Best of both worlds.
This is what I use, the neoprene/silicon feet on a plinth which is itself spiked.
I am no mechanical engineer, but you seem to be saying that 4 tiny points of contact (the spikes) transmit the low frequency vibrational energy of the cabinet relatively unattenuated to the surface below.
If the speaker stands on the floor directly ( my wooden floor 🙂 ) the floor vibrates as you might expect. Use the spikes on their own-no plinth and it doesn't.
If I were to whack a big hammer
on the floor the whole room would shake. Whack a thin nail with the same force into the floor and it won't.
What am I not understanding ?
This is what I use, the neoprene/silicon feet on a plinth which is itself spiked.
I am no mechanical engineer, but you seem to be saying that 4 tiny points of contact (the spikes) transmit the low frequency vibrational energy of the cabinet relatively unattenuated to the surface below.
If the speaker stands on the floor directly ( my wooden floor 🙂 ) the floor vibrates as you might expect. Use the spikes on their own-no plinth and it doesn't.
If I were to whack a big hammer
on the floor the whole room would shake. Whack a thin nail with the same force into the floor and it won't. What am I not understanding ?
Attachments
If I were to whack a big hammer on the floor the whole room would shake. Whack a thin nail with the same force into the floor and it won't.
I'm not sure this is correct. If the nail does not penetrate the floor, the force transmited would be the same, and the effect in the room would be the same.
The situation is not the same if the nail is able to penetrate the floor, but you wouldn't want that with speakers.
I'm not sure this is correct. If the nail does not penetrate the floor, the force transmited would be the same, and the effect in the room would be the same.
The situation is not the same if the nail is able to penetrate the floor, but you wouldn't want that with speakers.
This brings us back to the argument that the spike does in fact alter the nature of the coupling, at least on an anisotropic flooring material. Less dramatic than a nail penetrating several millimeters of wood, but involving a far more dynamic, and different, mechanical interaction at a the spike point versus a much broader surface.
Seems like there could be different arguments here. I'm not knowledgeable enough on mechanics to add much more really. I can see what your saying over my hammer example. If all that force hits a point contact and that contact doesn't penetrate the floor then all the force has been transmitted to the floor.
Perhaps the key is in the nature of the wood in my case. The spikes do penetrate quite deeply 3 or 4mm I would guess, so the energy dispersal must be "modified" in some way.
Perhaps the key is in the nature of the wood in my case. The spikes do penetrate quite deeply 3 or 4mm I would guess, so the energy dispersal must be "modified" in some way.
If a spike has the shape of a conical pyramid, it attenuates the energy entering the large end towards the small edge by a ratio equal to the ratio of the surfaces of the two edges. Isn't it so?
That's why spikes of that sort are usually used under the Turntables, this time in their "upright" orientation. Under the speakers they should be used "upside-down" to the same effect.
And best results should be obtained if the spike end of the spikes rests on a metal plate rather than on the wooden floor or carpet, as doing so increases the surface of contact between the spike and the floor/carpet.
Isn't that correct?
That's why spikes of that sort are usually used under the Turntables, this time in their "upright" orientation. Under the speakers they should be used "upside-down" to the same effect.
And best results should be obtained if the spike end of the spikes rests on a metal plate rather than on the wooden floor or carpet, as doing so increases the surface of contact between the spike and the floor/carpet.
Isn't that correct?
Concrete floors are high Q resonant too, there is not much point in coupling energy to them.
Speaker walls resonate in the middle, not in the corners, so there is very little energy to transfer in the places where the feet or spikes are usually placed.
Long life to felt and rubber pads 😀
Speaker walls resonate in the middle, not in the corners, so there is very little energy to transfer in the places where the feet or spikes are usually placed.
Long life to felt and rubber pads 😀
Eva said:
Thanks Eva,
I agree. When you place spikes in low resonant locations you have reduced the potential to excite the substrate dramatically. 4 little points cannot do what a vibrating diaphragm can. I think spikes decouple acoustically and have the ability to anchor mechanically.
IMHO an isolation pad under a speaker has a far better opportunity to transfer energy to the floor than some properly placed spikes. If the whole bottom panel is in contact through an isolator, it's still connected. The isolation pad also allows for the speaker to "float". I can't see that being a good thing.
Just my thoughts.
If I put spikes on the bottom of my shoes would it decouple the energy of my stride from the floor.
Or would it focus all of the energy from my stride into a very small area.
Aren't most speakers designed to operate optimally in half space???
If anything the spikes may reduce the effectiveness of the Boundary coupling a tiny bit.
