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haroon
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Wooden floor is alive, Coupling, Decoupling the speakers or.....?

Hello:

I have recently moved to new apartment and now face a strange problem. The building is very old and wooden floor is too alive. If I am walking in one corner of apartment the vibration from steps can be felt in other corner. Banging the floor with foot gives you a sense that furniture and fixture is going down. I have installed padding and carpet to calm down the footfalls.

With or without spikes (spikes hardly penetrate padding and carpet) my floor standing speakers seems to have lost all of their talents. Bass is especially blotted and extremely loose. One can feel the floor playing in harmony when playing music.

I do not worry about the carpet or floor. Please help me with some solution?

Jeff Wong
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Re: Wooden floor is alive, Coupling, Decoupling the speakers or.

This could be a tough one. You might try placing some heavy weights on top of the speakers (granite slabs?) or if you're feeling extreme and not worried about looking insane, build braces that wedge between the speakers and the ceiling. Granite slabs under the speakers might be more practical.

Jan Vigne
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Re: Wooden floor is alive, Coupling, Decoupling the speakers or.

Spikes do not really "couple" the speaker to the floor. The effect of spikes is to mass load the speaker onto a few very small points of contact with the surface. This gives the equivalent of addding mass to the enclosure and "fixing" the drivers along a solid, immovable plane from which to operate. Decoupling the speaker enclosure from its support surface will give the opposite effect and wouldn't be my first choice in virtually any situation. The spikes need to touch the floor through the carpet. If they don't, then you're still decoupling the speaker from any solid support by placing the cabinet on a spongy surface. No matter how you manage the decoupling, it will allow the enclosure to move slightly in response to the movement of the drivers. The result of that wobble is generally lesser performance in bass response and soundstaging.

My first suggestion would be to find a support for the speakers to rest upon that helps fix the cabinets in space. Concrete slabs would be where I would begin just due to price. Experiment with the solid slabs in order to make certain the speakers don't wobble when you push on any edge. The concrete should act as a sufficient energy sink for the speakers. After you're certain the speakers are not going to wobble you can work on the next step. I'm not clear whether bass is the only problem you have in this new apartment, but, in any case, I would work on speaker placement. If you can access the floor joists, locate the speakers as close to the joists as possible to give the speakers the most support they can find in this room. If you can get two or three corners resting on the location of a joist, you should minimize the movement of the floor. If you are unfamiliar with how to do a proper speaker set up, refer to this thread; http://forum.stereophile.com/forum/showf...=true#Post13021 I would begin with a one third placement into the room.

Get another carpet pad to further dampen the vibration of the floor. If you might be allowed by the owner, you can reinforce the floor from beneath with some concrete blocks and shims. Beyond those points, I can't think of much you can do to help the situation. You can look on the bright side in that most older homes have walls with plaster over lathing. That makes for a more solid wall than most modern apartments with aluminum studs and dry wall.

Did you not notice the situation with the floors when you were apartment hunting?

haroon
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Re: Wooden floor is alive, Coupling, Decoupling the speakers or.

Thanks Jeff and Jan (sound perfect together). Jan, I am thankful to God that I got something to live in NYC within student budget.

Jan, I understand your point about mass loading and why Jeff purposed the granite slabs. I can't do much with the floor as it's the 3rd floor and NYC landlords are very rough people.

I am aware of speaker setup techniques and have experiment with many in previous apartment. Yes! Bass is not the only problem. In fact I am not a bass fan. As I originally wrote the speakers have lost their magic. Everything is muddy and confused. Even, my wife commented that something is wrong with music.

I am not contesting what Jan wrote about micro movements in speaker cabinets as a reaction to drivers' movements. However, I am little unsure that the drivers can move a 36kg cabinet even at micro level. The speakers are heavy and it is not very easy for me to move them. But then I don't know how much force the mid and the bass drivers are exerting on the cabinets.

Have anyone heard about any study where a speaker is put onto ball bearings and tested for micro movements? Any experiment where weight of speaker was put against SPL and frequency the driver was producing?

Have anyone tried the Vibrapods on speakers? The ideal aim is to stop the speaker from moving but also to stop floor vibrations. What if I place a slab (granite, wood, concrete...) on floor and then place the speaker on slab using vibrapods? Read the third last paragraph of http://www.soundstage.com/synergize/synergize011999.htm.

Although I am not sure about the scientific evidence of driver movements vs. micro movements in cabinet, intuitively I agree with Jan about mass loading the speakers. I didn't think about concrete slabs but now I will be trying them soon.

