Floorstanders on wood floor, help

Here's the setup:
- suspended wood floor, joists accessible from below
- jute carpet pad, very dense
- carpet, very dense/tight pile
- B&W N803's

We want to eliminate bass bloom while preserving attacks and PRAT. Here's what we've tried so far...

Nothing, flat on the carpet...
soft attacks/PRAT plus lots of bass bloom; worst of both worlds

Speakers on sorbothane footers on wood boards...
eliminated bass bloom but killed attacks/PRAT; deadly dullness

Spikes long enough to pierce carpet/pad and reach the floor...
great attacks/PRAT but enormous bass bloom; coupling to a 13 x 17 x 8 bass drum is not the right idea!

Spikes just shorter than the carpet/pad thickness, so not quite touching the wood floor...
great attacks/PRAT but still annoying bass bloom on some recordings; best we've tried so far, but could be better

Any ideas to preserve attacks and PRAT while controlling bass bloom? TIA.
My final solution was to place a 24"x24"x1" granite slab on the carpet and Aurios MIB between the granite and speakers. Works for me. Also got decent results with Nordost Pulsar points and GS DH cones, which are considerably cheaper.
Aurios under the speakers! I like to use a set of 4, not 3, under each for stability with speakers. You will need some type of boards (mdf), concrete, marble, or tile under the aurios, between them and the carpet, to maintain a hard and level surfaces. The aurios will tighten the bass bloom (or "boominess", as I prefer to call it) and will also improve staging, imaging, and PRAT!
Thanks, Fp.

I've always had trouble getting my head around bearing devices beneath speakers. I understand how they could isolate the cabinet from the floor and reduce boominess. Shouldn't they also free the cabinet to move backward whenever the cones want to move forward, thus rounding off transients? Whatever happened to Newton's 3rd Law of Motion?

Please understand, I'm not doubting what you've heard. I'm just trying to understand it.

Perhaps the answer lies in Newton's 2nd Law of Motion: the forward-moving mass (a few ounces of cones + air) is so much less than the backward-moving mass (65 pounds of speaker) that the backward acceleration is negligible. If you fire a bullet through a sheet of paper the bullet is no doubt decelerated, but you'd have a tough time measuring it. Have I answered my own question?

If Aurios are good, would Stillpoints be better? Not only do they add isolation in the vertical plane, they're half the price! Anybody?
heavy solid rock or concrete slabs are the best idea, over spikes or pads... the speaker spiked to the 75 lb to 200 lb mass of rock or concrete... works for me in my apt. (I use 2' diameter 3" thick 100lb slabs of black painted concrete with three tiptoes into the carpet, under my speakers... keeps the bass out of my downstairs neighbor's apt.)
I second the big hunk o' rock idea. Even soneting that's 20lbs should help. I would try spikes or cones under a paver slab then compare the speakers on top with spikes and some isolation. I would recomend something other than sorbothane. My experience with wood floors (no carpet) was that bass energy was going directly downward to the floor and then acting like a drum as you describe. So I only worried about verticaly transmited vibrations, and used a platform which I isolated then spiked the speakers into the platform. For isolation I used:


I bought mine cheap from a supply store that sells parts for heating and cooling contractors. I guess they are commonly used under compressors. They are firm enough that you speaker will not move (clean attack), but they stop most vibration from getting to the floor. With a paver stone the absorb the rest you should be set.

The slabs are a good idea, as are Symposium or Audio Resolution or other "draining" shelves. Actually, the shelves over granite slabs may be an awesome combo !

I have granite blocks wqith shelves, for my VMPS monitors, and they do a great job.
Sistrum speaker platforms.
Are you sure its not your amp or other component IYS?
Hi, I used Vermont marble blocks, front & rear, with iso-blocks underneath to isolate from the hardwood floor. I then installed 1/4-20 inserts on my floorstander speakers and used Soler Points. Excellent results and sweet looking too. Regards, Robin
I second the Aurios recommendation, but you need the Pro version under speakers.
Holy wow and flutter! Thanks for all the ideas everybody.

Seems like there's a concensus to spike or float the N803's above lots of mass, possibly with an absorbing layer beneath that. Maybe I can use those Sorbothane hemispheres after all, if they're not touching the speakers maybe they won't absorb transients and microdynamics. Seems a shame to waste the 10 x $2.25 they cost me!

Twl - I checked out your system page. Most of us can only imagine how much fun, and work, you've had assembling such a unique rig. Hats off to a real pioneer. I know you love the Sistrum stands, have you heard them beneath fuller range speakers than your Lowthers on a lively wood floor? Seems to me (pure speculation here) that the better they channel energy to "ground", the more that ground will shake.

Cdc - There's no question our CDP and power amp need upgrading, but our present front end really does produce *either* pretty clean bass *or* good, fast transients. The problem is getting both at the same time. We need to let our system's transients and microdynamics through, while preventing the speakers from exciting the floor.

Thanks again to all,
First thing to do is get good spikes then speaker placement will help a great deal and consider bass traps of some kind! Concrete slabs or mdf wont solve your problem but will only create another!
Just my two cents! Happy Listening

Unfortunately, there's little I can do about speaker placement. They're centered on the TV, about 10-12" farther into the room. Any position change causes audible differences in image or soundstage. We've put a lot of listening time into getting those right.

What would better spikes do? Wouldn't they just feed *more* energy into the bass drum/floor? (Admitting my ignorance.)

Bass traps. There's an idea nobody's mentioned yet! Any suggestions for good ones?

Dougdeacon, Some spikes will do a better job coupling the speaker to the floor as I find brass spikes work best for both audio componets and speakers. The tube traps or Echo Busters both work great. I use the Echo Busters and Bass Busters and improved my room. The tube traps also work good. Happy Tuning!
Great, thanks for the tips.
TWL said to use Sistrum platforms. I agree and I use Sistrum Platforms under all my audio devices. Robert will have a particular one to take care of your speaker needs. Tom
A bit of a late response but the Aurios/concrete slab system has worked great for me. I have pictures and a description of and easy way to put them togther in "my system"

UPDATE: since the previous post we've upgraded our power amp from a fifteen-year-old SAE A205 to a new c-j MF2500A.

The changes were manifold, huge and bloody (financially anyway). The point of mentioning this here is that this upgrade fixed the problem this thread addressed. The MF2500A controls the woofers while increasing slam *and* improving bass musicality in every way, quite a feat.

Heavy bass passages still vibrate the floor, more than ever, but this now has little or no effect on the music because there is no more uncontrolled bloom from the speakers. The proof is that we now clearly distinguish the primary sound of an instrument from the secondary sound of its hall decay. Importantly, this is true for even the largest and lowest-pitched instruments like bass drum, organ, tuba, etc.

We'll still try the tweaks all you helpful people suggested (because everything matters) but a special "thank you" goes to Cdc for thinking outside the box. He hit the nail on the head.