company after I had inquired re pricing.

The shop foreman showed me remnant pieces which would be free and I picked out two 1" granite slab bases of matching color which matched size of the speakers with some leeway.  These were already with slightly rounded corners (kitchen sink cutouts ?). 
I placed the granite slabs in position and then the Polk SDA-SRS-2s and added the Herbies Big Fat Dots under the speakers at the 4 corners and square dot in middle, for decoupling.

I would call it SUCCESS in that low frequencies "snapped into focus"
and the mids and highs were livelier but without glare.

Highly recommended.

[satfrat]

If you have hard wood floors, Herbie's Big Fat Dots will do the same thing.



I would not use granite. Granite is a HIGHLY resonant material that will will transfer acoustic energy very easily.

I remember before a show, I visited Chris Brady of Teres Audio. He had planned to use a granite slab for isolation. The many hundred pound block of stone arrived. Chris set it up, then he rapped it with his knuckle. It rang high and sweet and kept ringing for some time.

I use 5 Herbie's Big Fat Black Dots under my 2" marble platform that mass loads my ACI Force XL subwoofer and 4 large Audiopoints underneath. 


Cheers,
Robin

[AndrewA]

I epoxyied together three 12" x 12" black granite tiles per side from Lowe's, and then added Dayton black gloss solid brass 2" carpet spikes with adjustable tips.  Four small rounds of bluetack near the corners go between the speaker base and the plinth.  I notice a mild improvement.  Bass is tighter, and the extra weight and the longer spikes actually get right through the carpet and pad all the way to the subfloor.

I conjecture that three fairly thin layers glued together may actually be better than one single piece, as you will get some of that "constrained layer" effect.  Only afterwards did it occur to me that I could have gone other routes--trying perhaps a marble tile sandwiched between the 2 granite or vice versa for a zebra effect, and of course different materials with different resonant qualities in the layers.  Unfortunately, no way of knowing until the epoxy has set--and by that time one could have done the bathroom floor...!

[AB]

I have been considering the Herbies products. With his guarantee I can't see any reason not to try them.

I was also thinking of building a constrained layer platform using two pieces of thinner granite with a sorbothane sheet sandwiched between them. McMaster-Carr sells 1/4" think 12"x12" sheets for $30.
But that'd take some effort and I'm feeling a bit lazy at the moment.

I also wonder how much effect there would be from simply raising the speaker an inch or so above the floor.

But just in case I ordered a couple more bass traps from Real Traps A few more of those can't hurt.

[sbrtoy]

If you have a way to access the floor (crawlspace) I would highly recommend fixing it first.  This is a project I will be undertaking very soon in my rooms as they are in the basement and have suspended metal beams under them making huge amplification for bass nodes.  

Try www.silentsource.com for ideas and products, and no I am not affiliated in any way with them  

[AB]

Under the "Audio" room is the "Automobile/Motorcycle/Bicycle" Storage environment.

The floor joists are already doubled up  - the room is an addition built onto an already existing garage - and there are those three big lam beams plus their supports in place too. The ceiling was insulated and dry walled to prevent the Non Climate Controlled Vehicle Storage environment from impacting the Climate Controlled human comfort area above.

I don't know what more could be done down there.

I just ordered some decoupling carpet spikes from Herbies.

So next week there'll be a few more traps and some new carpet spikes to play with.

[sbrtoy]

I am going to add green glue and an extra layer of floorboard under my existing carpet, this is supposed to be a great help in reducing bass resonance in particular and is an easy retrofit.  From there I may also attack the underside of the floor from the crawlspace but you won't have this luxury.  I have also heard good things about laying a vinyl blocker under your carpet pad.

[viggen]

I use BDR cones pointing down between my speakers and my surface plate granite.  The theory is the BDR cones direct vibration into the granite, and the granite disperses the vibration. 

[djbnh]

I use granite to great success under my speakers (speakers used to rest right atop a thinnish carpet). The slabs, each about 40 lbs, came free from a local shop's discard pile, so the price was right. Highly recommended tweak. I note I've also wanted to try the speakers on the granite, sandwiching either cones or Vibrapods between the two, but haven't gotten around to it.

Best of luck with your experimenting to find out what works best for you in your room with your gear to your ears.

[Zardoz]

Interesting read.  Since I work in the stone sales industry I wanted to toss out what may be helpful advice: a popular and similar stone slab product to granite is quartz, otherwise known by the many brand names under which it is sold - Silestone, Zodiaq, Caesarstone, etc.  This is a man-made "engineered" stone product that is comprised of 93% actual quartz stone, mixed with colorings, resin, etc.  My point here is that as opposed to granite, which usually has a minimum order no matter where you get it, quartz usually has no minimum order!  That means you can get a 12" piece in any color, or do a different color for each speaker, etc.  Quartz is very similar in pricing to granite, so while paying $50+ per square foot may sound worse than free stone scrap, you are getting exactly what you want.

[satfrat]

The Vermont marble I use is called Champlain Black marble cuz it was harvested from the shores of Lake Champlain and is a black marble full of crustaceans & shells and speckled with white. When polished the shells & crustaceans really pop. The fact that the quarries are about 7 miles away make it sorta special



Cheers,
Robin