What if we Just bolt and glue the speakers to the surface, yahh Super coupling!!
Awesome!!!
Or would it focus all of the energy from my stride into a very small area.
Aren't most speakers designed to operate optimally in half space???
If anything the spikes may reduce the effectiveness of the Boundary coupling a tiny bit.
What if we Just bolt and glue the speakers to the surface, yahh Super coupling!!
Awesome!!!
It sounds to me like there is a trade off going on... One cannot simply say that they couple or decouple...(it sounds like) it all depends on where you place the spikes and the surface you are placing the cabinet with the spikes on... I have always thought (though it looks like I was incomplete in my thoughts) that spikes helped with a solid footing, more-so on hard surfaces such as concrete, which would then help reduce cabinet resonance because the resonances would pass into the concrete stand, thus reducing cabinet coloration...
So this leads me to wonder then, would it be best to superglue large, thick pieces of lead on the bottom of your cabinet and then set that on your stands or flooring? Would that couple mechanically and decouple acoustically best? food for thought i guess
So this leads me to wonder then, would it be best to superglue large, thick pieces of lead on the bottom of your cabinet and then set that on your stands or flooring? Would that couple mechanically and decouple acoustically best? food for thought i guess
Well... what I was taught many decades ago was that the spike acts as a sort of diode. That's why it's a spike.
The energy is allowed to drain away, but not come back. One can easily image how that might be a good thing for speaker cabinets or turntables.
Does it really work? I do not know.
The energy is allowed to drain away, but not come back. One can easily image how that might be a good thing for speaker cabinets or turntables.
Does it really work? I do not know.
My post was a little of a joke, but most of the spikes are adjustable, so for that you can balance the speakers weight and make it a little more stable. I think thats about as far as the usefulness of the spikes go.
Its not going to stop the walls of the speaker box from moving, cabinet coloration comes from the cabinet and you can't decouple a cabinet from itself.
Concrete is not a good absorber of energy I'm pretty sure very little if any energy is going to pass into the concrete, probably 99% will be effectively reflected. If you want an absorber put several layers compressed fiberglass board on the floor.
You probably wont like the sound.
Its not going to stop the walls of the speaker box from moving, cabinet coloration comes from the cabinet and you can't decouple a cabinet from itself.
Concrete is not a good absorber of energy I'm pretty sure very little if any energy is going to pass into the concrete, probably 99% will be effectively reflected. If you want an absorber put several layers compressed fiberglass board on the floor.
You probably wont like the sound.
to spike or not to spike
Hi,
If my memory is not failing me completely, one of the reasons for decouling speakers from whatever they were standing upon was to limit vibrations getting into them from the external environment such as cities, where most people live. Well, cities are quite vibrational.
The other important reason for using spikes and whatever was to decouple the rest of equipment from vibrations - mainly turntables. Speakers vibrating the floor also vibrate the turntable with known consequences. The main problem here is taht most of the materials including spikes do not decouple low frequencies.
For a very long time, well before spikes were invented, I have been using piles of old papers and phone books as base speaker stands. It does not look Versaille but works fine in most cases. One only has to keep ones wife away from trying to improve on that solution. In my next step, one day, I'll try to add spikes between paper and boxes. Has anyone tried that?
cheers,
Hi,
If my memory is not failing me completely, one of the reasons for decouling speakers from whatever they were standing upon was to limit vibrations getting into them from the external environment such as cities, where most people live. Well, cities are quite vibrational.
The other important reason for using spikes and whatever was to decouple the rest of equipment from vibrations - mainly turntables. Speakers vibrating the floor also vibrate the turntable with known consequences. The main problem here is taht most of the materials including spikes do not decouple low frequencies.
For a very long time, well before spikes were invented, I have been using piles of old papers and phone books as base speaker stands. It does not look Versaille but works fine in most cases. One only has to keep ones wife away from trying to improve on that solution. In my next step, one day, I'll try to add spikes between paper and boxes. Has anyone tried that?
cheers,
I have read this in audio circles for decades, but I don't buy it.panomaniac said:
If this were true then surely there'd be many other uses for such a device outside of audio, but I have yet to see it or to be shown an engineering paper on it from another field of vibration or acoustics.
Spikes are useful for stopping rocking on thisck carpet or similar I feel, but that's about all. Maybe enabling levelling for uneven surfaces.
I'm also pretty sure the diode analogy is not correct.
if the energy can be transmited via the spike, it can be transmited both ways, or else, there would be deformations.