Buddha
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Re: Wooden floor is alive, Coupling, Decoupling the speakers or.

Hi, and welcome.

I think I am about to commit Hi Fi Heresy, but here goes...

1) Consider asymmetric/random floor damping. I think this is the best way to break up room node and floor bounce.

They make different vibration damping floor mats that are used for workers to stand on who work with vibrating machinery.

Look around, I haven't done it for a while, so I'll be lazy and hand off the assignment to you.

Then, buy some in different sizes, or cut some up in different patterns and place them around the room under that carpet you lay to make for a more appealing visual.

You can even get some thin plates of other materials that are thin and use Blu-tak to couple them to the floor and end up with different materials in random places.

You can use almost any combination of flat materials, just try and use stuff that leans toward "dense feeling."

Then again, tossing in some non-dense can help to, so go nuts and play.

You can even be creative and get all sorts of different thin but dense things and try them in lively or random places on the floor.

That may not take out all the "springy-ness," but it would help break up certain symmetry based floor vibration modes that would potentially reinforce or attenuate your sound at different frequencies.

You can even make creative patterns out of "Quick Crete" and make a sort of mosaic of different tiles with different things mixed with the "Quick Crete" to make for different densities. You could put some lead shot in some tiles, sand in others, the possibilities are endless, and cheap.

2) Both couple and uncouple your speakers from the floor. I agree with you, I don't think you'd gain as much from "fixing your speaker in place" as you would from making the most advantageous use of trying to minimize your floor/speaker interaction, at this point.

I think you should invent your own "constrained layer" kind of damping and get some good spikes to place where floor meets stand.

Then, a nice, rigid stand.

Then, a compliant damping support - something to take up the speaker's vibration.

Maybe even sorbothane.

Then, another rigid piece of material.

Then, another good "coupler" to make the speaker and stand act like the spikes and the floor.

I know people will yell, "Smearing!", but what you can gain by damping the speaker's effect on the floor, and vice versa should add more detail than the "suspension" layer would take away.

3) Blasphemy of blasphemy:

Consider hanging the speakers from the floor joist of the floor above.

Yes, you'll lose those micrometers that the speaker may move, but you'll gain alot in isolating the speaker from the room.

People used to "hang" Magneplanars and I've heard it sound awesome.

4) Mount all your gear racks on the wall, taking them out of the floor-rack equation for propogating floor vibration into your source material.

I know it sounds like lots of work, but most of it is potentially very cheap to implement.

Best wishes.

Jan Vigne
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Re: Wooden floor is alive, Coupling, Decoupling the speakers or.

You seem to be confused about what is causing the floor to vibrate. Even if the speakers are quite heavy, it is not so much the cabinet vibration that is moving the floor. It is the air in the room. Just as the speaker cabinet mostly vibrates in response to the changing internal pressure caused by the driver's movement, so too will the room surfaces, the floor being the most often most problematic, respond to the changing pressure in the room created by the movement of the drivers out into the room. In other words, the floor vibrates as it reacts mostly to the changing pressure in the room enclosure. It is acting as the "external enclosure" of the drivers and reacting in a similar fashion to the speaker cabinet's response to internal pressure changes. Therefore, actually decoupling the speaker from the room means moving the speaker out of the enclosure of the room. Make sense?

The link you supplied doesn't go anywhere for me. But, I wouldn't try the Vibrapods under speakers. You will in effect be placing large rubber feet under the speaker and while the Vibrapods are a bit more sophisticated than give away feet, they are meant to act as a lossy interface. You already have that in your carpet and pad. Adding another lossy material on top of that will probably not be a good solution.

No matter how heavy your speakers are, the carpet and pad still act as a lossy interface between the floor and the speaker cabinet. That means the speaker will have micro-movement even if it is quite heavy. Spiking is meant to fix the cabinet in space by eliminating the spongy interface. You are once again looking only at what you consider the offending item and missing the larger problem. It is not so much the movement of the driver that causes the micro-movement. It is the drivers acting against the external air pressure in order to create a pressure change in the room. It's a bit of an exageration, but the drivers are pushing against the weight of the world and by comparison your relatively puny 36kG cabinets are the only thing keeping them from toppling over. Spiking to achieve mass loading increases the odds the driver will react only to the electrical voltage changes needed to make its motor assembly react.

