[Mountain-ear]

I have been trying to improve the sound of my system (AVA electronics and Salk "Heil Heavens"), and I've come to the conclusion that I have a problem with room resonance.  The system is set up in a finished attic (aka a "bonus room").  The floor is not particularly stiff, and the carpet is really basic.  But now that the kids are out of the house, it's my turn to get the play room, and I intend to use it.

At low volumes, I have no problems.  At higher volumes, the floor seems to resonate and you can hear the bass everywhere in the house.  I was thinking that I might need to find a way to isolate or decouple the speakers from the floor to reduce the transmission of vibrations.  Some people love this idea.  Others think it is a bunch of baloney.

Possible solutions on the low end include several products from Herbie's Audio Lab.  They look promising to me, are reasonably priced, and have a money back guarantee.  On the other end, I've seen some outrageously expensive contraptions for spring loading and magnetic levitation that might cost more than the speakers themselves.  I've also seen all kinds of home remedies, including concrete slabs from the local Home Depot (with or without some supplemental dampening layer), partially inflated tire inner tubes, marbles, and tennis balls cut in half.

I know I'm not the only one with this kind of problem, so I'm hoping to learn from your experience what works and what doesn't.  What's the best way to deal with an overly active floor?  (And replacing the subfloor would exceed the limits of my otherwise very tolerant wife.)  For what it's worth, I have two Soffit Traps, two Monster Bass Traps, some diffusers and several smaller acoustic panels, all from GIK Acoustics.  I can shift them around a dozen different ways, and I can't measure (or hear) any meaningful difference using REW with a calibrated mic or a handheld Phonic PAA2.  That also makes me think that I haven't gotten to the root of the problem which is why I'm now focusing on the floor and decoupling. 

Thanks in advance.  Looking forward to your suggestions.

Steve

[catastrofe]

Steve,

I've found that in my second floor listening room, decoupling from the floor yields better sounds.  I experienced this with my SoundScape 10s, and with my Sanders 10C.  Either remove the spikes completely, or place gliders of some type under the points.  I use Herbie's Giant Decoupling Gliders.

Hope this helps. . .

[Atlplasma]

The rental I'm in at the moment has three rather creaky stories. My SongTowers and other equipment are on the second floor. I have the speakers on Herbie decoupling gliders (titanium) and the rack on decoupling gliders (stainless). I recently put my sub back into the setup and it was sounding quite bosomy. So I added in four Herbie Big Fat Dots, and the bass is now much more controlled.

I have no regrets about these purchases. YMMV of course.

[Big Red Machine]

I like the decoupling idea and for handymen like me, I might engineer me some sandboxes to try and isolate the speaker from the floor resonance.  MOre work than Herbies, but then, I like challenging projects and the opportunity to "build" something.

[AB]

My last audio room was over a garage and the floor would resonate too. I tried Auralex Subdudes and, after a bunch of trail and error, built my own decoupler stands from high density closed cell foam. The difference these made was huge.

[SteveRB]

...I'm hoping to learn from your experience what works and what doesn't.  What's the best way to deal with an overly active floor?  (And replacing the subfloor would exceed the limits of my otherwise very tolerant wife.)

I had a condo in a three story, wood frame walk up. I did a floor to ceiling reno, which included adding to the sub floor (not replacing it). The results for the hifi were incredible. The added stiffness was both felt and heard; better everything.

Just brainstorming here: you could empty the room, roll up the carpet and underlay, glue and screw a layer of 3/4" sheeting to the existing subfloor, and put everything back in a weekend. After your were done, simple spikes under your speakers would then couple them to the floor sub-floor and your over all system would be much improved.

...or you can just tell me to go away...

[Mountain-ear]

Lots of good feedback.  The sandbox idea is interesting, but Herbie's is looking better all the time with the success others have had with it. 

I agree that stiffening the floor would be a great solution, but the room runs the length of the house (20' x 40') with three dormers so that's about 30 sheets of 4x8 3/4" plywood.  I don't know what would hurt more -- my back or my pocketbook.

Steve

[ratso]

although they're made for subs, aurelex's subdude would work too i would think.  **edit woops forgot they do make one for speakers, the aurelex gramma

and someone above beat me to it anyways. 

[owlsalum1]

I faced a similar problem a few years ago living in the rented 2nd floor of a house. Ironically, for a different reason altogether (as in violating the terms of my lease!) I didn't have the option of subfloor reinforcement either. You mentioned you've moved your traps, but have you experimented with speaker position before deciding to spend money trying to deal with the problem? My ($0) first recommendation is to break up the standing modes possibly caused by regular spacing of your speakers relative to your wall boundaries. You'll find a handful of excellent articles on-line with rule- of- thumb spacing ideas for suppressing room standing modes. That's exactly what I did. With some patience and after doing my homework reading up on the physics of the room boom phenomenon I discovered  ( in my environment of course ) traps were overkill. Traps have limitations that can't be overcome - you've got to do your best to break up speaker/room boundary standing wave reinforcement first.

I've also tried sandboxes to no avail. Sand is an excellent mid/ high frequency damping material  (super for source components) but provides no low frequency suppression of significance in my experience. Just too dense. But if the no dollar recommendations you're getting don't work, hey give sandboxes a shot. Cheap and easy to make from materials you may already have laying around the house. Let us know how it goes! I for one am interested in the solution you settle on.

[Mountain-ear]

I had a business meeting in Detroit today, and I had enough time for a side trip to Pontiac to see the Salk Sound mother ship. Jim and Mary were most gracious, and I got a chance to see the magic being made. While I was there, I suggested that Jim might think about a second plinth offering built for isolation rather than coupling. He said he would think about it.