Remember that vibrations is mostly like alternative current. It goes back and forth. So the concept of "the enegy goes from the speaker to the floor and do not come back" is not exactly true I believe.
My point is that IF the couling is rigid, the shape of the spike does not really matter, either it is a cone, a rod, a cube, whatever.
If the couplig is compliant, then it's another story. And i'm not sure that a mechanical link can be rigid one way and compliant the other way without deformations.
Is this correct? Interresting thread anyway.
F
if the energy can be transmited via the spike, it can be transmited both ways, or else, there would be deformations.
Remember that vibrations is mostly like alternative current. It goes back and forth. So the concept of "the enegy goes from the speaker to the floor and do not come back" is not exactly true I believe.
My point is that IF the couling is rigid, the shape of the spike does not really matter, either it is a cone, a rod, a cube, whatever.
If the couplig is compliant, then it's another story. And i'm not sure that a mechanical link can be rigid one way and compliant the other way without deformations.
Is this correct? Interresting thread anyway.
F
Hi, ( sorry for my english)
Spikes act like as springs. Very rigid springs.
The combined effect of Mass ( speaker) x springs = Resonant Frequency normally located in the 1-3 Khz.
This is bad because the system work in elastic reaction. The system is coupled below the FR and decoupled above Fr.
The woofer shake your floor and viceversa.
Diodes do not exsist in mechanic .
If you want seryously decoupling all the frequencies 20-20000Hz
you must employ a subsonic FR ie employ a very soft souspension,
ideally below 5Hz with the minimal damping (important).
In this case the system works in inertial reaction.
The souspension filter the armonic spectra of the reaction that the floor act to the speakers movements. This is good because you minimize the exchange forces (vibrations) and maximise the immobility in the audio band.
Yes the speaker float but it is near immoble in the audio band.
Best method to obtain this are air spring or use long elastics from the ceiling ( bad WAF )
You can solve all your problem of vibrations , as like every Lab in the worlds do : air spring or elastic cables tuned subsonically.
see this article
http://www.stereophile.com/reference/52/index.html
or search " damped armonic oscillator "- principle
hope this can help
cheers,
Paolo
Spikes act like as springs. Very rigid springs.
The combined effect of Mass ( speaker) x springs = Resonant Frequency normally located in the 1-3 Khz.
This is bad because the system work in elastic reaction. The system is coupled below the FR and decoupled above Fr.
The woofer shake your floor and viceversa.
Diodes do not exsist in mechanic .
If you want seryously decoupling all the frequencies 20-20000Hz
you must employ a subsonic FR ie employ a very soft souspension,
ideally below 5Hz with the minimal damping (important).
In this case the system works in inertial reaction.
The souspension filter the armonic spectra of the reaction that the floor act to the speakers movements. This is good because you minimize the exchange forces (vibrations) and maximise the immobility in the audio band.
Yes the speaker float but it is near immoble in the audio band.
Best method to obtain this are air spring or use long elastics from the ceiling ( bad WAF )
You can solve all your problem of vibrations , as like every Lab in the worlds do : air spring or elastic cables tuned subsonically.
see this article
http://www.stereophile.com/reference/52/index.html
or search " damped armonic oscillator "- principle
hope this can help
cheers,
Paolo
Your statement is true but only about power transmission between two materials of different impedance; in fact one is able to create an (almost) mechanical diode by acting on the geometry (propagation axis) and impedances (inverted direction of the elastical molecular displacement when the wave travels from low into high impedance material favours the transmission).inertial said:
😉
Hi, sorry for my english...inertial said:
If the incidental wave is an overpressure (it's almost allways the case in our acoustical vibrations), and if Za (impedance of the material in which the incident wave travels) is poor vs Zb (material onto the wave rebounces_reflexion) then this gives an overpressure of the reflexed wave (no change of this geatness vs the incidental wave), but a reversed direction of the displacement of molecules compared to the direction of the incidental wave. Thus the combined waves (incidental+reflexed) present the same direction of their molecular displacements; remember that the molecular displacement IS the physical reality of a vibration.
This phenomenon acts like a boost and helps the incidental wave to better penetrate the other material.
Inversed propagation (in my exemple Zb to Za) will increase the reflected power. Result: a diode!
I'm testing 2 POC subs at the moment - a couple of XLS10s per side. Just from experiments and observation, thick felt blocks under the subs do mean a lot less energy is transmitted to the floor. The bass sounds cleaner but quieter. With no felt or with spikes (which stick right into the floor because the subs are heavy) the subs actually excite room nodes in other rooms of the house, presumably because there is a lot of energy being transmitted through the fabric of the house.
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