2. tech-talk
  3. 1184935436

To spike or not to spike, that, is the question.


….my rack, that is.

I know this is covered repeatedly yet I’ve seen nothing pertinent to it in hollow floor applications. My current boat anchor, er, Sound Anchor rack, poses me an issue in this area of resonance control… or just something to do.

HOWEVER there seems a decision needs be made on either coupling, or de-coupling presently. Given it’s size and weight, I’d sure not want to be dancing it onto and or off of different footer gizmos over and over again.

I would like to know what experiences anyone has in this regard... and with what manufacturers' spikes or what-not.

My floor is hollow... carpet & pad over 5/8 flooring, on 16 OC 2x10 joists.

I'm thinking to add a piece, or two, of plywood (1/2 - 1 inch) underneath the rack and on top of the carpeting & pad, right off. Thus adding foundation & support.... as the weight will be near +/- 425 lbs with the components aboard.

How thick to go doesn’t seem as much the issue as does perhaps, the overall width and length though… as increasing the area coverd should help spred the disbursement of the weight atop it.

Rack exterior dims are roughly, 24 x 18. I was thinking to add two - three inches all around and use no less than ½ inch 5 layer ply.

So if the above doesn’t seem a bad idea, the couple or de-couple item is all that is undecided.

Thanks much, as I do sincerely appreciate the input.
blindjim
jaybo
4,478 posts
 
never spike
blindjim OP
3,092 posts
 
Do tell.
mikelavigne
2,199 posts
 
you have a few issues going on here.

a suspended wood floor as you describe has two main challenges; it will transfer footfalls to your gear and also transfer the acoustic feedback from your speakers to the rack.

with a suspended wood floor the best solution is to brace the floor below under the speakers and rack if possible. if it is a crawl space or basement then ideally you would install some beams onto concrete floor or pads. if this is possible there are specific methods to use.

if it is not possible to brace the floor then the next best approach would be to dampen the floor under the rack and speakers to reduce the level of energy which gets transfered from the speakers to the floor and the floor to the rack. this can be done by 'mass loading' the floor with a tray of sand......the sand will absorb much of the resonance from the floor. you would want to spike the 'sandbox' to the floor thru the carpet to firmly attach it to the floor.....or it will be 'squishy' and not really dampen.

then use some sort of de-coupling footer (which decouples in the verticle plane) on the platform resting on the sand. there are a number of these..... still points, Apex footers....etc. this approach gives you alternate layers of mass and decoupling. the level of benefit will depend on how much floor movment you have. it will help with acoustic resonance but likley will not do much for footfalls.

an alternative to all this would be getting a Grand Prix rack system with Apex footers. it is designed to deal with suspended wood floors by using different layers of decoupling. the shelves use special sorbothane pads to dampen resonance; these pads are tuned to your specific gear. the legs of the Grand Prix rack actually are flexible and decouple; and finally the Apex footers absorb quite a bit of resonance. in addition to all this decoupling; the legs can be filled with sand or lead shot to tune the rack to the specific floor conditions.

it's not cheap but short of extemely expensive active isolation the Grand Prix is the very best rack solution for suspended wood floors.
blindjim OP
3,092 posts
 

Mikelavigne
Thanks much, I appreciate it greatly.

Getting up underneath the floor and adding cross braces from one joist to another likely won't happen. At best might be some more foundational supports to the closest placements of the spkrs & rack... maybe.

Footfalls aren't an issue. I'm alone. Neither are acoustic/air vibrations as the components reside in a closed off, and seperate room from the speaker/sub, and me when listening.

Sand box, huh? how big/deep should it be for this Sound Anchor rack which I think weighs in around 180 dry, and about 440lbs. (+/-) filled with devices & wires???

These 'sand boxes' don't subtract from the harmonics in any shape or form, do they? (dulling transients, occluding inner detail, etc)

A GP rack or any other rack for that matter, just ain't happening. Period.

Apex footers? Maybe. If they will attach to the SA racks threaded opening and don't cost a great deal.

Couple the sand box to the existing flooring, and de-couple the rack resting atop the box, from it?

Same way for speakers? They weigh in at 90lbs ea give or take a bit.

I'll assume you have done this and realized good results?

Thanks again for the help here.
More to discover