Since you are fairly limited in your possible solutions, there may not be a best tact for completely alleviating the problem. I would still start with speaker placement. If everything in the sound quality has gone ka-flooey, you probably have room problems at many frequencies. Reflected pressure waves are most often the cause of muddy sound from the midbass on up. The answer to this problem is both speaker/listening position placement and room treatment. How does the system sound from another room?

Damp the first reflection points and that should be the first step in clearing up the sound through the midrange and upward. Further adjustments and treatments will eventually solve the muddiness issue.

Have you asked you downstairs neighbors what they hear when you play your system?

Buddha
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Re: Wooden floor is alive, Coupling, Decoupling the speakers or.

Well, now I'm curious about something.

Do people making recordings ever spike a performer's chair to the floor?

I would think that could cause alot of micro-movement, especially with the horn players.

Also, how do we get them to hold still? I bet they exhibit more micro-movement than any 37 Kg speaker sitting on the floor.

Also, are mic stands spiked to the floor?

This thread's getting me all worried about micro-movement higher up in the chain.

Also, if his room acts too much like an "external enclosure," could he experiment with opening windows and doors to create a ported external enclosure rather than an acoustic suspension external enclosure?

You'd think windows and doors could exert a huge effect in his case.

Jan Vigne
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Re: Wooden floor is alive, Coupling, Decoupling the speakers or.

I assume you're joking, but ...

You answered your own question concerning performers. Spiking the chair doesn't stop the instrument from moving. But, once again, the point has been missed. The original instrument creates the sound we are trying to reproduce. Movement of the instrument relative to a fixed space doesn't degrade the sound since it becomes part of the original sound. Movement in the reproducing instrument, does degrade the sound because it doesn't accurately reflect the original source.

Microphones are not spiked but rather are decoupled in most instances in order to accurately capture the original pressure changes without interference from external sources. You are again mistaking the pressure changes at the diaphragm of the microphone with the pressure changes caused by the reproducing equipment. External pressure changes are moving the microphone's diaphragm which converts those movements into electrical energy. Due to the relative size of the diaphragm in relation to the microphone's "enclosure", the effects of resonance on the electrical signal passed to the mic cable are typically quite minimal. Not insignificant, but minimal. What is captured at the point of transduction is the signal we are trying to reproduce. Could the signal quality be improved by rigidly fixing the diaphragm in space with a massively inert support system? Possibly, but that is an issue you will have to take up with the Stagehands Union as I suspect most roadies would object to tweaking the placement of an immovable object.

Unless the room is completely air tight and as inert and rigid as possible, as is a properly constructed AS enclosure, the room does act as a sort of vented enclosure. Windows and doors do make some difference in the "tuning frequency" of the room though usually rather slight due to the dimensions of each part of the equation. Normally doors and windows have an effect in relation to the lack of rigidity and air leaks they offer. In the case here, altering the resonant frequency of the "system" won't solve the problems related to lack a of rigidity.

Buddha
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Re: Wooden floor is alive, Coupling, Decoupling the speakers or.

Hi, Jan.

I was just goofing off. Apologies for my obtuse-ness.

I really like your posts and would not want to subvert them.

Cheers.

absolutepitch
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Re: Wooden floor is alive, Coupling, Decoupling the speakers or.

I have several floor-standing speakers. On one pair, I took the cheapest solution as a first try, before considering spikes and cones. I got eight furniture feet with integrated nails (the kind that is intended to be nailed into the bottom of chairs, tables, etc.). I turned the nail end down through the carpet and pad into the wood floor. Then I placed each under a corner of the speaker bottom. In my case the bass improved. Your situation could be a problem with the floor as others have suggested, but this is a inexpensive way to see if it helps.

My new set of speakers have casters for easy movement. I have not tried the same method, as the casters will roll off the pseudo-spikes I used. I have yet to try something else.

Brainstorm4645
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Re: Wooden floor is alive, Coupling, Decoupling the speakers or.

Place MDF all over the floor area and then lay down (concrete slabs) now then, If that doesn

xuxu
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Re: Wooden floor is alive, Coupling, Decoupling the speakers or.

instead of fighting the problem why not use the "live" floor to your advantage?

http://www.si5.com/products.php?pID=4024

CECE
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Re: Wooden floor is alive, Coupling, Decoupling the speakers or.

This idea sounds like how they built the Big Dig tunnel in Boston, just do it, we don't need no stinkin' real design work, or ENGINEERS with qualifications. Who cares if the supports and mounts can't handle the loads.

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