In the meantime, I will continue to play with speaker placement. I ordered some sliders from Herbie's that should make it easier to move the speakers while helping with the decoupling. I'm intrigued by the idea of asymmetrical placement as a way to counteract some room mode problems. I will confess to being obsessive about symmetry, so maybe I'm creating part of the problem.

Thanks again for the great feedback.

[Mountain-ear]

Time for an update.  Got the sliders from Herbie's.  They helped a little, but the floor was still too resonant.  So, I located the floor joists and determined that my speakers were each straddling a joist and there was no way to position them so that all four feet were supported at the same time.

Looking for a cheap enhancement, I went to my local home improvement store and got two pieces of 18" x 18" travertine (less than $3/tile) and glued them to a 3/4" base of MDF that I had laying around.  At that size, I could fully cover two joists, and the travertine added both mass and rigidity. 

In total, the new bases added about an inch to the height of the speakers.  The gliders added another quarter inch or so.  Everything shifted around a little based on the spacing of the joists, but man, what a difference.  For example, I had a serious spike at 40Hz (up about 8 db before the changes) that I cut in half.  Perhaps as importantly, the imaging of the speakers improved noticeably.  I'm not going to speculate on what caused that to happen because there were too many changes at one time (placement in the room, additional height from bases, gliders, reduced floor vibrations, etc.), but I feel like I got a new set of speakers.  Best $6 tweak I ever did! 

I might make prettier bases some day, but for now, I'll just enjoy the improved sound.  Thanks to all for your suggestions!

[mick wolfe]

Steve,

I've found that in my second floor listening room, decoupling from the floor yields better sounds.  I experienced this with my SoundScape 10s, and with my Sanders 10C.  Either remove the spikes completely, or place gliders of some type under the points.  I use Herbie's Giant Decoupling Gliders.

Hope this helps. . .

That's been my exact experience dealing with "suspended" wood floors and spikes. It was a few years back when I lived in Illinois, but if memory serves me correct, it turned my entire listening room into a speaker cabinet. The speakers I had at that time came with casters. ( JSE Infinite Slopes) Within a couple of days, the casters were back in place and decent sound returned. Now that I'm in Arizona where concrete floors are common, spiking yields excellent results.

[rollo]

   How about reinforcing the floor if possible. We used Lolly columns or screw jacks to raise the floor as required to tighten it up. If this is not possible castors. If you spike to floor same issue. Decoupling can work however if floor is really loose they will be semi affective.


charles

[DaveC113]

Another option, I got the sub one and am blown away by how good it is.

http://www.sweetwater.com/store/detail/ISOL8R200

[Austin08]

Another option, I got the sub one and am blown away by how good it is.

http://www.sweetwater.com/store/detail/ISOL8R200

Cool!!! I saw the dimension is 4" rise. Is that total height? Can you measure exactly the heigh front and back. I may use these as my center channel speaker stand. Thanks

[Big Red Machine]

There's always one of these:

[DaveC113]

Cool!!! I saw the dimension is 4" rise. Is that total height? Can you measure exactly the heigh front and back. I may use these as my center channel speaker stand. Thanks

It's actually 5" total, no tilt on the subwoofer model I have.

[Austin08]

It's actually 5" total, no tilt on the subwoofer model I have.

Thanks Dave. A bit highet than I expected.

[Martyn]

I had some 30 mm granite left over after renovating our kitchen, so I had my supplier cut me some rectangles slightly larger than my speakers (and polish the edges). I then glued a set of spikes to the undersides with epoxy. Take a look at the photograph:




I then used four simple polyurethane feet from Lee Valley (I think I used 00S20.21 here: http://www.leevalley.com/en/hardware/page.aspx?p=62154&cat=3,40993,41285) between the speaker and the granite.

So the spikes couple the granite to the suspended floor, but only through four points, and get the whole arrangement clear of the carpet. The polyurethane feet are soft enough to decouple the speaker cabinet from the granite. Seems to work quite well.

The most expensive part was getting the edges of the granite polished, but I had a stack of them done for use not only with speakers, but also as cheeseboards and pizza stones! I can't stand seeing things go to waste!

[JLM]

Solid to solid, float to float.  This is classic problem brought about by "too much" deep bass that imparts lots of energy into the surroundings.

No point in trying to anchor (couple) to a relatively soft/resonant floor, especially over a crawl space (or even a full floor below).  The floor becomes a huge dipole, the crawl space/floor below a huge resonator.  A serious solution for the floor would be to double up the studs (carpenters call is sistering), add plywood sub flooring/masonry flooring, and plywood to the underside of the floor joists.  That would significantly stiffen up the floor and add mass.  But in any case you're picking up some of the "sonic characteristics" of the additional mass (think of a speaker strapped to the end of a diving board).

Dave's suggestion obviously comes from the professionals.  We may not agree with their taste in gear, but we should respect their experience and knowledge.  Isolation removes more unknowns (resonant frequency of the studio table/floor/space below) than coupling to unknown floor/space conditions.  Proper isolation has to be tuned to the speaker mass and the frequencies it covers.  In the case of a wide frequency speaker I'd aim low as the bass would have the bulk of the offending energy.

My experience is that sound travels down a structure easier than up.  In college I was returning from the basement laundry Sunday afternoon and heard a stereo playing.  It was mine from the 4th (top) floor of the 300 resident fully masonry dorm, that my "friends" were playing with.